JP5853423B2 - Steering support apparatus and steering support method for vehicle - Google Patents

Description

  The present invention relates to a vehicle steering assistance device and a steering assistance method for providing information to assist a steering operation to a driver via a steering wheel.

2. Description of the Related Art Conventionally, there is a steering assist device that provides information to assist a steering operation to a driver via a steering wheel (steering wheel) for the purpose of positioning the host vehicle in a traveling lane. An example of such a steering assist device is described in Patent Document 1.
The steering assist device described in Patent Document 1 is a technology that outputs a target value of a motor current defined by a polygonal line function according to the magnitude of a steering angle deviation between a target steering angle and a current steering angle. This is a technique for reducing the steering operation burdened by the driver. Such a steering assist device is intended to output a sufficient propulsive force (steering assist torque) to the steering wheel when the steering wheel is controlled to reduce the burden on the driver in the steering operation.

Japanese Patent Laid-Open No. 11-78942

However, in the steering assist device described in Patent Document 1, the value of the motor current is reduced when the steering angle deviation is small. Therefore, when the current steering angle exceeds the target steering angle, the target is set. There is a concern that the convergence to the steering angle may deteriorate. When the convergence to the target steering angle deteriorates, when driving on narrow roads, S-shaped roads, crank roads, etc., it is necessary to generate a strict steering angle, or to achieve the target steering angle with quick steering Under certain circumstances, there may be a problem that it is difficult to provide reliable steering assistance.
The present invention has been made paying attention to the above-described problems, and an object of the present invention is to provide a vehicle steering support device and a steering support method capable of improving the reliability of steering support.

In order to solve the above problems, the present invention calculates a target route that the host vehicle should follow from an image of the traveling direction of the host vehicle, calculates a target steering angle from the target route, and provides a target state of the host vehicle. Then, the calculation accuracy of the state deviation degree that is the deviation degree from the current state of the host vehicle is estimated. Furthermore, when outputting the steering assist torque to the steering wheel, an attenuation command signal for attenuating the steering assist torque is calculated, and when the calculation accuracy is low, the degree of attenuation of the steering assist torque is increased compared to when the calculation accuracy is high. In this manner, an attenuation command signal is calculated.
The steering assist torque is a torque for reducing the state deviation degree. The damping command signal indicates that the steering assist torque attenuation degree is larger than the preset attenuation degree when the state deviation degree tends to decrease, and the steering assistance torque attenuation degree is preset when the state deviation degree tends to increase. It calculates so that it may become below the degree of attenuation.

  According to the present invention, the closer the current state of the host vehicle is to the target state, the stronger the damping force of the steering assist torque acts on the steering wheel. For this reason, the steering angle of the host vehicle can be quickly converged to the target steering angle, and the reliability of steering support can be improved.

It is a block diagram which shows the structure of the steering assistance apparatus of 1st embodiment. It is explanatory drawing for demonstrating the output law of the torque command value output via a torque command value calculation apparatus and a torque command attenuation circuit. It is a flowchart which shows the process which the steering assistance apparatus of 1st embodiment performs. It is a block diagram which shows the structure of the steering assistance apparatus of 2nd embodiment. It is a figure which shows schematic structure of the own vehicle provided with the steering assistance apparatus of 2nd embodiment. It is explanatory drawing for demonstrating the output law of the torque command value output via a torque command value calculation apparatus and a torque command attenuation circuit. It is a flowchart which shows the process which the steering assistance apparatus of 2nd embodiment performs. It is a block diagram which shows the structure of the steering assistance apparatus of 3rd embodiment. It is a figure which shows the relationship between an obstruction and the own vehicle. It is explanatory drawing for demonstrating the output law of the torque command value output via a torque command value calculation apparatus and a torque command attenuation circuit. It is a flowchart which shows the process which the steering assistance apparatus of 3rd embodiment performs. It is a block diagram which shows the structure of the steering assistance apparatus of 4th embodiment. It is explanatory drawing for demonstrating the output law of the torque command value output via a torque command attenuation circuit. It is a flowchart which shows the process which the steering assistance apparatus of 4th embodiment performs.

Embodiments of the present invention will be described below with reference to the drawings. In the following description, four embodiments (first to fourth embodiments) are described as embodiments relating to the present invention.
(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

(Constitution)
FIG. 1 is a block diagram showing the configuration of the steering assist device 1 of the present embodiment.
As shown in FIG. 1, the steering assist device 1 of the present embodiment includes a target steering angle calculation device 2, a steering angle sensor 4, a steering angle deviation calculation circuit 6, a steering angular velocity sensor 8, and a torque command value calculation. A device 10, a torque command attenuation circuit 12, and an EPS 14 are provided.
The target steering angle calculation device 2 includes an imaging circuit 16, an image processing circuit 18, a target route calculation circuit 20, and a target steering angle calculation circuit 22.

The imaging circuit 16 is formed with a CCD camera or the like, for example, and acquires an environment around the host vehicle (for example, the front of the host vehicle in the front-rear direction). Then, the imaging circuit 16 outputs an information signal including the acquired image to the image processing circuit 18.
The image processing circuit 18 performs edge detection or the like on the image acquired by the imaging circuit 16 based on the information signal input from the imaging circuit 16, and further recognizes the object, so that the host vehicle travels on the road. Detect possible areas. Then, the image processing circuit 18 outputs an information signal including the detected area to the target route calculation circuit 20.

Here, the object to be recognized is specifically a white line on the road indicating the boundary of the traveling lane, a wall, an obstacle existing on the road, another vehicle, a pedestrian, or the like. And the area | region where these objects do not exist becomes an area | region where the own vehicle can drive | work on a road.
The target route calculation circuit 20 calculates a target route that the host vehicle should follow in the area detected by the image processing circuit 18 based on the information signal input from the image processing circuit 18, and an information signal including the calculated target route. Is output to the target steering angle calculation circuit 22.

  Specifically, when calculating the target route, first, the area that can be traveled by the image processing circuit 18 and the other areas that are present on the left and right sides of the host vehicle from the area that the host vehicle can travel The boundary (the left boundary in the vehicle width direction and the right boundary in the vehicle width direction) is detected. Then, a plurality of straight midpoints connecting the boundary on the left side in the vehicle width direction and the boundary on the right side in the vehicle width direction in a region where the vehicle can travel are obtained, and a set of these midpoints is calculated as a target route.

The target steering angle calculation circuit 22 is a target that is a target rotation angle (steering operation amount) of the steering wheel from the target route calculated by the target route calculation circuit 20 based on the information signal input from the target route calculation circuit 20. Calculate the steering angle. Then, the target steering angle calculation circuit 22 outputs an information signal including the calculated target steering angle to the steering angle deviation calculation circuit 6.
Therefore, in the present embodiment, the target state of the host vehicle is set as a target steering angle that is a target rotation angle of the steering wheel. In the following description, the target steering angle may be described as “target steering angle θ ^* ”.

When calculating the target steering angle θ ^* , specifically, first, a point on the target route that is predicted to pass after t seconds from the current position of the host vehicle is set as a target point on the travel route of the host vehicle. To do. Then, a steering angle necessary to reach the set target point is calculated from the current position of the host vehicle on the road and the rotation angle of the steering wheel at the current position, and the calculated steering angle is calculated as the target steering angle θ ^*. And

Here, in the present embodiment, a vehicle motion model is stored in advance in the target steering angle calculation circuit 22, and this vehicle motion model is used for calculating the target steering angle θ ^* . For this reason, it is possible to calculate the target steering angle θ ^* more accurately.
The vehicle motion model is, for example, a model indicating vehicle motion (yaw rate or the like) generated according to the steering angle and speed when the host vehicle is traveling, and is a parameter specific to the vehicle.

Thus, the target steering angle calculating unit 2 calculates a target steering angle theta ^*, the information signal including a target steering angle theta ^* that this calculation is output to the steering angle deviation calculation circuit 6. As a result, the target steering angle calculation device 2 provides the steering angle deviation calculation circuit 6 with an information signal including the target steering angle θ ^* which is the target state of the host vehicle equipped with the steering assist device 1.
The steering angle sensor 4 is provided, for example, in a steering column that rotatably supports the steering wheel, and detects a current steering angle that is a current rotation angle (steering operation amount) of the steering wheel by the driver. Then, an information signal including the detected current steering angle of the steering wheel is output to the steering angle deviation calculation circuit 6.

Therefore, in the present embodiment, the current state that is the current state of the host vehicle is set as the current steering angle that is the current rotation angle of the steering wheel. In the following description, the current steering angle may be described as “current steering angle θ”.
In recent years, a vehicle often has a sensor that can detect a steering angle of a steering wheel as a standard. For this reason, in this embodiment, the case where the sensor which can detect the steering angle of the steering wheel existing in the vehicle is used as the steering angle sensor 4 will be described.

The steering angle deviation calculation circuit 6 detects the target steering angle θ ^* calculated by the target steering angle calculation device 2 and the steering angle sensor 4 based on the information signals input from the target steering angle calculation device 2 and the steering angle sensor 4. A steering angle deviation which is a difference from the current steering angle θ is calculated.
Therefore, in the present embodiment, the state deviation degree, which is the degree of deviation between the target state and the current state, is set as a steering angle deviation which is a difference between the target steering angle θ ^* and the current steering angle θ. In the following description, the steering angle deviation may be described as “steering angle deviation δθ”.

Here, when calculating the steering angle deviation δθ, the target steering angle θ ^* is subtracted from the current steering angle θ. Therefore, the steering angle deviation δθ is calculated by the following equation (1).
δθ = θ−θ ^* (1)
Further, the steering angle deviation calculation circuit 6 outputs an information signal including the calculated steering angle deviation δθ to the torque command value calculation device 10 and the torque command attenuation circuit 12.

Similar to the steering angle sensor 4, the steering angular velocity sensor 8 is provided, for example, in a steering column that rotatably supports the steering wheel, and is a steering angular velocity at the time of the current steering of the steering wheel by the driver of the host vehicle. Detect angular velocity. Then, an information signal including the detected steering angular velocity is output to the torque command attenuation circuit 12. In the following description, the steering angular velocity may be described as “steering angular velocity θ ′ ₁ ”.

In recent years, a vehicle often has a sensor that can detect a steering angular velocity of a steering wheel as a standard. For this reason, in this embodiment, the case where the sensor which can detect the steering angular velocity of the steering wheel existing in the vehicle is used as the steering angular velocity sensor 8 will be described.
The torque command value calculation device 10 is a command value of a steering assist torque for reducing the steering angle deviation δθ calculated by the steering angle deviation calculation circuit 6 based on the information signal input from the steering angle deviation calculation circuit 6. A torque command signal is calculated. Then, the torque command value calculation device 10 generates the calculated torque command signal and outputs it to the torque command attenuation circuit 12. In the following description, the torque command signal may be described as “torque command value _To1 ”.

In the present embodiment, as an example, a case will be described in which the torque command value _To1 is calculated using the map shown in FIG. 2A and the following equation (2). FIG. 2 is an explanatory diagram for explaining an output rule of the torque command value _To1 output via the torque command value calculation device 10 and the torque command attenuation circuit 12.
T _o1 = K ₁ × δθ = K ₁ × (θ−θ ^* ) (2)
In the above equation (2), “K ₁ ” is a coefficient corresponding to the convergence speed to the target steering angle stored in the target steering angle calculation circuit 22. This coefficient is set as a fixed constant or a variable corresponding to the vehicle speed or the like. Further, as shown in the above equation (2), the torque command value _To1 is a value proportional to the steering angle deviation δθ.

The torque command attenuation circuit 12 attenuates the torque command value _To1 calculated by the torque command value calculation device 10 based on the information signals input from the steering angle deviation calculation circuit 6, the steering angular velocity sensor 8, and the torque command value calculation device 10. The attenuation command signal to be calculated is calculated. Then, by generating a torque attenuation command value obtained by attenuating the torque command value T _o1 by the calculated attenuation command signal, and outputs it to EPS14.

Here, when calculating the attenuation command signal, the torque command attenuation circuit 12 performs branching based on the comparison described below.
Specifically, the steering angle deviation δθ calculated by the steering angle deviation calculation circuit 6 is compared with a preset steering angle deviation coefficient ξ shown in FIG. Further, the current steering angle θ and the target steering angle θ ^* are compared based on the comparison result between the steering angle deviation δθ and the steering angle deviation coefficient ξ.
The “steering angle deviation coefficient ξ” is, for example, a coefficient (damping torque coefficient C ₁ ) used when generating a torque damping command value with reference to the target steering angle θ ^* as shown in FIG. _Is a threshold value that makes the minimum value ( _{Cl 1} ) or more, and is set as a fixed constant or a variable according to the vehicle speed or the like.

Then, depending on the comparison result between the steering angle deviation δθ and the steering angle deviation coefficient ξ, or the comparison result between the current steering angle θ and the target steering angle θ ^* , one type of torque attenuation command value T ₁ among the three types. Is generated.
Torque command attenuation circuit to generate a torque attenuation command value T ₁ 12 is a command signal including a torque attenuation command value T ₁ that the generated outputs to EPS14.

Hereinafter, a comparison result between the steering angle deviation δθ and the steering angle deviation coefficient ξ, or a comparison result between the current steering angle θ and the target steering angle θ ^*, and three types of torque attenuation commands generated according to these results The relationship with the value T ₁ will be described.
As a result of comparing the steering angle deviation δθ with the steering angle deviation coefficient ξ, if the steering angle deviation δθ is greater than or equal to the steering angle deviation coefficient ξ, the torque command attenuation circuit 12 calculates the minimum attenuation torque signal T _min1 . The minimum attenuation torque signal T _min1, of the attenuation command signal to attenuate the torque command value T _o1 the torque command value calculating unit 10 is calculated, the torque command value T _o1 attenuation degree minimum of (torque command signal) Is.

Then, the torque command attenuation circuit 12, the minimum attenuation torque signal T _min1 calculated, and added to the torque command value T _o1 the torque command value calculating unit 10 is calculated, to generate a torque attenuation command value T _1. In this case, the torque attenuation command value T ₁ is a value represented by the following equation (3).
T ₁ = T _o1 + T _min1 (3)

In the present embodiment, as an example, the minimum damping torque signal T _min1 is calculated using the damping torque coefficient C ₁ (C ₁₁ ) having the value shown in FIG. 2B and the following equation (4). The case where it does is demonstrated. Further, “C ₁₁ ” shown in FIG. 2B is the minimum value of the damping torque coefficient C ₁ .
T _min1 = C _l1 × θ ' ₁ (4)
Here, the case where the steering angle deviation δθ is greater than or equal to the steering angle deviation coefficient ξ means that the current steering angle θ changes in a direction away from the target steering angle θ ^* , and the steering angle deviation δθ tends to increase. is there.

That is, the steering assist torque attenuating means 12 attenuates the torque command signal so that the degree of attenuation of the torque command signal is equal to or less than a preset degree of attenuation when the steering angle deviation δθ calculated by the steering angle deviation calculating circuit 6 is in an increasing tendency. Calculate the command signal. In the present embodiment, in a state where the steering angle deviation δθ calculated by the steering angle deviation calculation circuit 6 tends to increase, an attenuation command is set so that the degree of attenuation of the torque command signal (torque command value _To1 ) is minimized. A case where a signal (minimum damping torque signal T _min1 ) is calculated will be described.

On the other hand, as a result of comparing the steering angle deviation δθ with the steering angle deviation coefficient ξ, if the steering angle deviation δθ is less than the steering angle deviation coefficient ξ, the torque command attenuation circuit 12 is calculated by the target steering angle calculation device 2. The target steering angle θ ^* is compared with the current steering angle θ detected by the steering angle sensor 4. This comparison is performed when the current steering angle θ is changing in a direction approaching the target steering angle θ ^* , that is, when the driver is steering the vehicle toward the target.

As a result of comparing the current steering angle θ and the target steering angle θ ^* , if the current steering angle θ does not pass the target steering angle θ ^* , the torque command attenuation circuit 12 is calculated by the torque command value calculation device 10. a torque command value T _o1 that calculates the intermediate damping torque signal T _a1 attenuate. Note that the intermediate damping torque signal T _a1, of the attenuation command signal to attenuate the torque command value T _o1 the torque command value calculating unit 10 is calculated, and the attenuation degree of the torque command value T _o1 (torque command signal) is minimal It is the largest intermediate size.

Here, when the steering angle deviation δθ is less than the steering angle deviation coefficient ξ and the current steering angle θ does not pass the target steering angle θ ^* , the current steering angle θ becomes the target steering angle θ ^* . In the state of changing in the approaching direction, the current steering angle θ does not match the target steering angle θ ^* . This is a state where the steering angle deviation δθ tends to be reduced.
That is, the torque command attenuation circuit 12 is configured so that the degree of attenuation of the torque command signal is larger than a preset degree of attenuation when the steering angle deviation δθ calculated by the steering angle deviation calculation circuit 6 tends to decrease. Attenuation command signal is calculated. Specifically, an attenuation command signal (intermediate damping torque signal T _a1 ) in which the degree of attenuation of the torque command signal (torque command value T _o1 ) is larger than the minimum damping torque signal T _min1 is calculated.

Here, the “preset attenuation degree” is a value set in advance according to the vehicle speed of the host vehicle, for example, and is set to be larger as the vehicle speed is lower. The “predetermined degree of attenuation” may be set in advance according to the vehicle characteristics (steering characteristics, etc.) of the host vehicle, for example.
Here, the calculation of the intermediate damping torque signal _Ta1 is performed with reference to the direction of rotation of the steering wheel by the driver of the host vehicle.

Specifically, when the rotation direction of the steering wheel is rightward, the damping torque coefficient C ₁ (C ₁₁ , C _h1 ) having the value shown in FIG. 2B and the following equation (5) _{Is used} to calculate the intermediate damping torque signal _Ta1 . Note that the case where the rotation direction of the steering wheel is the right direction corresponds to the direction of turning the host vehicle to the right ("right steering" shown in FIG. 2B). Further, “C _h1 ” shown in FIG. 2B is the maximum value of the damping torque coefficient C ₁ .

On the other hand, when the rotation direction of the steering wheel is the left direction, the damping torque coefficient C ₁ (C ₁₁ , C _h1 ) having the values shown in FIG. 2B and the following equation (6) are used. Then, the intermediate damping torque signal _Ta1 is calculated. The case where the rotation direction of the steering wheel is the left direction corresponds to the direction in which the host vehicle turns left ("left steering" shown in FIG. 2B).

Then, the torque command attenuation circuit 12 which calculates the intermediate damping torque signal T _a1 is the torque command value T _o1 the torque command value calculating unit 10 is calculated, by adding the intermediate damping torque signal T _a1, torque attenuation command value T Generate ₁ In this case, the torque attenuation command value T ₁ is a value represented by the following equation (7).
T ₁ = T _o1 + T _a1 (7)

On the other hand, as a result of comparing the current steering angle θ and the target steering angle θ ^* , when the current steering angle θ passes the target steering angle θ ^* , the torque command attenuation circuit 12 calculates the maximum attenuation torque signal T _max1 . To do.
Here, “when the current steering angle θ passes the target steering angle θ ^* ” means that the current steering angle θ has passed the target steering angle θ ^* and the current steering angle θ is the target steering angle θ ^*. This includes a case where the current steering angle θ has changed in a direction away from the target steering angle θ ^* after passing through. Further, in the process of the theta current steering angle passes through a target steering angle theta ^*, when the theta current steering angle is equal to the target steering angle theta ^* is a time when the steering angle deviation .delta..theta (state deviance) becomes 0 Become.

The maximum damping torque signal T _max1 is the damping command signal that attenuates the torque command value T _o1 calculated by the torque command value calculation device 10, and the degree of attenuation of the torque command value T _o1 (torque command signal) is the largest. Is.
Then, the torque command attenuation circuit 12, the maximum attenuation torque signal T _max1 calculated, and added to the torque command value T _o1 the torque command value calculating unit 10 is calculated, to generate a torque attenuation command value T _1. In this case, the torque attenuation command value T ₁ is a value represented by the following equation (8).
T ₁ = T _o1 + T _max1 (8)

In the present embodiment, as an example, the maximum damping torque signal T _max1 is calculated using the damping torque coefficient C ₁ (C _h1 ) having the value shown in FIG. 2B and the following equation (9). The case where it does is demonstrated.
T _max1 = C _h1 × θ ' ₁ (9)
Here, when the steering angle deviation δθ is less than the steering angle deviation coefficient ξ and the current steering angle θ passes the target steering angle θ ^* , the steering angle deviation δθ decreases to zero. And a state in which the steering angle deviation δθ has increased from a state in which the steering angle deviation δθ has become zero.

That is, the torque command attenuation circuit 12, as the attenuation degree of the torque command signal (torque command value T _o1) is maximized, the steering angular speed theta _'1, damping torque coefficient is the maximum value among the preset coefficient C _h1 is integrated to calculate an attenuation command signal (maximum attenuation torque signal T _max1 ). Here, the calculation of the maximum damping torque signal T _max1 is performed when the steering angle deviation δθ (state deviation) becomes zero. In addition to this, the calculation of the maximum damping torque signal T _max1 is performed in a state where the steering angle deviation δθ has increased since the steering angle deviation δθ became zero.

By the above, the torque command attenuation circuit 12 in accordance with the steering angular velocity theta _'1, so that the attenuation degree of the torque command value T _o1 (torque command signal) changes, the attenuation command signal _{(T min1, T a1, T} max1 ) Is calculated (see formulas (4) to (6) and (9)).
The EPS 14 is a known electric power steering, and has an electric motor that can output a steering assist torque to the steering wheel.

Further, EPS14, based on the command signal input from the torque command attenuation circuit 12, and controls the electric motor, the steering assist torque corresponding to the torque damping command value T ₁ which torque command attenuator 12 is generated, the steering wheel Output to.
Normally, the control of the electric motor performed by the EPS 14 is performed by controlling the current supplied to the electric motor. Also in this embodiment, the electric motor is controlled by controlling the current supplied to the electric motor, and the steering assist torque corresponding to the torque attenuation command value T ₁ is output to the steering wheel.

(Operation)
Next, an example of the operation performed by the steering assist device 1 of the present embodiment will be described using FIG. 3 with reference to FIGS. 1 and 2.
FIG. 3 is a flowchart showing processing performed by the steering assist device 1 of the present embodiment.
The flowchart shown in FIG. 3 starts from a state in which the host vehicle is running and the driver for operating the steering assist device 1 is operated (ON) by the driver of the host vehicle (“START” shown in FIG. 3). ").

When the steering assist device 1 is operated, the target steering angle calculation device 2 calculates the target steering angle θ ^* at every predetermined sampling time such as every 10 [msec] (“target steering angle calculation shown in step S100”). ”) (Step S100). The target steering angle calculating device 2 calculates the target steering angle theta ^* the information signal including the calculated target steering angle theta ^*, and outputs to the steering angle deviation calculation circuit 6. When the target steering angle θ ^* is calculated in step S100, the processing performed by the steering assist device 1 proceeds to step S102.

  In step S102, the steering angle sensor 4 detects the current steering angle θ by the driver ("steering angle detection" shown in step S102). Then, the steering angle sensor 4 that has detected the current steering angle θ outputs an information signal including the detected current steering angle of the steering wheel to the steering angle deviation calculation circuit 6. In step S102, when the current steering angle θ is detected, the process performed by the steering assist device 1 proceeds to the process in step S104.

In step S104, the steering angle deviation calculation circuit 6 calculates a steering angle deviation δθ that is the difference between the target steering angle θ ^* and the current steering angle θ (“steering angle deviation calculation” shown in step S104). Then, the steering angle deviation calculation circuit 6 that has calculated the steering angle deviation δθ outputs an information signal including the calculated steering angle deviation δθ to the torque command value calculation device 10 and the torque command attenuation circuit 12. When the steering angle deviation δθ is calculated in step S104, the processing performed by the steering assist device 1 proceeds to step S106.

In step S106, the torque command value calculator 10 calculates the torque command value _To1 ("torque command value _To1 calculation" shown in step S106). Then, the torque command value calculating unit 10 which calculates the torque command value T _o1 is an information signal including the torque command value T _o1 calculated, and outputs the torque command damping circuit 12. When the torque command value _To1 is calculated in step S106, the processing performed by the steering assist device 1 proceeds to step S108.

In step S108, the steering angular velocity sensor 8 detects the steering angular velocity θ ′ ₁ (“steering angular velocity detection” shown in step S108). Then, the steering angular velocity theta 'steering angular velocity sensor 8 detecting the _1, the steering angular velocity theta detects' the information signal containing ₁ to output to the torque command damping circuit 12. When the steering angular velocity θ ′ ₁ is detected in step S108, the processing performed by the steering assist device 1 proceeds to step S110.

In step S110, the steering angle deviation δθ calculated by the steering angle deviation calculation circuit 6 by the torque command attenuation circuit 12 is less than the steering angle deviation coefficient ξ (“steering angle deviation <ξ?” Shown in step S110). Determine whether.
If it is determined in step S110 that the steering angle deviation δθ is greater than or equal to the steering angle deviation coefficient ξ (“NO” in the figure), the processing performed by the steering assist device 1 proceeds to step S112.

On the other hand, if it is determined in step S110 that the steering angle deviation δθ is less than the steering angle deviation coefficient ξ (“YES” shown in the figure), the processing performed by the steering assist device 1 proceeds to step S114.
In step S112, the torque command attenuating circuit 12 to generate a torque attenuation command value T ₁ that includes a command signal output to EPS14, a command signal including a torque attenuation command value T ₁ that the generated outputs to EPS14.

Here, the torque attenuation command value T ₁ is generated (“T ₁ = T _o1 + T _min1 ” shown in step S112) using the above-described equation (3).
In step S112, when a command signal including the torque attenuation command value T ₁ (= T _o1 + T _min1 ) is output to the EPS 14, the processing performed by the steering assist device 1 proceeds to step S122.

In step S114, it is determined whether or not the current steering angle θ detected in step S102 has passed the target steering angle θ ^* calculated in step S100 (“pass the target steering angle?” Shown in step S114). The determination performed in step S114 is performed when the current steering angle θ detected in step S102 rotates in one direction toward the target steering angle θ ^* calculated in step S100.

If it is determined in step S114 that the current steering angle θ does not pass the target steering angle θ ^* (“NO” shown in the figure), the processing performed by the steering assist device 1 proceeds to step S116.
On the other hand, if it is determined in step S114 that the current steering angle θ has passed the target steering angle θ ^* (“YES” in the figure), the processing performed by the steering assist device 1 proceeds to step S120.

In step S116, the torque command attenuation circuit 12 calculates an intermediate damping torque signal _Ta1 ("calculation of damping torque _Ta1 " shown in step S116). When the intermediate damping torque signal _Ta1 is calculated in step S116, the processing performed by the steering assist device 1 proceeds to step S118.
At step S118, the the torque command attenuating circuit 12 to generate a torque attenuation command value T ₁ that includes a command signal output to EPS14, a command signal including a torque attenuation command value T ₁ that the generated outputs to EPS14.

Here, the torque attenuation command value T ₁ is generated using the above-described equation (7) (“T ₁ = T _o1 + T _a1 ” shown in step S118).
In step S118, when a command signal including the torque attenuation command value T ₁ (= T _o1 + T _a1 ) is output to the EPS 14, the processing performed by the steering assist device 1 proceeds to step S122.
In step S120, the torque command attenuating circuit 12 to generate a torque attenuation command value T ₁ that includes a command signal output to EPS14, a command signal including a torque attenuation command value T ₁ that the generated outputs to EPS14.

Here, the torque attenuation command value T is generated using the above-described equation (8) (“T ₁ = T _o1 + T _max1 ” shown in step S120).
In step S120, when a command signal including the torque attenuation command value T ₁ (= T _o1 + T _max1 ) is output to the EPS 14, the processing performed by the steering assist device 1 proceeds to step S122.
In step S122, the current supplied to the electric motor is controlled based on the command signal input from the torque command attenuation circuit 12 in EPS14. Thus, in step S122, as the steering assist torque is a torque command attenuation circuit 12 corresponds to the torque damping command value T ₁ generated is outputted to the steering wheel, "controls the EPS" shown in the control (step S122 the EPS14 )

At this time, when the processing performed by the steering assist device 1 shifts from step S112 to step S122 described above, the degree of attenuation of the torque command value _To1 is minimized, so that the steering assist torque output to the steering wheel is maximum. The value reflects the degree of attenuation.
When the steering assist torque output to the steering wheel has a value that reflects the maximum degree of attenuation, a large steering assist torque is provided to the driver of the host vehicle via the steering wheel. Therefore, even if the current travel route of the host vehicle is away from the target travel route and the host vehicle is likely to deviate from the travel lane, it is possible to reduce the burden of the steering operation. The host vehicle can be positioned in the travel lane.

Further, when the processing performed by the steering assist device 1 proceeds from step S118 described above to step S122, the degree of attenuation of the torque command value _To1 is greater than the minimum value, and thus the steering assist torque output to the steering wheel. Is smaller than the maximum value.
When the steering assist torque output to the steering wheel is smaller than the maximum value, the driver of the host vehicle is provided with a steering assist torque smaller than the maximum value via the steering wheel. For this reason, an appropriate steering assist torque is provided to bring the current travel route of the host vehicle closer to the target travel route, and the burden of the steering operation can be reduced, and the host vehicle is placed in the travel lane. It becomes possible to position.

When the process performed by the steering assist device 1 shifts from step S120 described above to step S122, the degree of attenuation of the torque command value _To1 is maximized, and therefore the steering assist torque output to the steering wheel is the minimum value. It becomes.
When the steering assist torque output to the steering wheel becomes a minimum value, a small steering assist torque is provided to the driver of the host vehicle via the steering wheel. For this reason, after the current travel route of the host vehicle is set as the target travel route, a steering assist torque that can suppress the travel route of the host vehicle from moving away from the target travel route is provided, and the steering operation load is reduced. It becomes possible to reduce.

Controls EPS14 In step S122, the steering assist torque corresponding to the torque damping command value T ₁ which torque command attenuator 12 is generated, and outputs to the steering wheel, processing the steering assistance apparatus 1 performs the processing of step S100 Return.
Note that, as described above, the steering support method implemented by the operation of the steering support device 1 of the present embodiment reduces the state divergence, which is the divergence between the target state of the host vehicle and the current state of the host vehicle. Is output to the steering wheel. At this time, the steering assist torque is attenuated so that the attenuation degree of the steering assist torque is larger than a preset attenuation degree in a state where the calculated state deviation degree tends to be reduced. In addition to this, the steering assist torque is attenuated so that the degree of attenuation of the steering assist torque is equal to or less than a preset attenuation degree in a state where the calculated state divergence degree tends to increase.

  Thus, the target steering angle calculation device 2 forms a target state providing unit that provides the target state of the host vehicle, and the steering angle sensor 4 detects the current state that is the current state of the host vehicle. Is forming. Similarly, the steering angle deviation calculation circuit 6 forms a state divergence degree calculating means for calculating a state divergence degree that is a divergence degree between the target state calculated by the target state providing means and the current state detected by the current state detecting means. doing.

The steering angular velocity sensor 8 forms steering angular velocity detecting means for detecting the current rotational angular velocity of the steering wheel of the host vehicle as the steering angular velocity. Similarly, the torque command value calculation device 10 forms steering assist torque calculation means for calculating a steering assist torque for reducing the state deviation degree calculated by the state deviation degree calculation means.
The torque command attenuation circuit 12 calculates an attenuation command signal for attenuating the steering assist torque calculated by the steering assist torque calculation means, and forms a steering assist torque attenuation means for attenuating the steering assist torque based on the calculated attenuation command signal. doing. Similarly, the EPS 14 forms steering characteristic control means for outputting the steering assistance torque calculated by the steering assistance torque calculation means to the steering wheel.

(Effects of the first embodiment)
(1) When the steering assist torque attenuating means is in a state in which the degree of state divergence tends to decrease, an attenuation command signal is calculated so that the degree of attenuation of the steering assist torque is greater than a preset degree of attenuation. Further, in a state where the degree of state divergence tends to increase, the attenuation command signal is calculated so that the attenuation degree of the steering assist torque is equal to or less than a preset attenuation degree.
For this reason, when the driver of the host vehicle steers the steering wheel, a steering operation with a low steering load is possible. Further, the closer the current state of the host vehicle is to the target state, the stronger the damping force on the steering assist torque acts on the steering wheel.
As a result, it becomes possible to quickly converge the steering angle of the host vehicle to the target steering angle, and in situations where it is desired to generate a strict steering angle or where the target steering angle is to be realized with quick steering, It is possible to improve the reliability of the steering support.

(2) Since the target state is the target steering angle, the current state is the current steering angle, and the degree of state divergence is the difference between the target steering angle and the current steering angle, the difference between the target steering angle and the current steering angle is quickly converged. It is possible to provide a steering assist device that can be operated to the driver of the host vehicle.
As a result, it is possible to improve the reliability of the steering support in a situation where it is desired to realize the target steering angle with quick steering.

(3) The steering angular velocity detection means detects the current rotational angular velocity of the steering wheel as the steering angular speed, and the steering assist torque attenuation means determines the degree of attenuation of the steering assist torque according to the steering angular speed detected by the steering angular speed detection means. The attenuation command signal is calculated so that changes.
As a result, it is possible to provide the driver of the host vehicle with the steering assist device 1 that has a smooth steering operation and is less uncomfortable in the steering operation.

(4) The steering assist torque attenuation means calculates an attenuation command signal by adding a preset coefficient to the steering angular speed detected by the steering angular speed detection means. In addition, the steering assist torque attenuating means calculates the attenuation command signal so that the degree of attenuation of the steering assist torque is maximized when the state deviation degree calculated by the state deviation degree calculating means becomes zero. .
As a result, the driver of the host vehicle can understand that the host vehicle has reached the target state by a tactile sensation generated when the steering wheel is operated.

(5) The maximum value among the preset coefficients is used as the preset coefficient to be integrated with the steering angular speed detected by the steering angular speed detecting means. This is performed only when the state divergence increases from the time when the state divergence becomes 0, in addition to the time when the state divergence calculated by the state divergence calculating means decreases to 0.
As a result, the driver of the host vehicle can understand that the host vehicle has passed the target state with a tactile sensation generated when operating the steering wheel.

(6) In the steering support method of the present embodiment, steering assist torque for reducing the degree of state deviation, which is the degree of deviation between the target state of the host vehicle and the current state of the host vehicle, is output to the steering wheel. At this time, the steering assist torque is attenuated so that the attenuation degree of the steering assist torque is larger than a preset attenuation degree in a state where the calculated state deviation degree tends to be reduced. In addition to this, the steering assist torque is attenuated so that the degree of attenuation of the steering assist torque is equal to or less than a preset attenuation degree in a state where the calculated state divergence degree tends to increase.

For this reason, when the driver of the host vehicle steers the steering wheel, steering with a low steering load is possible. Further, as the current state of the host vehicle becomes closer to the target state, the damping force to the steering assist torque acts more strongly on the steering wheel.
As a result, it becomes possible to quickly converge the steering angle of the host vehicle to the target steering angle, and in situations where it is desired to generate a strict steering angle or where the target steering angle is to be realized with quick steering, It is possible to improve the reliability of the steering support.

(Modification)
(1) In the steering assist device 1 of the present embodiment, the torque command attenuation circuit 12 is configured such that the degree of attenuation of the torque command value _To1 changes according to the steering angular velocity θ ′ ₁ detected by the steering angular velocity sensor 8. Although the attenuation command signal is calculated, the present invention is not limited to this. That is, the attenuation command signal may be calculated without using the steering angular velocity θ ′ ₁ detected by the steering angular velocity sensor 8. In this case, the configuration of the steering assist device 1 may be a configuration that does not include the steering angular velocity sensor 8.

(2) In the steering assist device 1 of the present embodiment, the torque command attenuation circuit 12 causes the maximum attenuation torque signal so that the degree of attenuation of the torque command value _To1 is maximized _when the steering angle deviation δθ becomes zero. Although _Tmax1 was calculated, it is not limited to this. That is, regardless of whether or not the steering angle deviation δθ becomes zero, the attenuation command signal may be calculated based on the determination as to whether or not the steering angle deviation δθ is less than the steering angle deviation coefficient ξ.

(3) In the steering assist device 1 of the present embodiment, when the steering angle deviation δθ increases from the time when the steering angle deviation δθ becomes 0 in addition to the time when the steering angle deviation δθ decreases to 0, Although the damping torque coefficient C _h1 is integrated with the steering angular velocity θ ′ ₁ , the present invention is not limited to this. That is, when the steering angle deviation δθ increases from the time when the steering angle deviation δθ becomes 0 in addition to the time when the steering angle deviation δθ decreases to 0, a value exceeding the damping torque coefficient _{Ch 1} is set to a value that exceeds the steering angular velocity. θ 'may be credited to _1.

(4) In the steering assist device 1 of the present embodiment, the driver operates the steering assist device 1 by operating a switch that operates the steering assist device 1 while the host vehicle is traveling. However, the present invention is not limited to this. Not what you want. That is, for example, with reference to an image obtained by imaging the environment around the host vehicle, it is determined whether or not the road (running path) on which the host vehicle is traveling is a road on which the steering assist device 1 is preferably operated. The steering assist device 1 may be operated regardless of the driver's operation. In this case, an image obtained by imaging the environment around the host vehicle is acquired using, for example, a CCD camera included in the imaging circuit 16.

(Second embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. In addition, description may be abbreviate | omitted about the structure similar to 1st embodiment mentioned above.
(Constitution)
FIG. 4 is a block diagram showing a configuration of the steering assist device 1 of the present embodiment.
As shown in FIG. 4, the steering assist device 1 of the present embodiment includes a magnetic sensor 24, a target route detection circuit 26, a lateral position deviation calculation circuit 28, a steering angular velocity sensor 8, and a torque command value calculation device 10. And a torque command attenuation circuit 12 and an electric motor 30.

  As shown in FIG. 5, a plurality of magnetic sensors 24 are arranged on the front side in the vehicle front-rear direction of the host vehicle V equipped with the steering assist device 1 (for example, on the front side with respect to the front wheels). 24 are arranged in a line along the vehicle width direction of the host vehicle V. FIG. 5 is a diagram showing a schematic configuration of the host vehicle V provided with the steering assist device 1 of the present embodiment. Further, in FIG. 5, the center line in the vehicle width direction of the host vehicle V is indicated by a broken line with a symbol “CL”.

Each magnetic sensor 24 reacts to a magnetic nail (not shown) embedded in a travel path (road) on which the host vehicle V travels, and outputs an information signal including the strength of magnetic force proportional to the distance from the magnetic nail. Output to the target path detection circuit 26. In FIG. 5, the strength of the magnetic force detected by each magnetic sensor 24 is continuously shown along the vehicle width direction of the host vehicle V.
In the present embodiment, a plurality of magnetic nails that continuously generate magnetism are embedded at a predetermined interval along the length direction of the traveling road in the center of the traveling path on which the host vehicle V travels. It is assumed that the road is.
Based on the information signal input from each magnetic sensor 24, the target route detection circuit 26 detects the route that the host vehicle V should follow, that is, the target travel route that is the target travel route of the host vehicle V, and this detection. The information signal including the target travel route is output to the lateral position deviation calculation circuit 28.

  When detecting the target travel route, specifically, the information signals output from the magnetic sensors 24 are compared, and the magnetic sensor 24 that outputs the strongest information signal is identified from the magnetic sensors 24. And the position of the magnetic sensor 24 which output the strongest information signal is detected as one point on the target travel route. This is because the position of the magnetic sensor 24 that outputs the strongest information signal among the magnetic sensors 24 overlaps with the magnetic nail, that is, the center of the traveling path on which the host vehicle V travels in the vertical direction. In FIG. 5, among the magnetic sensors 24, a set of points that overlap in the vertical direction with the magnetic sensor 24 that output the strongest information signal, that is, a line indicating the target travel route is denoted by a reference sign “TL”. This is indicated by the solid line attached.

  The lateral position deviation calculation circuit 28 is based on the information signal input from the target route detection circuit 26 and the position of the magnetic sensor 24 that has output the strongest information signal among the magnetic sensors 24 and the vehicle width direction of the host vehicle V. A distance in the vehicle width direction from the center line CL is calculated as a lateral position deviation. In the following description, the lateral position deviation may be described as “lateral position deviation d” (see FIG. 5). Further, in FIG. 5, the magnetic sensor 24 that outputs the strongest information signal among the magnetic sensors 24 is denoted by reference numeral “24max”. Therefore, as shown in FIG. 5, the lateral position deviation d is the distance in the vehicle width direction of the host vehicle V between the line TL indicating the target travel route and the center line CL in the vehicle width direction of the host vehicle V. .

Then, the lateral position deviation calculation circuit 28 that has calculated the lateral position deviation d outputs an information signal including the calculated lateral position deviation d to the torque command value calculation device 10.
Therefore, in the present embodiment, the target state of the host vehicle V is set as a target travel route that is a target travel route of the host vehicle V.
In the present embodiment, the current state, which is the current state of the host vehicle V, is set as a relative position on the current travel route of the host vehicle V with respect to the target travel route.

Similarly, in the present embodiment, the state deviation degree, which is the degree of deviation between the target state and the current state, is set as the lateral position deviation d, which is the distance from the current relative position of the host vehicle V to the target traveling route. And
As in the first embodiment described above, the steering angular velocity sensor 8 detects a steering angular velocity that is a rotational angular velocity at the time of steering of the steering wheel by the driver of the host vehicle V, and an information signal including the detected steering angular velocity. Is output to the torque command attenuation circuit 12. In the following description, the steering angular velocity may be described as “steering angular velocity θ ′ ₂ ”.

The torque command value calculation device 10 calculates a torque command signal that is a command value of the steering assist torque output to the steering wheel based on the information signal input from the lateral position deviation calculation circuit 28. Then, the torque command value calculation device 10 generates the calculated torque command signal and outputs it to the torque command attenuation circuit 12. In the following description, the torque command value may be described as “torque command value _To2 ”.

In the present embodiment, as an example, a case where the torque command value _To2 is calculated using the map shown in FIG. _6A and the following equation (10) will be described. FIG. 6 is an explanatory diagram for explaining an output rule of the torque command value _To2 output via the torque command value calculation device 10 and the torque command attenuation circuit 12.
T _o2 = K ₂ × d ² (10)
Here, in the above formula (10), when d <0, K ₂ <0. Similarly, when d> 0, K ₂ > 0.

In the above formula (10), “K ₂ ” is a coefficient corresponding to the convergence speed to the target steering angle, which is stored in advance in the torque command value calculation device 10. This coefficient is set as a fixed constant or a variable corresponding to the vehicle speed or the like. Further, as shown in the above equation (10), the torque command value _To2 is a value proportional to the square of the lateral position deviation d.
The torque command attenuation circuit 12 calculates an attenuation command signal for attenuating the torque command value _To2 calculated by the torque command value calculation device 10 based on the information signals input from the steering angular velocity sensor 8 and the torque command value calculation device 10. . Then, by generating a torque attenuation command value obtained by attenuating the torque command value T _o2 The calculated attenuation command signal, and outputs to the electric motor 30.

Here, when calculating the attenuation command signal, the torque command attenuation circuit 12 performs branching based on the comparison described below.
Specifically, based on the value of the lateral position deviation d calculated by the lateral position deviation calculating circuit 28, it is determined whether or not the host vehicle V has passed the target travel route. Then, according to the determination result, one type of torque attenuation command value T ₂ out of the two types included in the command signal output to the electric motor 30 is generated.
Torque command attenuation circuit to generate a torque attenuation command value T ₂ 12 is a command signal including a torque attenuation command value T ₂ which is the product, and outputs to the electric motor 30.

Hereinafter, based on the value of the lateral position deviation d calculated by the lateral position deviation calculating circuit 28, it is determined whether or not the host vehicle V has passed the target travel route, and two types of torque generated according to the determination result. The relationship with the attenuation command value T ₂ will be described.
Based on the value of the lateral position deviation d, whether or not the host vehicle V has passed the target travel route is determined by the direction in which the lateral position deviation d decreases as a result of the host vehicle V moving in the right or left direction. This is done on the assumption that it has changed.

In this case, when the host vehicle V reaches the target travel route, the lateral position deviation d temporarily disappears (d = 0), and the lateral position deviation continues by continuing to move in the same direction. It is detected whether or not d starts to increase (d> 0). That is, it is detected whether or not the host vehicle V further moves in the same direction after passing the point (zero point) where the lateral position deviation d on the target travel route is “0”.
Then, when the lateral position deviation d starts to increase (d> 0) from the state where the lateral position deviation d temporarily disappears (d = 0), it is determined that the host vehicle V has passed the target travel route. .

If it is determined that the vehicle V has passed the target traveling path, the torque command attenuation circuit 12 calculates the intermediate damping torque signal T _a2 to attenuate the torque command value T _o2 the torque command value calculating unit 10 is calculated. Note that the intermediate damping torque signal T _a2, of the attenuation command signal to attenuate the torque command value T _o2 the torque command value calculating unit 10 is calculated, and the attenuation degree of the torque command value T _o2 (torque command signal) is minimal It is the largest intermediate size.

Here, the calculation of the intermediate damping torque signal _Ta2 is performed with reference to the moving direction of the host vehicle V.
Specifically, the 6 damping torque coefficient of the values shown in (b) C ₂ (C _l2), using equation (11) below, to calculate the intermediate damping torque signal T _a2.
T _a2 = C _l2 × θ ′ ₂ (11)
Then, the torque command attenuation circuit 12 which calculates the intermediate damping torque signal T _a2 is the torque command value T _o2 the torque command value calculating unit 10 is calculated, by adding the intermediate damping torque signal T _a2, torque attenuation command value T ₂ is generated. In this case, the torque attenuation command value T ₂ is a value represented by the following equation (12).
T ₂ = T _o2 + T _a2 (12)

On the other hand, when it is determined that the host vehicle V does not pass through the target travel route, the torque command attenuation circuit 12 calculates the maximum attenuation torque signal T _max2 . The maximum damping torque signal T _max2 is the damping command signal that attenuates the torque command value T _o2 calculated by the torque command value calculation device 10, and the degree of attenuation of the torque command value T _o2 (torque command signal) is the maximum. Is.

Then, the torque command attenuation circuit 12, the maximum attenuation torque signal T _max2 calculated, and added to the torque command value T _o2 the torque command value calculating unit 10 is calculated, to generate a torque attenuation command value T _2. In this case, the torque attenuation command value T ₂ is a value represented by the following equation (13).
T ₂ = T _o2 + T _max2 (13)
In the present embodiment, as an example, the maximum damping torque signal T _max2 is calculated using the damping torque coefficient C ₂ (C _h2 ) having the value shown in FIG. 6B and the following equation (14). The case where it does is demonstrated.
T _max2 = C _h2 × θ ' ₂ (14)

The electric motor 30 has a configuration of a known electric power steering, and is configured to output a steering assist torque to the steering wheel by controlling a supplied current.
The electric motor 30, based on the command signal input from the torque command attenuation circuit 12, and controls the electric motor, the steering assist torque corresponding to the torque damping command value T ₂ the torque command attenuator 12 is generated, Output to the steering wheel.

(Operation)
Next, an example of an operation performed by the steering assist device 1 of the present embodiment will be described with reference to FIGS. 4 to 6 and FIG.
FIG. 7 is a flowchart showing processing performed by the steering assist device 1 of the present embodiment.
The flowchart shown in FIG. 7 starts from a state in which the host vehicle is running and the driver for operating the steering assist device 1 is operated (ON) by the driver of the host vehicle (“START” shown in FIG. 7). ").
When the steering assist device 1 is operated, the target route detection circuit 26 detects a target travel route that the host vehicle should follow, for example, every predetermined sampling time, such as every 10 [msec] (step S200). Then, the target route detection circuit 26 that has detected the target travel route outputs an information signal including the detected target travel route to the lateral position deviation calculation circuit 28.

The lateral position deviation calculation circuit 28 that has received the input of the information signal including the target travel route calculates the lateral position deviation d (step S200). Then, the lateral position deviation calculation circuit 28 that has calculated the lateral position deviation d outputs an information signal including the calculated lateral position deviation d to the torque command value calculation device 10.
Therefore, in step S200, the target route detection circuit 26 detects the target travel route, and further, the lateral position deviation calculation circuit 28 calculates the lateral position deviation d (see “Target Route Detection and Lateral Position Deviation” shown in Step S200). )). When the target travel route is detected and the lateral position deviation d is calculated in step S200, the processing performed by the steering assist device 1 proceeds to step S202.

In step S202, the torque command value calculating unit 10, calculates the torque command value T _o2 (shown in step S202, "torque command value T _o2 calculation") to. Then, the torque command value calculating unit 10 which calculates the torque command value T _o2 is an information signal including the torque command value T _o2 calculated, and outputs the torque command damping circuit 12. When the torque command value _To2 is calculated in step S202, the process performed by the steering assist device 1 proceeds to the process of step S204.

In step S204, the steering angular velocity sensor 8 detects the steering angular velocity θ ′ ₂ (“steering angular velocity detection” shown in step S204). Then, the steering angular velocity theta 'steering angular velocity sensor 8 detecting the _2, the steering angular velocity theta detects' an information signal including _two outputs to the torque command damping circuit 12. When the steering angular velocity θ ′ ₂ is detected in step S204, the processing performed by the steering assist device 1 proceeds to step S206.

In step S206, whether or not the vehicle V has further moved in the same direction after passing through the point (zero point) where the lateral position deviation d on the target travel route is “0” by the torque command attenuation circuit 12. ("Does it pass the zero point?" Shown in step S206) is detected. Thereby, in step S206, it is determined whether the own vehicle V has passed the target travel route.
If it is determined in step S206 that the host vehicle V has not passed the target route ("NO" shown in the figure), the processing performed by the steering assist device 1 proceeds to step S208.

On the other hand, if it is determined in step S206 that the host vehicle V has passed the target route ("YES" shown in the figure), the processing performed by the steering assist device 1 proceeds to step S212.
In step S208, the torque command attenuation circuit 12 calculates the intermediate damping torque signal _Ta2 ("damping torque _Ta2 calculation" shown in step S208). When the intermediate damping torque signal _Ta2 is calculated in step S208, the processing performed by the steering assist device 1 proceeds to step S210.

In step S210, the torque command attenuating circuit 12 to generate a torque attenuation command value T ₂ including a command signal to be output to the electric motor 30, a command signal including a torque attenuation command value T ₂ which is the product, to the electric motor 30 Output.
Here, the torque attenuation command value T ₂ is generated using the above-described equation (12) (“T ₂ = T _o2 + T _a2 ” shown in step S210).
In step S210, and outputs a command signal including a torque attenuation command value T ₂ to the electric motor 30, process steering assist device 1 performs, the process proceeds to step S214.

At step S212, the the torque command attenuating circuit 12 to generate a torque attenuation command value T ₂ including a command signal to be output to the electric motor 30, a command signal including a torque attenuation command value T ₂ which is the product, to the electric motor 30 Output.
Here, the torque attenuation command value T ₂ is generated using the above-described equation (13) (“T ₂ = T _o2 + T _max2 ” shown in step S212).
In step S212, the and outputs a command signal including a torque attenuation command value T ₂ to the electric motor 30, process steering assist device 1 performs, the process proceeds to step S214.

In step S <b> 214, a current controlled based on the command signal input from the torque command attenuation circuit 12 is supplied to the electric motor 30. Thus, in step S214, as the steering assist torque corresponding to the torque damping command value T ₂ the torque command attenuator 12 was generated is output to the steering wheel, controls the electric motor 30 (shown in step S214, "the electric motor Control ").
At this time, when the processing performed by the steering assist device 1 shifts from step S210 to step S214 described above, the degree of attenuation of the torque command value _To2 becomes larger than the minimum value, and thus the steering assist output to the steering wheel. Torque is smaller than the maximum value.

When the steering assist torque output to the steering wheel is smaller than the maximum value, the driver of the host vehicle is provided with a steering assist torque smaller than the maximum value via the steering wheel. For this reason, an appropriate steering assist torque is provided to bring the current travel route of the host vehicle closer to the target travel route, and the burden of the steering operation can be reduced, and the host vehicle is placed in the travel lane. It becomes possible to position.
When the process performed by the steering assist device 1 shifts from step S212 to step S214 described above, the degree of attenuation of the torque command value _To2 is maximized, and therefore the steering assist torque output to the steering wheel is the minimum value. It becomes.

When the steering assist torque output to the steering wheel becomes a minimum value, a small steering assist torque is provided to the driver of the host vehicle via the steering wheel. For this reason, after the current travel route of the host vehicle is set as the target travel route, a steering assist torque that can suppress the travel route of the host vehicle from moving away from the target travel route is provided, and the steering operation load is reduced. It becomes possible to reduce.
And controls the electric motor 30 in step S214, the steering assist torque corresponding to the torque damping command value T ₂ the torque command attenuator 12 is generated, and outputs to the steering wheel, the process of steering assist device 1 performs, in step S200 Return to processing.

  As described above, the combination of the magnetic sensor 24, the target path detection circuit 26, and the lateral position deviation calculation circuit 28 forms a combination of the above-described current state detection means, target state provision means, and state divergence calculation means. Similarly, the steering angular velocity sensor 8 forms the steering angular velocity detection means described above, and the torque command value calculation device 10 forms the steering assist torque calculation means described above. The torque command attenuation circuit 12 forms the steering assist torque attenuation unit described above, and the electric motor 30 forms the steering characteristic control unit described above.

(Effect of the second embodiment)
(1) In this embodiment, the target state is the target travel route, the current state is the relative position on the current travel route of the host vehicle with respect to the target travel route, and the state divergence is the distance from the relative position to the target travel route. It is said.
For this reason, it is possible to provide the driver of the host vehicle with a steering assist device that can quickly converge the relative distance between the target travel route and the current position of the host vehicle.
As a result, it is possible to provide the driver of the host vehicle with a steering support device that has less overshoot in the travel path of the host vehicle and can assist the steering operation for reliably following the travel route. . This is because when the driver requires strict steering, a strong torque is generated on the steering wheel in a direction to push the vehicle back to the target travel path so that the departure of the vehicle from the target path is minimized. Is particularly effective.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. In addition, description may be abbreviate | omitted about the structure similar to 1st embodiment mentioned above.
(Constitution)
FIG. 8 is a block diagram illustrating a configuration of the steering assist device 1 of the present embodiment.
As shown in FIG. 8, the steering assist device 1 of this embodiment includes a laser sensor 32, an obstacle detection circuit 34, an avoidance target point calculation circuit 36, and a direction angle calculation circuit 38. In addition to this, the steering assist device 1 of the present embodiment includes a steering angular velocity sensor 8, a torque command value calculation device 10, a torque command attenuation circuit 12, and an electric motor 30.

  For example, the laser sensor 32 is disposed in front of the host vehicle in the vehicle front-rear direction, and irradiates the front of the host vehicle with respect to the vehicle front-rear direction. The laser sensor 32 receives a laser beam reflected by an obstacle or the like on the travel route after the irradiation, and outputs an information signal including a time when the laser is irradiated and received and a direction in which the laser is received to the obstacle detection circuit. 34. The “obstacles” are, for example, obstacles, other vehicles, and pedestrians.

The obstacle detection circuit 34 detects an obstacle existing on the travel route of the host vehicle based on the information signal input from the laser sensor 32, and uses the detected information signal including the obstacle as an avoidance target point calculation circuit. To 36.
Here, when the obstacle detection circuit 34 detects an obstacle present on the traveling route of the host vehicle, first, the time of irradiation and reception of the laser included in the information signal input from the laser sensor 32 is determined. refer. Then, the distance between the host vehicle and the obstacle is calculated from the time lag between the laser irradiation time and the received time, and when the calculated distance is less than a predetermined distance, the obstacle on the traveling route of the host vehicle is calculated. Is determined to exist. The “predetermined distance” described above may be set in advance, or may be increased or decreased according to the traveling speed of the host vehicle.

  The avoidance target point calculation circuit 36 calculates an avoidance target point for moving the host vehicle when the host vehicle avoids an obstacle based on the information signal input from the obstacle detection circuit 34, and calculates the calculated avoidance. An information signal including the target point is output to the direction angle calculation circuit 38. The calculation of the avoidance target point is performed when the information signal input from the obstacle detection circuit 34 includes a result determined that an obstacle exists on the traveling route of the host vehicle.

Here, when an obstacle exists on the traveling route of the host vehicle, the traveling route for avoiding the obstacle exists on the right side or the left side of the traveling route of the host vehicle.
For this reason, when calculating the target point, after setting the avoidance direction for the own vehicle to avoid the obstacle, the avoidance target point that becomes the target position when passing the own vehicle in the set avoidance direction Is calculated.

Hereinafter, a procedure for setting an avoidance direction for the host vehicle to avoid an obstacle will be described.
When setting the avoidance direction, referring to the information signal output by the laser sensor 32, as shown in FIG. 9, the left and right ends (corner portions) of the obstacle OB as viewed from the host vehicle V are displayed. Calculate the position. Then, the angle α ₁ to the position of the left end of the obstacle OB and the angle to the position of the right end of the obstacle OB with respect to the traveling direction of the own vehicle V with respect to the center point CP of the own vehicle V α ₂ is detected, and the angle α ₁ is compared with the angle α ₂ . FIG. 9 is a diagram illustrating a relationship between the obstacle OB and the host vehicle V. Further, in FIG. 9, a line indicating the target travel route of the host vehicle V is indicated by a solid line with a reference “RL”, and a line indicating the current travel route of the host vehicle V is indicated by a reference “PL”. This is indicated by the solid line attached.

Then, as a result of comparing the angle α ₁ and the angle α ₂ , the side having the end with the smaller angle is set as the avoidance direction for the host vehicle V to avoid the obstacle OB. In the present embodiment, as an example, a case where α ₁ > α ₂ will be described as shown in FIG. In connection with this, this embodiment demonstrates the case where the avoidance direction for the own vehicle V to avoid the obstruction OB is set to the right direction.

Next, a procedure for calculating an avoidance target point that is a target position when passing the host vehicle V will be described.
When calculating the avoidance target point, as shown in FIG. 9, the vehicle V is set in the same direction as the set avoidance direction from the end (corner portion) of the obstacle OB on the same side as the avoidance direction. A position obtained by adding a length of 1/2 or more (w / 2 or more) of the vehicle width w is calculated as an avoidance target point. In the following description, the avoidance target point may be described as “avoidance target point P _t ” (see FIG. 9).

Direction angle calculating circuit 38 on the basis of the information signal input from the avoidance target point calculation circuit 36 calculates for the traveling direction of the host vehicle V, direction difference angle to avoidance target point P _t beta (see Fig. 9) The information signal including the calculated difference direction angle β is output to the torque command value calculation device 10.
Here, the difference direction angle β is calculated using the following equation (15), where “L” is the distance between the host vehicle V and the obstacle OB in the traveling direction of the host vehicle V (see FIG. 9). ).

Therefore, in the present embodiment, the target state of the host vehicle V is a target direction angle that is an angle to the travel route targeted by the host vehicle V with respect to the direction in which the host vehicle V has traveled.
In the present embodiment, the current state, which is the current state of the host vehicle V, is the current direction angle, which is the current angle of the host vehicle V with respect to the direction in which the host vehicle V is traveling.
Similarly, in the present embodiment, a state divergence degree that is a divergence degree between the target state and the current state is set as a difference direction angle β that is a difference between the target direction angle and the current direction angle.

As in the first embodiment described above, the steering angular velocity sensor 8 detects a steering angular velocity that is a rotational angular velocity at the time of steering of the steering wheel by the driver of the host vehicle V, and an information signal including the detected steering angular velocity. Is output to the torque command attenuation circuit 12. In the following description, the steering angular velocity may be described as “steering angular velocity θ ′ ₃ ”.

The torque command value calculation device 10 calculates a torque command signal that is a command value of the steering assist torque output to the steering wheel based on the information signal input from the lateral position deviation calculation circuit 28. Then, the torque command value calculation device 10 generates the calculated torque command signal and outputs it to the torque command attenuation circuit 12. In the following description, a torque command value, may be referred to as "torque command value T _o3".

In the present embodiment, as an example, the case where the torque command value is calculated using the map shown in FIG. 10A and the following equation (16) will be described. FIG. 10 is an explanatory diagram for explaining an output rule of a torque command value output via the torque command value calculation device 10 and the torque command attenuation circuit 12.
T _o3 = K ₃ × β (16)
In the above equation (16), “K ₃ ” is a coefficient corresponding to the convergence speed to the target steering angle, which is stored in advance in the torque command value calculation device 10. This coefficient is set as a fixed constant or a variable corresponding to the vehicle speed or the like.
Further, as shown in the above equation (16), the torque command value _To3 is a value proportional to the difference direction angle β.

Torque command attenuation circuit 12 on the basis of the information signal input from the steering angular velocity sensor 8 and the torque command value calculating unit 10 calculates the attenuation command signal to attenuate the torque command value T _o3 the torque command value calculating unit 10 is calculated . Then, a torque attenuation command value obtained by attenuating the torque command value _To3 is generated from the calculated attenuation command signal, and is output to the electric motor 30.
Here, when calculating the attenuation command signal, the torque command attenuation circuit 12 performs branching based on the comparison described below.

Specifically, the difference direction angle β calculated by the direction angle calculation circuit 38 is compared with a preset difference direction angle coefficient ψ shown in FIG. Also determined by the comparison result between the difference direction angle β and the differential direction angle coefficient [psi, the traveling direction of the host vehicle V, whether through the avoidance target point P _t.
The “difference direction angle coefficient ψ” is, for example, a coefficient used when generating a torque attenuation command value based on a state where the difference direction angle β is “0” as shown in FIG. The damping torque coefficient C ₃ ) is a threshold value that makes the maximum value (C _h3 ) or less. The “difference direction angle coefficient ψ” is set as a fixed constant or a variable according to the vehicle speed or the like.

Then, the comparison result between the difference direction angle β and the differential direction angle coefficient [psi, or, the traveling direction of the host vehicle V, depending on the avoidance of whether passing through the target point P _t determination result, one of the three types A torque attenuation command value T ₃ of a kind is generated.
Torque command attenuation circuit to generate a torque attenuation command value T ₃ 12 is a command signal including a torque attenuation command value T ₃ that this product is output to the electric motor 30.

Hereinafter, the comparison result of the difference direction angle β and the difference direction angle coefficient ψ, or the determination result of whether or not the traveling direction of the host vehicle V has passed the avoidance target point _Pt , and generated according to these results The relationship between the three types of torque attenuation command values T ₃ will be described.
When the difference direction angle β is equal to or greater than the difference direction angle coefficient ψ as a result of comparing the difference direction angle β and the difference direction angle coefficient ψ, the torque command attenuation circuit 12 calculates the torque command value calculated by the torque command value calculation device 10. It determines that there is no need to attenuate T _o3, the torque command value T _o3, generates a torque attenuation command value T _3. In this case, the torque attenuation command value T ₃ is a value represented by the following equation (17).
T ₃ = T _o3 (17)

On the other hand, if the difference direction angle β is less than the difference direction angle coefficient ψ as a result of comparing the difference direction angle β and the difference direction angle coefficient ψ, the torque command attenuation circuit 12 calculates the torque calculated by the torque command value calculation device 10. It is determined that the command value _To3 needs to be attenuated.
If it is determined that the need to attenuate the torque command value T _o3 there, the torque command attenuation circuit 12 from the information signal input from the steering angular velocity sensor 8, required to attenuate the torque command value T _o3, the steering angular velocity θ 'Detect ₃

The torque command attenuation circuit 12 that has detected the steering angular velocity θ ′ ₃ performs a turning motion for the host vehicle V to avoid the obstacle OB, and when the difference direction angle β is reduced along with the turning motion, traveling direction of the host vehicle V, it determines whether passed the avoidance target point P _t. That is, it is determined whether or not the traveling direction of the host vehicle V performing a turning motion to avoid the obstacle OB has passed a point (zero point) having a difference direction angle β of “0”.

Then, the traveling direction of the host vehicle V is performing a turning motion to avoid the obstacle OB is, if not passed the avoidance target point P _t, the torque command attenuation circuit 12, the torque command value calculating unit 10 a torque command value T _o3 calculated to calculate the intermediate damping torque signal T _a3 attenuate. Note that the intermediate damping torque signal T _a3, of the attenuation command signal to attenuate the torque command value T _o3 the torque command value calculating unit 10 is calculated, and the attenuation degree of the torque command value T _o3 (torque command signal) is minimal It is the largest intermediate size.

Here, the calculation of the intermediate damping torque signal T _a3, and damping torque coefficient C ₃ of the values shown in FIG. 10 (b), the a, using equation (18) below.
T _a3 = C ₃ × θ ′ ₃ (18)
Then, the torque command attenuation circuit 12 which calculates the intermediate damping torque signal T _a3 is the torque command value T _o3 the torque command value calculating unit 10 is calculated, by adding the intermediate damping torque signal T _a3, torque attenuation command value T Generates ₃ . In this case, the torque attenuation command value T ₃ is a value represented by the following equation (19).
T ₃ = T _o3 + T _a3 (19)

On the other hand, the traveling direction of the host vehicle V is performing a turning motion to avoid the obstacle OB is, if passing through the avoidance target point P _t, the torque command attenuation circuit 12, the maximum attenuation torque signal T _max3 calculate. Note that the maximum attenuation torque signal T _max3, among the attenuation command signal to attenuate the torque command value T _o3 the torque command value calculating unit 10 is calculated, the attenuation degree of the torque command value T _o3 (torque command signal) is maximum Is.

Then, the torque command attenuation circuit 12, the maximum attenuation torque signal T _max3 calculated, and added to the torque command value T _o3 the torque command value calculating unit 10 is calculated, to generate a torque attenuation command value T _3. In this case, the torque attenuation command value T ₃ is a value represented by the following equation (20).
T ₃ = T _o3 + T _max3 (20)
In the present embodiment, as an example, the maximum damping torque signal T _max3 is calculated using the damping torque coefficient C ₃ (C _h3 ) having the value shown in FIG. 10B and the following equation (21). The case where it does is demonstrated.
T _max3 = C _h3 + θ ' ₃ (21)

The electric motor 30 has a configuration of a known electric power steering, and is configured to output a steering assist torque to the steering wheel by controlling a supplied current.
The electric motor 30, based on the command signal input from the torque command attenuation circuit 12, and controls the electric motor, the steering assist torque corresponding to the torque damping command value T ₃ in which the torque command attenuator 12 is generated, Output to the steering wheel.

(Operation)
Next, an example of an operation performed by the steering assist device 1 of the present embodiment will be described with reference to FIGS. 8 to 10 and FIG. 11.
FIG. 11 is a flowchart showing processing performed by the steering assist device 1 of the present embodiment.
The flowchart shown in FIG. 11 starts from a state in which the host vehicle is running and the driver for operating the steering assist device 1 is operated (ON) by the driver of the host vehicle (“START” shown in FIG. 11). ").

  When the steering assist device 1 is operated, the obstacle detection circuit 34 detects the obstacle OB present on the travel route of the host vehicle V at every predetermined sampling time, for example, every 10 [msec] (step S300). ("Obstacle detection" shown in FIG. 4) (step S300). Then, the obstacle detection circuit 34 that has detected the obstacle OB outputs an information signal including the detected obstacle OB to the avoidance target point calculation circuit 36. When the obstacle OB is detected in step S300, the process performed by the steering assist device 1 proceeds to step S302.

In step S302, the avoidance target point calculation circuit 36 calculates the avoidance target point P _t (shown in step S302 "target point P _t calculated"). The avoidance target point calculating circuit to calculate the avoidance target point P _t 36, the information signal including the calculated avoidance target point P _t, and outputs a direction angle calculating circuit 38. When the avoidance target point P _t is calculated in step S302, the process performed by the steering assist device 1 proceeds to the process of step S304.

In step S304, the directional angle calculating circuit 38, with respect to the traveling direction of the host vehicle V, calculates a direction difference angle β of avoidance target point P _t (shown in step S304, "Direction angle calculation"). Then, the direction angle calculation circuit 38 that has calculated the difference direction angle β outputs an information signal including the calculated difference direction angle β to the torque command value calculation device 10. When the difference direction angle β is calculated in step S304, the process performed by the steering assist device 1 proceeds to step S306.

In step S306, the torque command value calculation device 10 calculates a torque command value _To3 that is a command value of the steering assist torque amount output to the electric motor 30 ("torque command value _To3 calculation" shown in step S306). Then, the torque command value calculating unit 10 which calculates the torque command value T _o3 is an information signal including the torque command value T _o3 calculated, and outputs the torque command damping circuit 12. When the torque command value _To3 is calculated in step S306, the process performed by the steering assist device 1 proceeds to step S308.

In step S308, the torque command attenuation circuit 12 determines whether or not the difference direction angle β calculated by the direction angle calculation circuit 38 is less than the difference direction angle coefficient ψ (“direction angle <ψ?” Shown in step S308). To do.
If it is determined in step S308 that the difference direction angle β calculated by the direction angle calculation circuit 38 is greater than or equal to the difference direction angle coefficient ψ (“NO” shown in the drawing), the processing performed by the steering assist device 1 is performed in step S310. Migrate to

On the other hand, if it is determined in step S308 that the difference direction angle β calculated by the direction angle calculation circuit 38 is less than the difference direction angle coefficient ψ (“YES” shown in the figure), the processing performed by the steering assist device 1 is performed in step S308. The process proceeds to S312.
At step S310, the the torque command attenuating circuit 12 to generate a torque attenuation command value T _3, including a command signal to be output to the electric motor 30, a command signal including a torque attenuation command value T ₃ that this product, to the electric motor 30 Output.

Here, the torque attenuation command value T ₃ is generated using the above-described equation (17) (“T ₃ = T _o3 ” shown in step S310).
In step S310, the and outputs a command signal including a torque attenuation command value T ₃ to the electric motor 30, process steering assist device 1 performs, the process proceeds to step S322.
In step S312, the torque command attenuation circuit 12, from the information signal input from the steering angular velocity sensor 8, steering angular velocity theta _'3 detection (shown in step S312 "steering angular velocity detection"). When the steering angular velocity θ ′ ₃ is detected in step S312, the process performed by the steering assist device 1 proceeds to step S314.

In step S314, the traveling direction of the host vehicle V performing a turning motion to avoid the obstacle OB has passed the point (zero point) where the difference direction angle β is “0” by the torque command attenuation circuit 12. (“Is the zero point passed?” Shown in step S314).
In step S314, the determines that the traveling direction of the host vehicle V has not passed the avoidance target point P _t (shown in FIG. "NO"), the process of steering assist device 1 performs, the process proceeds to step S316.

On the other hand, in step S314, the determines that the traveling direction of the host vehicle V has passed the avoidance target point P _t (shown in FIG. "YES"), the process of steering assist device 1 performs, the process proceeds to step S320.
In step S316, the torque command attenuation circuit 12 calculates the target damping torque T _a3 (shown in step S316 "damping torque T _a3 calculation"). When the target damping torque _Ta3 is calculated in step S316, the processing performed by the steering assist device 1 proceeds to step S318.

In step S318, the torque command attenuating circuit 12 to generate a torque attenuation command value T _3, including a command signal to be output to the electric motor 30, a command signal including a torque attenuation command value T ₃ that this product, to the electric motor 30 Output.
Here, the torque attenuation command value T ₃ is generated using the above-described equation (19) (“T ₃ = T _o3 + T _a3 ” shown in step S318).
In step S318, and outputs a command signal including a torque attenuation command value T ₃ to the electric motor 30, process steering assist device 1 performs, the process proceeds to step S322.

In step S320, the torque command attenuating circuit 12 to generate a torque attenuation command value T _3, including a command signal to be output to the electric motor 30, a command signal including a torque attenuation command value T ₃ that this product, to the electric motor 30 Output.
Here, the torque attenuation command value T ₃ is generated using the above-described equation (20) (“T ₃ = T _o3 + T _max3 ” shown in step S320).
In step S320, and outputs a command signal including a torque attenuation command value T ₃ to the electric motor 30, process steering assist device 1 performs, the process proceeds to step S322.

In step S <b> 322, a current controlled based on the command signal input from the torque command attenuation circuit 12 is supplied to the electric motor 30. Thus, in step S322, as the steering assist torque corresponding to the torque damping command value T ₃ the torque command attenuator 12 was generated is output to the steering wheel, controls the electric motor 30 (shown in step S322, "the electric motor Control ").
At this time, when the processing performed by the steering assist device 1 shifts from step S310 to step S322 described above, the torque command value _To3 is not attenuated, so the steering assist torque output to the steering wheel is the torque command value T _The steering assist torque is equivalent to _o3 .

When the steering assist torque output to the steering wheel becomes a steering assist torque corresponding to the torque command value _To3 , the maximum steering assist torque is provided to the driver of the host vehicle via the steering wheel. Therefore, even if the current travel route of the host vehicle is away from the target travel route and the host vehicle is likely to deviate from the travel lane, it is possible to reduce the burden of the steering operation. The host vehicle can be positioned in the travel lane.

Further, when the processing performed by the steering assist device 1 shifts from step S318 to step S322 described above, the degree of attenuation of the torque command value _To3 is greater than the minimum value, and thus the steering assist torque output to the steering wheel. Is smaller than the maximum value.
When the steering assist torque output to the steering wheel is smaller than the maximum value, the driver of the host vehicle is provided with a steering assist torque smaller than the maximum value via the steering wheel. For this reason, an appropriate steering assist torque is provided to bring the current travel route of the host vehicle closer to the target travel route, and the burden of the steering operation can be reduced, and the host vehicle is placed in the travel lane. It becomes possible to position.

Further, when the processing performed by the steering assist device 1 shifts from step S320 described above to step S322, the degree of attenuation of the torque command value _To3 is maximized, so the steering assist torque output to the steering wheel is the minimum value. It becomes.
When the steering assist torque output to the steering wheel becomes a minimum value, a small steering assist torque is provided to the driver of the host vehicle via the steering wheel. For this reason, after the current travel route of the host vehicle is set as the target travel route, a steering assist torque that can suppress the travel route of the host vehicle from moving away from the target travel route is provided, and the steering operation load is reduced. It becomes possible to reduce.
And controls the electric motor 30 in step S322, the steering assist torque corresponding to the torque damping command value T ₃ in which the torque command attenuator 12 is generated, and outputs to the steering wheel, the process of steering assist device 1 performs, in step S300 Return to processing.

  As described above, the combination of the laser sensor 32 obstacle detection circuit 34 and the avoidance target point calculation circuit 36 forms a combination of the above-described current state detection means and target state provision means. Similarly, the direction angle calculation circuit 38 forms the above-described state deviation degree calculation means, and the steering angular velocity sensor 8 forms the above-described steering angular velocity detection means. The torque command value calculation device 10 forms the steering assist torque calculation means described above, the torque command attenuation circuit 12 forms the steering assist torque attenuation means described above, and the electric motor 30 includes the steering characteristic control means described above. Is forming.

(Effect of the third embodiment)
(1) In this embodiment, the target state is the target direction angle, the current state is the current direction angle, and the state divergence is the difference between the target direction angle and the current direction angle.
For this reason, it is possible to provide the driver of the host vehicle with a steering assist device that can quickly correct the deviation of the current host vehicle traveling direction from the target traveling direction.
As a result, it is possible to provide the driver of the host vehicle with a steering assist device that is less uncomfortable for the driver of the host vehicle even in a situation where a quick and reliable steering operation is required.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. In addition, description may be abbreviate | omitted about the structure similar to 1st embodiment mentioned above.
(Constitution)
FIG. 12 is a block diagram illustrating a configuration of the steering assist device 1 of the present embodiment.
As shown in FIG. 12, the steering assist device 1 of this embodiment includes a target steering angle calculation device 2, a steering angle sensor 4, a steering angle deviation calculation circuit 6, a torque command value calculation device 10, and calculation accuracy. An estimation unit 40, a torque command attenuation circuit 12, and an EPS 14 are provided.
The configurations of the target steering angle calculation device 2, the steering angle sensor 4, the steering angle deviation calculation circuit 6, the torque command value calculation device 10 and the EPS 14 are the same as those in the first embodiment described above. Omitted.

The calculation accuracy estimation unit 40 estimates the calculation accuracy of the state deviation degree based on the information signal input from the steering angle deviation calculation circuit 6, and outputs an information signal including the estimated calculation accuracy to the torque command attenuation circuit 12. To do.
Here, the calculation accuracy is estimated according to, for example, an environment in which a sensor such as a CCD camera included in the imaging circuit 16 is used, or a change in sensor performance. Specifically, it is estimated that the calculation accuracy decreases as the environment in which the sensor is used is worse, such as at night, in rainy weather, or in dense fog. In addition to this, when the detection accuracy of the sensor is reduced, such as when dirt is attached to the detection unit of the sensor, it is estimated that the calculation accuracy is reduced.

The torque command attenuation circuit 12 calculates an attenuation command signal for attenuating the torque command value _To1 calculated by the torque command value calculation device 10 based on the information signals input from the torque command value calculation device 10 and the calculation accuracy estimation unit 40. To do. Then, by generating a torque attenuation command value obtained by attenuating the torque command value T _o1 by the calculated attenuation command signal, and outputs it to EPS14.

Here, the torque command attenuation circuit 12 performs the processing described below when calculating the attenuation command signal.
Specifically, the torque attenuation command value T ₁ is generated with reference to the calculation accuracy estimated by the calculation accuracy estimation unit 40. Then, the torque command attenuation circuit 12 which generates a torque attenuation command value T ₁ is a command signal including a torque attenuation command value T ₁ that the generated outputs to EPS14.

Hereinafter, the relationship between the calculation accuracy estimated by the calculation accuracy estimation unit 40 and the torque attenuation command value T ₁ will be described.
When receiving the input of the information signal from the calculation accuracy estimation unit 40, the torque command attenuation circuit 12 refers to the calculation accuracy included in the input information signal. For example, when the calculation accuracy estimated by the calculation accuracy estimation unit 40 is low using the map shown in FIG. 13, the coefficient of the damping torque is decreased as compared with the case where the calculation accuracy estimated by the calculation accuracy estimation unit 40 is high. . FIG. 13 is an explanatory diagram for explaining the output rule of the torque command value output via the torque command attenuation circuit.
Thus, the steering assist torque attenuation means 12 causes the degree of attenuation of the steering assist torque to increase when the calculation accuracy estimated by the calculation accuracy estimation unit 40 is low than when the calculation accuracy estimated by the calculation accuracy estimation unit 40 is high. Then, an attenuation command signal is calculated.

(Operation)
Next, an example of an operation performed by the steering assist device 1 of the present embodiment will be described with reference to FIGS. 12 and 13 and FIG.
FIG. 14 is a flowchart showing processing performed by the steering assist device 1 of the present embodiment.
The flowchart shown in FIG. 14 starts from a state in which the host vehicle is running and the driver for operating the steering assist device 1 is operated (ON) by the driver of the host vehicle (“START” shown in FIG. 14). ").

Since the process from step S400 to S406 is the same as the process from step S100 to S106 of the first embodiment described above, the description thereof is omitted. When the torque command value _To1 is calculated in step S406, the process performed by the steering assist device 1 proceeds to step S408.

In step S408, the torque command attenuation circuit 12, generates a torque attenuation command value T ₁ ( "in accordance with the calculation accuracy generating a torque attenuation command value T _1" in step S408) to. Then, the torque command attenuation circuit 12 which generates a torque attenuation command value T ₁ is a command signal including a torque attenuation command value T ₁ that generated, and outputs it to EPS14. In step S408, and outputs a command signal including a torque attenuation command value T ₁ to EPS14, processing steering assist device 1 performs, the process proceeds to step S410.

In step S410, the current supplied to the electric motor is controlled based on the command signal input from the torque command attenuation circuit 12 in EPS14. Thus, in step S410, as the steering assist torque is a torque command attenuation circuit 12 corresponds to the torque damping command value T ₁ generated is outputted to the steering wheel, "controls the EPS" shown in the control (step S410 the EPS14 )
Controls EPS14 In step S410, the steering assist torque corresponding to the torque damping command value T ₁ which torque command attenuator 12 is generated, and outputs to the steering wheel, processing the steering assistance apparatus 1 performs the processing of step S400 Return.

  As described above, the target steering angle calculation device 2 forms the above-described target state providing unit, the steering angle sensor 4 forms the above-described current state detection unit, and the steering angle deviation calculation circuit 6 performs the above-described state divergence degree. A calculation means is formed. Further, the steering angular velocity sensor 8 forms the steering angular velocity detection means described above, and the torque command value calculation device 10 forms the steering assist torque calculation means described above. Further, the torque command attenuation circuit 12 forms the steering assist torque attenuation means described above, and the EPS 14 forms the steering characteristic control means described above.

(Effect of the fourth embodiment)
(1) In the present embodiment, when the calculation accuracy estimated by the calculation accuracy estimation unit is low, the steering assist torque attenuation means has a degree of attenuation of the steering support torque higher than that when the calculation accuracy estimated by the calculation accuracy estimation unit is high. An attenuation command signal is calculated so as to increase.
For this reason, when the calculation accuracy is low, it is possible to perform control without impeding prompt steering for the driver of the host vehicle, compared to when the calculation accuracy is high.
As a result, it is possible to reflect the driver's intention even in situations where a quick and reliable steering operation is required. Therefore, a steering assist device that is less uncomfortable for the driver of the host vehicle can be operated. Can be provided to a person.

(Modification)
(1) In the steering assist device 1 of the present embodiment, the state divergence degree calculation means is formed by the steering angle deviation calculation circuit 6, but the present invention is not limited to this. That is, the state deviation degree calculating means may be formed by the lateral position deviation calculating circuit 28. Similarly, the state divergence calculating means may be formed by the direction angle calculating circuit 38. Further, the state divergence calculating means may have at least two of the steering angle deviation calculating circuit 6, the lateral position deviation calculating circuit 28, and the direction angle calculating circuit 38.

DESCRIPTION OF SYMBOLS 1 Steering assistance apparatus 2 Target steering angle calculation apparatus 4 Steering angle sensor 6 Steering angle deviation calculation circuit 8 Steering angular velocity sensor 10 Torque command value calculation apparatus 12 Torque command attenuation circuit 14 EPS
DESCRIPTION OF SYMBOLS 16 Image pick-up circuit 18 Image processing circuit 20 Target path | route calculation circuit 22 Target steering angle calculation circuit 24 Magnetic sensor 26 Target path | route detection circuit 28 Lateral position deviation calculation circuit 30 Electric motor 32 Laser sensor 34 Obstacle detection circuit 36 Avoidance target point calculation circuit 38 Direction angle calculation circuit 40 Calculation accuracy estimation part V Own vehicle OB Obstacle

Claims (7)

A target state providing means for providing a target state of the host vehicle;
Current state detection means for detecting a current state of the current vehicle;
State divergence degree calculating means for calculating a state divergence degree that is a degree of divergence between the provided target state and the detected current state;
Steering assist torque calculating means for calculating a steering assist torque for reducing the calculated state deviation degree;
Steering characteristic control means for outputting the calculated steering assist torque to a steering wheel of the host vehicle;
Steering assist torque attenuation means for calculating an attenuation command signal for attenuating the calculated steering assist torque and attenuating the steering assist torque by the calculated attenuation command signal;
The target state providing means includes an imaging circuit that acquires an image of the traveling direction of the host vehicle, a target route calculation circuit that calculates a target route that the host vehicle should follow from the acquired image, and the calculated target route. A target steering angle calculation circuit for calculating a target steering angle;
A calculation accuracy estimator that estimates the calculation accuracy of the state divergence degree by the state divergence degree calculating means ,
The steering assist torque attenuating means has a state in which the degree of attenuation of the steering assist torque is larger than a preset degree of attenuation in a state where the calculated state divergence tends to decrease, and the calculated state divergence tends to increase Then, the attenuation command signal is calculated so that the degree of attenuation of the steering assist torque is less than or equal to a preset degree of attenuation . When the estimated calculation accuracy is low , the steering assist torque is higher than when the estimated calculation accuracy is high. A steering assist device for a vehicle , wherein the attenuation command signal is calculated so that a degree of torque attenuation increases . The target state provided by the target state providing means is a target steering angle that is a target rotation angle of the steering wheel,
The current state detected by the current state detection means is a current steering angle that is a current rotation angle of the steering wheel,
The state divergence calculated by the state divergence calculating means is a difference between the target steering angle provided by the target state providing means and the current steering angle detected by the current state detecting means. The vehicle steering assist device according to claim 1. The target state provided by the target state providing means is a target travel route that is a travel route targeted by the host vehicle,
The current state detected by the current state detection means is a relative position on the current travel route of the host vehicle with respect to the target travel route,
The state deviation degree calculated by the state deviation degree calculating means is a distance from the relative position detected by the current state detection means to the target travel route provided by the target state providing means. Item 2. A steering assist device for a vehicle according to Item 1. The target state provided by the target state providing means is a target direction angle that is an angle to a travel route targeted by the host vehicle with respect to a direction in which the host vehicle has traveled,
The current state detected by the current state detection means is a current direction angle that is a current angle of the host vehicle with respect to a direction in which the host vehicle is traveling,
The state divergence calculated by the state divergence calculating means is a difference between the target direction angle provided by the target state providing means and the current direction angle detected by the current state detecting means. The vehicle steering assist device according to claim 1. A steering angular velocity detecting means for detecting a current rotational angular velocity of the steering wheel as a steering angular velocity;
The steering assist torque attenuating unit calculates the attenuation command signal so that the degree of attenuation of the steering assist torque changes according to the steering angular velocity detected by the steering angular velocity detecting unit. To 4. The vehicle steering assist device according to any one of items 1 to 4.   The steering assist torque attenuating unit adds a coefficient set in advance to the steering angular velocity detected by the steering angular velocity detecting unit, and when the state divergence degree calculated by the state divergence degree calculating unit becomes zero. 6. The vehicle steering assist device according to claim 5, wherein the attenuation command signal is calculated so that the degree of attenuation of the steering assist torque is maximized. Obtaining an image of the traveling direction of the host vehicle, calculating a target route that the host vehicle should follow from the acquired image, and calculating a target steering angle from the calculated target route. Calculating a state deviation degree that is a deviation degree between the state and the current state of the host vehicle;
Estimating the calculation accuracy of the calculated state deviation degree,
When calculating the steering assist torque for reducing the calculated state divergence degree and outputting the calculated steering assistance torque to the steering wheel of the host vehicle, the calculated state divergence degree tends to be reduced. In a state, the degree of attenuation of the steering assist torque is greater than a preset degree of attenuation, and in a state where the calculated state deviation degree tends to expand, the degree of attenuation of the steering assist torque is equal to or less than the preset degree of attenuation. The attenuation command signal for attenuating the steering assist torque is calculated , and when the estimated calculation accuracy is low, the attenuation degree of the steering assist torque is increased so that the degree of attenuation of the steering assist torque is increased compared to the case where the estimated calculation accuracy is high A method for assisting steering of a vehicle, comprising calculating a command signal .

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