JP2013091370A - Steering support device and steering support method of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering support device and a steering support method of a vehicle capable of suppressing a degradation in reflection degree of driver's intention on steering operation.SOLUTION: A target steering angle, being a target rotation angle of a steering wheel of the own vehicle, is calculated. A current steering angle, being a current rotation angle of the steering wheel, is detected. A steering angle deviation, which is a difference between the target steering angle and the current steering angle, is calculated. A steering support torque for reducing the steering angle deviation is calculated. On a travelling road on which the own vehicle travels, an allowance, which is a distance between an obstacle present at least on either right or left side of the own vehicle in the width direction, and the own vehicle, is calculated at the time when the own vehicle reaches a target point, being a point on a target route which the own vehicle is expected to pass in the state that the rotation angle of the steering wheel is the target steering angle. The steering support torque, which is calculated to be smaller as the calculated allowance is larger, is output to the steering wheel.

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 steered wheel (steered wheel) for the purpose of traveling an optimal travel route for the host vehicle. An example of such a steering assist device is described in Patent Document 1.
The steering assist device described in Patent Literature 1 sets the possibility of contact with an obstacle that is predicted now and in the future by considering the relative motion between the obstacle and the host vehicle. This is a technique for the host vehicle to travel on a travel route that is optimal for avoiding the vehicle. Here, in order for the host vehicle to travel on the travel route optimal for avoiding the obstacle, steering control is performed to output torque to the steered wheels.

JP 2008-307951 A

  However, in the steering assist device described in Patent Document 1, an optimal travel route for avoiding an obstacle is set without considering the allowance between the obstacle and the host vehicle, and the set travel route is set as the host vehicle. Is output to the steering wheel. The margin is the distance between the obstacle and the host vehicle when the host vehicle reaches the target point on the travel route.

For this reason, when the travel route intended by the driver is a route deviating from the travel route set by the steering assist device, the travel route set by the steering assist device is used even when the margin is large. Steering support torque that causes the vehicle to travel is output to the steered wheels. Therefore, there is a possibility that a problem that the degree of reflection of the driver's intention with respect to the steering operation is lowered may occur. The situation where the allowance is large is, for example, a situation where the possibility that the host vehicle is in contact with an obstacle on the travel path is low.
The present invention has been made paying attention to the above-described problems, and provides a vehicle steering assistance device and a steering assistance method capable of suppressing a reduction in the degree of reflection of a driver's intention with respect to a steering operation. This is the issue.

  In order to solve the above-described problem, according to one aspect of the present invention, an obstacle that is present on at least one of the right side in the vehicle width direction and the left side in the vehicle width direction of the own vehicle is detected on a travel path on which the own vehicle runs. Furthermore, the obstacle and the host vehicle at the time when the host vehicle reaches a target point that is a point on the target route where the host vehicle is predicted to pass with the rotation angle of the steered wheel set as the target steering angle on the traveling road. The margin that is the distance between is calculated. Then, the steering assist torque is calculated to be smaller as the calculated margin is larger. Here, the steering assist torque is used to reduce a steering angle deviation that is a difference between a target steering angle that is a target rotation angle of the steering wheel of the host vehicle and a current steering angle that is a current rotation angle of the steering wheel. The torque output to the steered wheels.

  According to the present invention, when the travel route intended by the driver is a route deviating from the set travel route, the steering assist torque is increased with respect to the steering torque with which the driver steers the steered wheels as the margin is larger. The rate of interference will decrease. For this reason, even when the driving route intended by the driver is a route deviating from the set driving route, the degree of reflection of the driver's intention with respect to the steering operation is reduced according to the size of the margin. Can be suppressed.

It is a block diagram which shows the structure of the steering assistance apparatus of 1st embodiment of this invention. It is a figure which shows the relationship between an obstruction and the own vehicle. It is a figure which shows the relationship between a spring coefficient and a margin. It is a flowchart which shows the process which the steering assistance apparatus of 1st embodiment of this invention performs. It is a figure which shows the relationship between an obstruction and the own vehicle. It is a flowchart which shows the process which the steering assistance apparatus of the modification of this invention performs.

Embodiments of the present invention will be described below with reference to the drawings.
(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 margin allowance calculation unit 6, a steering angle deviation calculation unit 8, and a steering assist torque. The calculator 10, the steering angular velocity sensor 12, the torque command attenuation circuit 14, and the EPS 16 are provided.
The target steering angle calculation device 2 includes an imaging circuit 18, an image processing circuit 20, a target route calculation circuit 22, and a target steering angle calculation circuit 24.

The imaging circuit 18 includes an imaging unit such as a CCD camera, 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 18 outputs an information signal including the acquired image to the image processing circuit 20.
The image processing circuit 20 performs edge detection and the like on the image acquired by the imaging circuit 18 based on the information signal output from the imaging circuit 18, and further recognizes the object, so that the host vehicle can travel on the road. Detecting a special area. Then, the image processing circuit 20 outputs an information signal including the detected area to the target route calculation circuit 22 and the margin allowance calculation unit 6.

Here, the object to be recognized is specifically a white line (lane division line) on the road indicating the boundary of the driving lane, a side wall of the driving road, a guardrail, an obstacle or other vehicle on the road (on the driving road), walking Etc. 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 22 calculates a target route (traveling route) that the host vehicle should follow (travel) in the region detected by the image processing circuit 20 based on the information signal output from the image processing circuit 20. Then, the target route calculation circuit 22 outputs an information signal including the calculated target route to the target steering angle calculation circuit 24 and the margin allowance calculation unit 6.

  Specifically, when calculating the target route, first, the boundary between the region where the vehicle can travel and the other region (the boundary on the left side in the vehicle width direction) detected by the image processing circuit 20 is detected. And the right boundary in the vehicle width direction). 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. In addition, the area | region where the own vehicle can drive | work, and another area | region are areas which exist in the right and left of the own vehicle, respectively.

The target steering angle calculation circuit 24 is based on the information signal output from the target route calculation circuit 22 and the target rotation angle (steering operation amount) of the steering wheel from the target route calculated by the target route calculation circuit 22. A target steering angle is calculated. Then, the target steering angle calculation circuit 24 outputs an information signal including the calculated target steering angle to the steering angle deviation calculation unit 8. 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, on the travel route of the host vehicle, on the target route predicted to pass t seconds (for example, one second) after the current position of the host vehicle. Is set as the target point. That is, the target point is one of a plurality of points that form a travel route set by the steering assist device 1. The above “t seconds” is set in advance.
Next, the steering angle required to reach the set target point is calculated from the current position of the host vehicle on the travel road and the rotation angle of the steering wheel at the current position. The calculated steering angle is set as a target steering angle θ ^* .

The above “t seconds” may be set according to the vehicle speed. Further, when setting the target point, a point on the target route that is predicted to pass after t seconds from the current position is not set as the target point, and is t [m] ahead from the current position on the target route ( For example, a point 10 [m] ahead) may be set as the target point.
Here, in the present embodiment, as an example, a case where a vehicle motion model is stored in advance in the target steering angle calculation circuit 24 and this vehicle motion model is used for calculation of the target steering angle θ ^* will be described. Thereby, in the steering assist device 1 of the present embodiment, the target steering angle θ ^* can be calculated more accurately than in the case where the vehicle motion model is not used for the calculation of the target steering angle θ ^* .

The vehicle motion model is, for example, a model that indicates vehicle motion (yaw rate or the like) that occurs according to the steering angle and speed (vehicle speed) during traveling of the host vehicle, and is an individual parameter for the vehicle.
As described above, the target steering angle calculation device 2 calculates the target steering angle θ ^* and outputs an information signal including the calculated target steering angle θ ^* to the steering angle deviation calculation unit 8.

  The steering angle sensor 4 is provided, for example, in a steering column that rotatably supports the steering wheel. In addition, the steering angle sensor 4 detects a current steering angle that is a current rotation angle (steering operation amount) of the steering wheel by the driver. Then, the steering angle sensor 4 outputs an information signal including the detected current steering angle of the steered wheels to the steering angle deviation calculation unit 8. In the following description, the current steering angle may be described as “current steering angle θ”.

Here, recent vehicles often have a sensor that can detect the steering angle of the steered wheels as a standard. For this reason, in this embodiment, the case where the sensor which can detect the steering angle of the steering wheel which is an existing sensor in the own vehicle is used as the steering angle sensor 4 will be described.
The margin allowance calculation unit 6 sets, as a target point, a point on the target route that is predicted to pass after t seconds from the current position of the host vehicle on the traveling path of the host vehicle. Note that the setting of the target point is performed, for example, in the same procedure as the calculation of the target steering angle θ ^* described above.

  Then, as shown in FIG. 2, in the situation where the host vehicle V has reached the set target point, the right side distance dr between the obstacle B and the host vehicle V on the right side in the vehicle width direction of the host vehicle V, A left side distance dl between the obstacle B and the host vehicle V on the left side in the vehicle width direction is calculated. Then, an information signal including the calculated right distance dr and left distance dl is output to the steering assist torque calculation unit 10.

In addition, FIG. 2 is a figure which shows the relationship between an obstruction and the own vehicle. In FIG. 2, the host vehicle V at the current position is indicated by a symbol “Vs”, and the position of the host vehicle V after t seconds from the current position, that is, the position of the host vehicle V when reaching the set target point. And “Vt”.
In FIG. 2, as the obstacle B, two other vehicles (small vehicle B1 and large vehicle B2) existing on the road, and the side wall of the travel path (the side wall B3 on the right side in the vehicle width direction, the left side in the vehicle width direction) Side wall B4) is shown.

Here, the right distance dr and the left distance dl are the position of the host vehicle V in the state where the target point is reached and the obstacle existing in the vehicle width direction of the host vehicle V when the target point is reached. It calculates based on the distance with the object B.
That is, in this embodiment, the margin allowance calculation unit 6 uses the own vehicle V as the allowance that is the distance between the obstacle and the own vehicle when the own vehicle reaches the target point on the travel path of the own vehicle. The margin on the right side in the vehicle width direction and the margin on the left side in the vehicle width direction of the host vehicle are calculated.

The steering angle deviation calculation unit 8 calculates the steering angle deviation based on the information signal output from the target steering angle calculation device 2 and the steering angle sensor 4. Here, the steering angle deviation is a difference between the target steering angle θ ^* calculated by the target steering angle calculation device 2 and the current steering angle θ detected by the steering angle sensor 4. 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 unit 8 outputs an information signal including the calculated steering angle deviation δθ to the steering assist torque calculation unit 10.
The steering assist torque calculator 10 calculates a torque command signal based on the information signals output by the margin allowance calculator 6 and the steering angle deviation calculator 8. Then, the steering assist torque calculation unit 10 outputs an information signal including the calculated torque command signal to the torque command attenuation circuit 14.

Here, the torque command signal is a command value of the steering assist torque. Specifically, the torque command signal is a command value for reducing the steering angle deviation δθ calculated by the steering angle deviation calculation unit 8. In the following description, a torque command signal, may be referred to as "torque command value T _o."
Here, the steering assist torque calculating unit 10, when calculating the torque command value T _o, performs the processing described below.

Specifically, first, a short distance is selected from the above-described right distance dr and left distance dl with reference to the information signal output by the margin calculation unit 6. When the right distance dr and the left distance dl are the same value, either the right distance dr or the left distance dl is selected.
Then, the steering assist torque calculating unit 10, the longer the distance the selected (dr or dl), so that the torque command value T _o decreases, calculates the spring constant K (c) used for calculating the torque command value T _o To do.

Here, the spring coefficient K (c) is a coefficient of c = min (dr, dl), that is, a coefficient based on the minimum distance among the right distance dr and the left distance dl.
That is, the steering assist torque calculating unit 10, the torque command value T _o, shown in FIG. 3, is calculated using the relation between the allowance spring coefficient K (c), the formula (2) shown below. Here, the margin is a margin between the obstacle B and the host vehicle V. FIG. 3 is a diagram showing the relationship between the spring coefficient K (c) and the margin.

Accordingly, the steering assist torque calculating unit 10, the larger the margin between the obstacle B and the vehicle V, and calculates the torque command value T _o to a smaller value.
T _o = K (c) × (θ−θ ^* ) (2)
That is, the steering assist torque calculating unit 10, the larger the margin which margin calculating section 6 calculates, as the steering assist torque is reduced, and calculates the torque command value T _o.

Further, the steering assist torque calculating unit 10, a torque calculation time interval set in advance, it calculates the torque command value T _o. Here, the torque calculation time is set in advance as, for example, 50 [msec] or 100 [msec]. In the present embodiment, as an example, the steering assist torque calculating unit 10 is an interval of the torque calculation time for calculating the torque command value T _o, describing the case of setting the 100 [msec].

  As with the steering angle sensor 4, the steering angular velocity sensor 12 is provided, for example, in a steering column that rotatably supports the steering wheel. The steering angular velocity sensor 12 detects a steering angular velocity that is a rotational angular velocity at the time of the current steering of the steered wheels by the driver of the host vehicle. Then, the steering angular velocity sensor 12 outputs an information signal including the detected steering angular velocity to the torque command attenuation circuit 14. In the following description, the steering angular velocity may be described as “steering angular velocity θ ′”.

Here, recent vehicles often include a sensor that can detect the steering angular velocity of the steered wheels 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 which is an existing sensor in the own vehicle is used as the steering angular velocity sensor 12 will be described.
The torque command attenuation circuit 14 calculates an attenuation command signal based on the information signals output from the steering assist torque calculation unit 10 and the steering angular velocity sensor 12.

Here, the attenuation command signal is information signals including a command steering assist torque calculation unit 10 attenuates the torque command value T _o calculated. Then, the torque command attenuating circuit 14, an information signal including a torque attenuation command value obtained by attenuating the torque command value T _o by the calculated attenuation command signal, and outputs it to EPS16.
In the present embodiment, as an example, a case where the torque attenuation command value T is calculated using the following equation (3) will be described.
T = (θ−θ ^* ) × θ ′ + T _o (3)

Accordingly, the torque command attenuation circuit 14 of the present embodiment, in accordance with the steering angular velocity theta ', so that the attenuation degree of the torque command value T _o (torque command signal) changes, to calculate a torque damping command value T.
The torque command attenuation circuit 14 that has calculated the torque attenuation command value T outputs a command signal including the calculated torque attenuation command value T to the EPS 16.
The EPS 16 has an electric motor that can output a steering assist torque to the steered wheels. Therefore, the EPS 16 is formed by using, for example, a known electric power steering.

The EPS 16 controls the electric motor based on the command signal input from the torque command attenuation circuit 14. Thereby, the EPS 16 outputs a steering assist torque corresponding to the torque attenuation command value T calculated by the torque command attenuation circuit 14 to the steered wheels.
Note that the electric motor control performed by the EPS 16 is generally performed by controlling the current supplied to the electric motor. Therefore, also in the present 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 is output to the steered wheels.

Hereinafter, an example of the operation performed by the steering assist device 1 of the present embodiment will be described with reference to FIGS. 1 to 3 and FIG. 4.
FIG. 4 is a flowchart showing processing performed by the steering assist device 1 of the present embodiment.
The flowchart shown in FIG. 4 starts when the host vehicle V is running and the driver of the host vehicle V operates (ON) the switch that operates the steering assist device 1 (see “ START ").

When the steering assist device 1 is operated, the target steering angle calculation device 2 calculates the target steering angle θ ^* at every preset sampling time, for example, every 10 [msec] (“target steering angle shown in step S100”). Calculation ") (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 calculating section 8. 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 steered wheels to the steering angle deviation calculator 8. 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 unit 8 calculates a steering angle deviation δθ that is a 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 unit 8 that has calculated the steering angle deviation δθ outputs an information signal including the calculated steering angle deviation δθ to the steering assist torque calculation unit 10. 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 margin allowance calculation unit 6 calculates the right-side distance dr between the obstacle B and the host vehicle V on the right side in the vehicle width direction of the host vehicle V when the host vehicle V has reached the target point described above (step S106). "Calculate right side distance dr" shown in S106). Then, the margin calculation unit 6 that has calculated the right distance dr outputs an information signal including the calculated right distance dr to the steering assist torque calculation unit 10. When the right distance dr is calculated in step S106, the process performed by the steering assist device 1 proceeds to step S108.

  In step S108, the margin allowance calculation unit 6 calculates the left-side distance dl between the obstacle B and the host vehicle V on the right side in the vehicle width direction of the host vehicle V when the host vehicle V has reached the target point described above (step S108). "Calculate left distance dl" shown in S108). Then, the margin allowance calculation unit 6 that has calculated the left distance dl outputs an information signal including the calculated left distance dl to the steering assist torque calculation unit 10. When the left distance dl is calculated in step S108, the process performed by the steering assist device 1 proceeds to step S110.

Note that the process of step S106 and the process of step S108 may be performed in the reverse order (step S104 → step S108 → step S106 → step S110).
In step S110, the steering assist torque calculation unit 10 selects a short distance from the above-described right distance dr and left distance dl. Thus, in step S110, the steering assist torque calculation unit 10 determines a margin for use in calculating the torque attenuation command value T (“determination of margin allowance min (dr, dl)” shown in step S110). When the margin is determined in step S110, the process performed by the steering assist device 1 proceeds to step S112.

In step S112, the steering assist torque calculating unit 10, calculates the torque command value T _o (shown in step S112, "torque command value T _o calculation") to. Then, the steering assist torque calculating unit 10 which calculates the torque command value T _o is an information signal including the calculated torque command value T _o, and outputs the torque command damping circuit 14. In step S112, calculating the torque command value T _o, process steering assist device 1 performs, the process proceeds to step S114.

Here, when calculating the torque command value T _o is, the longer the determined distance (dr or dl) at step S110, so that the torque command value T _o decreases, the above-mentioned spring constant K a (c) Calculate.
In step S114, the steering angular velocity sensor 12 detects the steering angular velocity θ ′ (“steering angular velocity detection” shown in step S114). Then, the steering angular velocity sensor 12 that has detected the steering angular velocity θ ′ outputs an information signal including the detected steering angular velocity θ ′ to the torque command attenuation circuit 14. When the steering angular velocity θ ′ is detected in step S114, the processing performed by the steering assist device 1 proceeds to step S116.

In step S116, the torque command attenuation circuit 14 calculates the torque attenuation command value T included in the command signal output to the EPS 16 ("torque attenuation command value T calculation" shown in step S116). Then, the torque command attenuation circuit 14 that has calculated the torque attenuation command value T outputs a command signal including the calculated torque attenuation command value T to the EPS 16.
In step S116, when a command signal including the torque attenuation command value T is output to the EPS 16, the processing performed by the steering assist device 1 proceeds to step S118.

In step S118, the current supplied to the electric motor is controlled based on the command signal output from the torque command attenuation circuit 14 in EPS16. As a result, in step S122, the EPS 16 is controlled so as to output the steering assist torque corresponding to the torque attenuation command value T calculated by the torque command attenuation circuit 14 to the steered wheels ("EPS control" shown in step S118). .
Here, the steering assist torque calculation unit 10 as the margin of margin calculating section 6 calculates (right distance dr or left distance dl) is large, and calculates the steering assist torque (torque command value T _o) to a small value ing.

For this reason, when the travel route intended by the driver is a route deviating from the set travel route, the greater the margin is, the greater the margin is, the steering assist torque (torque) The rate at which the command value T _o ) interferes decreases.
As a result, when the travel route intended by the driver is a route deviating from the set travel route, the smaller the allowance is, the smaller the steering assist torque calculated is output to the steered wheels.

Here, “when the driving route intended by the driver is a route deviating from the set driving route” means that the point passing through the current position of the host vehicle after t seconds from the driving route intended by the driver. The case where it is the point which deviated from on the target path | route mentioned above is shown. Specifically, in FIG. 2, the position of the host vehicle V traveling between the small vehicle B1 and the side wall B3 is a position closer to the small vehicle B1 than the position Vt or a position closer to the side wall B3. This is the case.
When the EPS 16 is controlled in step S118 and the steering assist torque corresponding to the torque attenuation command value T calculated by the torque command attenuation circuit 14 is output to the steered wheels, the processing performed by the steering assist device 1 returns to the processing in step S100. ("RETURN" shown in FIG. 5).

(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.
As described above, when the driver operates the steering assist device 1 during traveling of the host vehicle V, the steering assist device 1 calculates the target steering angle θ ^* , detects the current steering angle θ, and determines the steering angle deviation δθ. Perform the calculation. Then, for example, in a situation where the host vehicle V travels between the small vehicle B1 and the side wall B3 (see FIG. 2), the steering assist device 1 calculates the right distance dr and the left distance dl.

After calculating the right side distance dr and the left side distance dl, the steering assist torque calculation unit 10 selects a short distance from the above-described right side distance dr and left side distance dl and uses it to calculate the torque attenuation command value T. Determine margins.
Steering assist torque calculation unit 10 determining the margin calculates the torque command value T _o, the information signal including the calculated torque command value T _o, and outputs the torque command damping circuit 14.
Further, the steering angular velocity sensor 12 detects the steering angular velocity θ ′, and outputs an information signal including the detected steering angular velocity θ ′ to the torque command attenuation circuit 14.

Upon receiving information signals from the steering assist torque calculation unit 10 and the steering angular velocity sensor 12, the torque command attenuation circuit 14 calculates a torque attenuation command value T, and sends a command signal including the calculated torque attenuation command value T to the EPS16. Output to.
Receiving the command signal, the EPS 16 controls the EPS 16 so that the steering assist torque corresponding to the torque attenuation command value T calculated by the torque command attenuation circuit 14 is output to the steered wheels. As a result, the steering assist torque interferes with the steering torque with which the driver steers the steered wheels.

At this time, when the travel route intended by the driver is a route deviating from the set travel route, the smaller the allowance is, the smaller the steering assist torque calculated is output to the steered wheels.
For this reason, for example, when the space between the small vehicle B1 and the side wall B3 is wide, the rate at which the steering assist torque interferes with the steering torque is lower than when the space between the small vehicle B1 and the side wall B3 is narrow. To do.
Thereby, even if the travel route intended by the driver is a route deviating from the set travel route, the degree of reflection of the driver's intention with respect to the steering operation is changed according to the margin allowance. It becomes possible.

  As described above, the steering support method implemented by the operation of the steering support device 1 of the present embodiment includes the steering angle deviation calculating step for calculating the steering angle deviation, and the steering support torque for reducing the steering angle deviation. A steering assist torque calculating step for calculating; In addition, the steering support method includes a steering support torque output step for outputting the steering support torque to the steered wheels, and a margin allowance calculation step for calculating a margin allowance. In the steering assist torque calculating step, the steering assist torque is calculated to be smaller as the allowance calculated in the allowance calculating step is larger.

As described above, the target steering angle calculation device 2 corresponds to the target steering angle calculation unit, the travel path detection unit, and the obstacle detection unit. The steering angle sensor 4 corresponds to the current steering angle detection unit. EPS 16 corresponds to a steering assist torque output unit. The torque command attenuation circuit 14 corresponds to a steering assist torque attenuation unit.
Similarly, step S104 corresponds to a steering angle deviation calculating step. Steps S106 to S110 correspond to a margin calculation step. Step S112 corresponds to a steering assist torque calculating step. Step S118 corresponds to a steering assist torque output step.

(Effects of the first embodiment)
(1) steering assist torque calculating section 10, the larger the margin which margin calculating section 6 calculates, calculated steering assist torque (torque command value T _o) to a small value.
For this reason, when the travel route intended by the driver is a route deviating from the set travel route, the larger the allowance calculated by the allowance calculating unit 6 is, the greater the steering torque with which the driver steers the steered wheels is. As a result, the rate at which the steering assist torque interferes decreases.
As a result, even if the travel route intended by the driver is a route deviating from the set travel route, the driver's steering operation is performed according to the margin allowance calculated by the allowance allowance calculation unit 6. It is possible to suppress a decrease in the degree of reflection of intention.

(2) The margin allowance calculation unit 6 calculates a right side distance dr (a margin margin on the right side in the vehicle width direction of the host vehicle V) and a left side distance dl (a margin margin on the left side in the vehicle width direction of the host vehicle V). In addition to this, the steering assist torque calculator 10 calculates the steering assist torque using a short distance (small margin) of the right distance dr and the left distance dl calculated by the margin allowance calculator 6.
As a result, even when the overall allowance is large, in the situation where the host vehicle V has a tendency to approach obstacles such as side walls, the possibility of contact / arrival with obstacles increases. It can be transmitted to the driver by a change in the magnitude of the steering assist torque.

(3) The steering assist torque calculating unit 10 calculates the steering assist torque at a preset torque calculation time interval (for example, 50 [msec] interval, 100 [msec] interval).
As a result, it is possible to transmit a change in the situation that changes with time (for example, a change in the margin allowance) to the driver by a change in the magnitude of the steering assist torque.

(4) In the steering assist method of the present embodiment, the steering assist torque is calculated to be a smaller value in step S112 as the allowance calculated in steps S106 to S110 is larger.
For this reason, when the travel route intended by the driver is a route deviating from the set travel route, the larger the allowance calculated by the allowance calculating unit 6 is, the greater the steering torque with which the driver steers the steered wheels is. As a result, the rate at which the steering assist torque interferes decreases.
As a result, even if the travel route intended by the driver is a route deviating from the set travel route, the driver's steering operation is performed according to the margin allowance calculated by the allowance allowance calculation unit 6. It is possible to suppress a decrease in the degree of reflection of intention.

(Modification)
(1) In the steering assist device 1 of the present embodiment, the configuration of the margin allowance calculation unit 6 is configured to calculate the right side distance dr and the left side distance dl as a margin, but the configuration of the margin allowance calculation unit 6 is However, the present invention is not limited to this.
That is, for example, the configuration of the steering assist device 1 is arranged on the front surface of the host vehicle V in the vehicle front-rear direction, and includes a plurality of laser sensors that irradiate the front of the host vehicle V with respect to the vehicle front-rear direction. To do. Then, by using a plurality of laser sensors, the laser irradiation and the laser reflected by the obstacle on the travel route after the laser irradiation are received, the time when the laser was irradiated and received, and the direction in which the laser was received. Is output to the margin calculation unit 6.

  Thus, for example, as shown in FIG. 5, a plurality of lasers are irradiated from the traveling direction to the vehicle width direction within a predetermined irradiation range with respect to the traveling direction of the host vehicle V (front in the vehicle front-rear direction). Receive the irradiated laser. Based on the time when the laser is irradiated and received and the direction in which the laser is received, the margin is calculated using the following equations (4) to (7). In addition, FIG. 5 is a figure which shows the relationship between an obstruction and the own vehicle.

  In the above equation (4), “v” is the vehicle speed of the host vehicle V. Further, in the above equation (4), “di” is, as shown in FIG. 5, the own vehicle V when the laser irradiated by the i-th laser sensor among the plurality of laser sensors is reflected on the wall B3. And the distance between the wall B3. Further, in the above equation (4), “θi” is, as shown in FIG. 5, the angle closer to the host vehicle V among the angles formed by the laser irradiated by the i-th laser sensor and the wall B3 in a top view. Is an angle.

In the above equation (5), “φi” is an angle formed by the traveling direction of the host vehicle V and the laser irradiated by the i-th laser sensor in a top view.
In addition, as shown in FIG. 5, “C _right ” calculated by the above equation (6) has a wall B3 that is an obstacle B on the right side in the vehicle width direction of the host vehicle V, and the wall B3 is i-th. This is the allowance between the obstacle B and the host vehicle V when the laser emitted by the laser sensor is reflected. In the following description, the margin C _right may be described as “Cr”.

“C _left ” calculated by the above equation (7) is not particularly shown, but an obstacle B such as a wall exists on the left side in the vehicle width direction of the host vehicle V, and the i-th laser sensor is located on this obstacle B. Is a margin for the obstacle B and the host vehicle V when the laser irradiated by is reflected. In the following description, the margin C _left may be described as “Cl”.
Note that the preset irradiation range is, for example, 60 [°] on the left and right with reference to an axis extending from the center in the vehicle width direction of the host vehicle V toward the front in the vehicle front-rear direction and orthogonal to the vehicle width direction. To do.

An example of the operation performed by the steering assist device 1 having such a configuration will be described below with reference to FIGS. 1 to 5 and FIG. FIG. 6 is a flowchart illustrating processing performed by the steering assist device 1 according to the modification.
The flowchart shown in FIG. 6 starts from a state in which the host vehicle V is traveling and a switch for operating the steering assist device 1 is operated (ON) by the driver of the host vehicle V (shown in FIG. 6). “START”).

In addition, since the process of step S200-S204 is the same as the process of step S100-S104 mentioned above, the description is abbreviate | omitted. When the steering angle deviation δθ is calculated in step S204, the processing performed by the steering assist device 1 proceeds to step S206.
In step S206, the margin allowance calculation unit 6 calculates a margin allowance Cr between the obstacle B and the subject vehicle V on the right side in the vehicle width direction of the host vehicle V ("calculation of right margin allowance Cr" shown in step S206). Then, the margin allowance calculation unit 6 that calculated the right margin allowance Cr outputs an information signal including the calculated right margin allowance Cr to the steering assist torque calculation unit 10. When the right margin allowance Cr is calculated in step S206, the processing performed by the steering assist device 1 proceeds to step S208.

In step S208, the margin allowance calculation unit 6 calculates a margin allowance Cl between the obstacle B and the host vehicle V on the left side in the vehicle width direction of the host vehicle V ("calculation of left margin allowance Cl" shown in step S208). Then, the margin allowance calculation unit 6 that has calculated the left margin allowance Cl outputs an information signal including the calculated left margin allowance Cl to the steering assist torque calculation unit 10. When the left margin Cl is calculated in step S208, the process performed by the steering assist device 1 proceeds to step S210.
Note that the process of step S206 and the process of step S208 may be performed in the reverse order (step S204 → step S208 → step S206 → step S210).

In step S210, the steering assist torque calculation unit 10 selects a large margin between the right margin margin Cr and the left margin margin Cl described above. As a result, in step S210, the steering assist torque calculation unit 10 determines an allowance used for calculating the torque attenuation command value T (“determination of allowance max (Cr, Cl)” shown in step S210). When the margin is determined in step S210, the process performed by the steering assist device 1 proceeds to step S212.
Since the process of step S212-S218 is the same as the process of step S112-S118 mentioned above, the description is abbreviate | omitted.

(2) In the steering assist device 1 of the present embodiment, the steering assist torque calculation unit 10 calculates the steering assist torque at a preset torque calculation time interval, but the present invention is not limited to this. That is, for example, the steering assist torque calculation unit 10 may continuously calculate the steering assist torque while the host vehicle V is traveling.

(3) In the steering assist device 1 of the present embodiment, as the torque command attenuation circuit 14, in accordance with the steering angular velocity sensor 12 is a steering angular speed θ detected ', the attenuation degree of the torque command value T _o changes, attenuation Although the command signal is calculated, the present invention is not limited to this. That may be used torque command value T _o as the steering assist torque. In this case, the configuration of the steering assist device 1 may be a configuration that does not include the steering angular velocity sensor 12 and the torque command attenuation circuit 14.

(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 18.

DESCRIPTION OF SYMBOLS 1 Steering assistance apparatus 2 Target steering angle calculation apparatus 4 Steering angle sensor 6 Margin allowance calculation part 8 Steering angle deviation calculation part 10 Steering assistance torque calculation part 12 Steering angular velocity sensor 14 Torque command attenuation circuit 16 EPS
18 Imaging Circuit 20 Image Processing Circuit 22 Target Route Calculation Circuit 24 Target Steering Angle Calculation Circuit V Own Vehicle B Obstacle

Claims (4)

A target steering angle calculation unit that calculates a target steering angle that is a target rotation angle of the steering wheel of the host vehicle;
A current steering angle detection unit that detects a current steering angle that is a current rotation angle of the steering wheel;
A steering angle deviation calculating unit that calculates a steering angle deviation that is a difference between the target steering angle calculated by the target steering angle calculating unit and the current steering angle detected by the current steering angle detecting unit;
A steering assist torque calculator for calculating a steering assist torque for reducing the steering angle deviation calculated by the steering angle deviation calculator;
A steering support torque output unit that outputs the steering support torque calculated by the steering support torque calculation unit to the steered wheels;
A travel path detection unit for detecting a travel path on which the host vehicle travels;
An obstacle detection unit that detects an obstacle present on at least one of the vehicle width direction right side and the vehicle width direction left side of the host vehicle on the road detected by the travel path detection unit;
The host vehicle has reached a target point that is a point on the target route that the host vehicle is predicted to pass in a state where the rotation angle of the steering wheel is set to the target steering angle on the road detected by the road detection unit. A margin allowance calculation unit that calculates a margin allowance that is a distance between the obstacle detected by the obstacle detection unit and the host vehicle at a time point;
The steering assist torque calculating unit according to claim 1, wherein the steering assist torque calculating unit calculates the steering assist torque to be smaller as the allowance calculated by the allowance calculating unit is larger. The margin allowance calculation unit calculates a margin allowance on the right side in the vehicle width direction of the host vehicle and a margin allowance on the left side in the vehicle width direction of the host vehicle;
The steering assist torque calculating unit calculates the steering assist torque using a smaller margin of the margin on the right side in the vehicle width direction and the margin on the left side in the vehicle width direction calculated by the margin margin calculating unit. The steering assist device for a vehicle according to claim 1.   The vehicle steering assist device according to claim 1, wherein the steering assist torque calculation unit calculates the steering assist torque at a preset torque calculation time interval. A steering angle deviation calculating step for calculating a steering angle deviation that is a difference between a target steering angle that is a target rotation angle of the steering wheel of the host vehicle and a current steering angle that is a current rotation angle of the steering wheel;
A steering assist torque calculating step for calculating a steering assist torque for reducing the steering angle deviation calculated in the steering angle deviation calculating step;
A steering assist torque output step of outputting the steering assist torque calculated in the steering assist torque calculation step to the steered wheels;
When the host vehicle reaches a target point that is a point on the target route that the host vehicle predicts to pass with the rotation angle of the steering wheel set to the target steering angle on the travel path on which the host vehicle travels. A margin allowance calculation step for calculating a margin allowance that is a distance between an obstacle present on at least one of the vehicle width direction right side and the vehicle width direction left side of the host vehicle and the host vehicle;
In the steering assist torque calculating step, the steering assist torque is calculated to be smaller as the allowance calculated in the allowance calculating step is larger.

Images