JP7391475B2 - Steering support device - Google Patents

Description

The present invention relates to a device that supports steering of a vehicle such as an automobile.

Some recent vehicles such as automobiles are equipped with a steering support function that assists in steering. The parking support function that supports parking of the vehicle is one of the functions that uses the steering support function, and the parking support function allows the user of the vehicle to park in a parking space ( Once the target parking position (target parking position) is set, the steering, accelerator, brake, and shift operations are performed so that the vehicle moves along the target trajectory from the current position to the target parking position and is parked at the parking position. It is done automatically.

JP 2019-171959 Publication

If the user indicates an intention to cancel (end) the steering operation using such a parking assist function, priority must always be given to this intention. An example of an operation that indicates the user's intention to cancel is a steering wheel operation, and a method for detecting this steering wheel operation is to use information from a torque sensor (torque sensor value) that is originally installed in the EPS (Electric Power Steering) system. There are methods to use.

However, steering torque may be generated even while the parking assist function is operating the steering wheel, and if the method uses only information from the torque sensor, parking assistance may be stopped by mistake in such cases, making the convenience of the parking assist function less effective. There is a concern that it may decline.

An object of the present invention is to provide a steering support device that can stop steering support according to the user's intention.

In order to achieve the above object, a steering assist device according to the present invention includes a motor that generates a torque applied to the steering of a vehicle, a torque detection means that detects the steering torque of the steering, and a steering angle that detects the steering angle. a steering angle detecting means; a steering assist means for controlling a motor according to the commanded steering angle to perform steering support to match the steering angle with the commanded steering angle; a steering torque detected by the torque detecting means; A steering assistance stopping means is included for stopping steering assistance by the steering assistance means based on a steering angle deviation that is a difference between the steering angle and the steering angle detected by the steering angle detection means.

According to this configuration, the steering assistance is stopped based not only on the steering torque but also on the steering angle deviation, which is a parameter that changes depending on the user's steering wheel operation. Therefore, during steering support, steering torque due to inertia is detected when the steering wheel is moved from a stopped state or turned back, not by the user's steering wheel operation, but by the torque of the motor according to the commanded steering angle. Also, it is possible to prevent the steering support from being stopped. On the other hand, if steering torque and steering angle deviation occur due to a steering wheel operation by the user during steering assistance, steering assistance is stopped based on the steering torque and steering angle deviation.

Therefore, while it is possible to prevent the steering support from being stopped against the user's will, if the steering wheel operation is performed according to the user's will, the steering support can be stopped according to the user's will.

The steering support stop means is a combination of a torque threshold related to the steering torque detected by the torque detection means and a steering angle deviation threshold related to the steering angle deviation, and a time change rate of the steering angle in association with the combination. A time threshold based on a value related to the steering speed is set, and a time period corresponding to the combination in which the steering torque and steering angle deviation detected by the torque detection means are respectively equal to or greater than the torque threshold and the steering angle deviation threshold related to the combination is determined. The configuration may also be such that the steering support is stopped if it continues for more than a threshold value.

According to this configuration, when the steering torque and the steering angle deviation are respectively equal to or higher than the torque threshold and the steering angle deviation threshold and continue for longer than the time threshold, the steering assistance is stopped, so when the steering is turned back due to the steering assistance, the steering assistance is stopped. Even if a temporary steering torque is detected (when the direction of the steering angle is switched), it is possible to prevent the steering support from being stopped against the user's will.

Moreover, since the time threshold is set based on the value related to the steering speed, which is a parameter that changes depending on the user's steering wheel operation, the time threshold is set when the steering torque and steering angle deviation are respectively equal to or higher than the torque threshold and the steering angle deviation threshold. It can be assumed that the situation that continues above is a situation where the user is operating the steering wheel according to his/her intention. Therefore, it is possible to accurately determine whether or not the user has the intention to stop the steering support depending on whether the situation holds true, and it is determined whether or not to stop the steering support based on that determination. By doing so, it is possible to further suppress stopping of the steering support against the user's intention, and it is possible to stop the steering support according to the user's intention.

The time threshold value is preferably set to a smaller value as the value related to the steering speed becomes larger.

As a result, for example, when a user lightly touches a steering wheel that is automatically rotated by steering assistance, the change in the value related to the steering speed is small, so the steering assistance will not be stopped unless that situation continues for a long time. As a result, parking assistance can be further prevented from being stopped against the user's will. On the other hand, if the user manually operates the steering wheel that is automatically rotated by the steering support and rotates it in the opposite direction, the value related to the steering speed will change significantly, so the steering support should be stopped promptly according to the user's intention. be able to.

According to the present invention, while it is possible to prevent steering support from being stopped against the user's will, when a steering wheel operation is performed according to the user's will, the steering support is stopped according to the user's will. be able to.

FIG. 1 is a block diagram schematically showing a configuration related to steering of a vehicle equipped with a steering support device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration related to a parking support function. FIG. 6 is a diagram showing a first condition for determining whether to stop the parking assist operation. FIG. 6 is a diagram illustrating a second condition under which it is determined whether the parking assist operation should be stopped. FIG. 7 is a diagram showing a third condition under which it is determined whether the parking assist operation should be stopped. FIG. 7 is a diagram showing a fourth condition under which it is determined whether the parking assist operation should be stopped.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<Steering configuration>
FIG. 1 is a block diagram schematically showing a configuration related to steering of a vehicle 1 according to an embodiment of the present invention.

The vehicle 1 is equipped with an electric power steering device 2. An electric power steering device (EPS: Electric Power Steering) 2 includes an electric motor M and a steering wheel 3, and applies torque generated by the electric motor M to the steering wheel 3 to control steering wheels of the vehicle 1 (for example, This is a device that steers the left and right front wheels.

The steering wheel 3 includes a handle (steering wheel) 4, a steering gear mechanism 5, and a steering shaft 6.

The handle 4 is, for example, a steering wheel rotated by the driver to steer the vehicle 1, and is disposed in front of the driver's seat in the vehicle interior.

The steering gear mechanism 5 is, for example, a mechanism including a rack and pinion type steering gear.

The steering shaft 6 is provided to penetrate inside and outside the vehicle interior. The upper end of the steering shaft 6 is connected to the handle 4. A lower end portion of the steering shaft 6 is connected to the steering gear mechanism 5. When the steering gear mechanism 5 includes a rack-and-pinion type steering gear, the lower end of the steering shaft 6 is connected to the pinion of the steering gear in a relatively non-rotatable manner.

Further, the vehicle 1 is equipped with an EPSECU 7. The EPSECU 7 is an ECU (Electronic Control Unit) that mainly controls the electric power steering device 2 (electric motor M). In addition to the EPSECU 7, the vehicle 1 is equipped with a plurality of ECUs, such as an IPA (Intelligent Parking Assist) ECU 8 shown in FIG. 2, in order to control various parts. These ECUs are connected to enable bidirectional communication using a CAN (Controller Area Network) communication protocol.

The EPSECU 7 includes a microcomputer (microcontroller unit) 11 that includes a CPU and a memory, and a motor drive circuit 12 that includes an H-bridge circuit.

Various sensors necessary for control are connected to the microcomputer 11. The various sensors include, for example, a torque sensor 13 and a steering angle sensor 14.

The torque sensor 13 is provided in connection with the torsion bar 15 interposed in the middle of the steering shaft 6, and detects the magnitude and direction of twist occurring in the torsion bar 15 as a steering torque, and detects the magnitude and direction of the twist occurring in the torsion bar 15 as a steering torque. Outputs a detection signal.

The steering angle sensor 14 outputs, for example, a detection signal according to the steering angle (absolute steering angle) of the steering wheel 4 with respect to the midpoint of the steering angle of the steering wheel 4 (the steering angle of the steering wheel 3). For example, the steering angle detected by the steering angle sensor 14 takes a positive value when the steering wheel 4 is turned to the right from the midpoint of the steering angle, and takes a negative value when the steering wheel 4 is turned to the left.

The microcomputer 11 sets a current target value based on information acquired from detection signals of various sensors and/or various information input from other ECUs, and the drive current corresponding to the current target value is applied to the electric motor M. The switching of the switching element included in the motor drive circuit 12 is controlled so that the motor drive circuit 12 is supplied with the motor.

<Parking support function>
FIG. 2 is a block diagram showing the configuration related to the parking support function.

The vehicle 1 has a parking support function (automatic parking function). The function processing unit for the parking assistance function includes, for example, a surrounding object detection unit, a parking area detection unit, a target parking position setting unit, a vehicle position estimation unit, a parking trajectory calculation unit, a steering control unit, and a driver information provision unit. included. Among these functional processing units, the EPSECU 7 is responsible for the function of the steering control unit, and the IPAECU 8 is responsible for the functions of the functional processing units other than the steering control unit, that is, the surrounding object detection unit, the parking area detection unit, and the target parking position setting unit. , a vehicle position estimation section, a parking trajectory calculation section, and a driver information provision section.

The surrounding object detection unit detects objects around the vehicle 1 from information captured by the on-vehicle camera, and also detects information including the shape of the object and the distance to the object (information around the vehicle 1). . As vehicle-mounted cameras, the vehicle 1 is provided with a front camera that photographs the front of the vehicle 1, a back camera that photographs the rear of the vehicle 1, and a side camera that photographs the left and right sides of the vehicle 1.

The parking area detection unit detects a plurality of parking areas around the vehicle 1 where the vehicle 1 can be parked based on the surrounding information generated by the surrounding object detection unit.

The target parking position setting unit sets a target parking position in a parking area selected by the user from among the parking areas detected by the parking area detection unit.

For example, the own vehicle position estimation unit receives a positioning signal from a GNSS (Global Navigation Satellite System) satellite using a GNSS antenna, and determines the positioning signal based on the vehicle speed, steering angle, and longitudinal G of the positioning signal received by the GNSS antenna. The current position of the vehicle 1 (self-vehicle position) is estimated from either or a combination of the navigation calculation results.

The parking trajectory calculation unit calculates a target trajectory of the vehicle 1 from the own vehicle position estimated by the own vehicle position estimation unit to the target parking position set by the target parking position setting unit, and adjusts the steering wheel 3 according to the target trajectory. Set the commanded rudder angle, which is the target value of the rudder angle. This set instruction steering angle is input from the IPAECU 8 to the EPSECU 7.

The steering control section controls the steering of the vehicle 1 based on the instructed steering angle.

The driver information providing unit displays images of the surroundings of the vehicle 1 and the parking area on the display. The display may be anything that is placed at a position that is visible to the driver, such as a multi-information display built into a combination meter. When the parking area detection unit detects a parking area in which the vehicle 1 can be parked, the driver information providing unit causes the display to display an image of the area around the vehicle 1 including the detected parking area. The user selects a parking area on the display where this image is displayed.

After selecting a parking area, when an instruction to perform parking assistance using the parking assistance function is given on the display, the parking assistance operation is started.

The microcomputer 11 of the EPSECU 7 includes a basic assist amount calculation section 21, a compensation system assist amount calculation section 22, a steering angle servo control section 23, and a steering angle servo stop determination section 24 as functional processing sections realized in software through program processing. substantially.

The basic assist amount calculating section 21 calculates a basic assist amount according to the steering torque detected by the torque sensor 13 (steering torque acquired from the detection signal of the torque sensor 13) and the vehicle speed of the vehicle 1. Specifically, a basic assist map that defines the characteristics of the basic assist amount with respect to the steering torque is prepared for each of a plurality of vehicle speed ranges, and the basic assist amount calculation unit 21 calculates the basic assist amount according to the vehicle speed of the vehicle 1. An assist map is selected, and a basic assist amount corresponding to the steering torque detected by the torque sensor 13 is calculated according to the selected basic assist map. The vehicle speed may be transmitted to the EPSECU 7 from another ECU, or a vehicle speed sensor that outputs a detection signal according to the vehicle speed may be connected to the EPSECU 7, and the vehicle speed may be acquired from the detection signal of the vehicle speed sensor.

The compensation system assist amount calculation unit 22 calculates the steering torque detected by the torque sensor 13, the steering angle detected by the steering angle sensor 14 (the steering angle acquired from the detection signal of the steering angle sensor 14, and the rotation speed of the electric motor M). The motor rotation speed is used to calculate the compensation system assist amount that gives a feeling of response during steering (steering wheel operation).The motor rotation speed is determined by the voltage between the terminals of the electric motor M and the winding of the electric motor M. It is estimated from the motor current value, which is the flowing current value.

The rudder angle servo control unit 23 adjusts the rudder angle detected by the rudder angle sensor 14 and the commanded rudder angle so that the rudder angle detected by the rudder angle sensor 14 matches the commanded rudder angle input from the IPAECU 8 to the EPSECU 7. A steering angle control amount is calculated according to the deviation.

Then, in the microcomputer 11, the basic assist amount calculated by the basic assist amount calculating section 21 and the compensation system assist amount calculated by the compensation system assist amount calculating section 22 are added, and the sum is calculated by the steering angle servo control section 23. The steering angle control amount is further added, and the added value is used as the target value of the current supplied to the electric motor M, and is included in the motor drive circuit 12 according to the deviation between the current target value and the motor current value. Switching of the switching element is controlled. Thereby, a drive current corresponding to the current target value is supplied from the motor drive circuit 12 to the electric motor M of the electric power steering device 2.

Note that when the user is not operating the steering wheel 4 (steering wheel operation) and the steering torque detected by the torque sensor 13 is 0, the basic assist amount calculated by the basic assist amount calculating section 21 and the compensation system The compensation system assist amounts calculated by the assist amount calculation section 22 are both zero. Therefore, during the parking assist operation, basically, the steering angle control amount calculated by the steering angle servo control section 23 is set as the current target value, so that the steering angle of the steering wheel 4 matches the commanded steering angle. A drive current is supplied to the electric motor M from the motor drive circuit 12.

The steering angle servo stop determination unit 24 determines whether or not to stop the parking assistance operation while the parking assistance operation is being performed. Specifically, the steering torque detected by the torque sensor 13 is used for the stop determination. In addition, a steering angle deviation, which is the difference between the steering angle (actual steering angle) detected by the steering angle sensor 14 and the commanded steering angle input from the IPAECU 8 to the EPSECU 7, is determined, and the steering angle deviation is used for stopping determination. be done. In the stop determination, if any of the conditions shown in FIG. 3, FIG. 4, FIG. 5, and FIG. is determined to have stopped. When the steering angle servo stop determination section 24 determines that the parking assist operation should be stopped, the steering angle control amount calculated by the steering angle servo control section 23 is set to 0, and the parking assistance operation is stopped.

The condition shown in FIG. 3 is a condition that is satisfied when steering torque is generated as a result of the user operating the steering wheel 4 with the intention of stopping the parking assist operation, and is detected by the torque sensor 13, for example. The condition is that a state in which the applied steering torque is equal to or greater than a predetermined torque threshold continues for a predetermined detection time threshold or longer. Under this condition, the value of the rudder angle deviation, which is the difference between the rudder angle detected by the rudder angle sensor 14 and the commanded rudder angle, does not matter; however, by setting the rudder angle deviation threshold to 0, the rudder angle deviation It can also be considered that the condition that is greater than or equal to the steering angle deviation threshold always holds true.

The condition shown in FIG. 4 is that the steering angle (rotation angle) of the steering wheel 4 is changed to the target steering angle of the steering wheel 4 due to the parking assistance operation because the user operates the steering wheel 4 with the intention of stopping the parking assistance operation. For example, a state in which the steering angle deviation, which is the difference between the steering angle detected by the steering angle sensor 14 and the instructed steering angle, is greater than or equal to a predetermined steering angle deviation threshold is a condition that is satisfied when the steering angle deviates from the steering angle sensor 14. The condition is that the condition continues for a time threshold (for example, the same time as in the condition shown in FIG. 3). Under this condition, the value of the steering torque detected by the torque sensor 13 does not matter; however, by setting the torque threshold to 0, it is considered that the condition that the steering torque is equal to or greater than the torque threshold always holds true. You can also do that.

The conditions shown in FIG. 5 are such that when the steering wheel 4 is rotated due to the parking assistance operation, the user operates the steering wheel 4 with the intention of stopping the parking assistance operation, and the steering wheel 4 rotates in the opposite direction. A steering angle deviation is a condition that is satisfied, for example, the steering torque detected by the torque sensor 13 is equal to or higher than a predetermined torque threshold, and the steering angle deviation is the difference between the steering angle detected by the steering angle sensor 14 and the commanded steering angle. The condition is that the state in which the steering angle deviation is greater than or equal to a predetermined steering angle deviation threshold continues for a predetermined detection time threshold or longer.

The condition shown in FIG. 6 is satisfied when the rotation of the steering wheel 4 is stopped due to the user operating the steering wheel 4 with the intention of stopping the parking assistance operation when the steering wheel 4 is rotated due to the parking assistance operation. For example, the steering torque detected by the torque sensor 13 is equal to or higher than the torque threshold value, which is lower than the condition shown in FIG. This condition is such that the state in which the steering angle deviation, which is the difference, is equal to or greater than the steering angle deviation threshold, which is lower than the condition shown in FIG. 5, continues for a detection time threshold or longer, which is longer than the condition shown in FIG.

Note that the detection time threshold under each condition shown in FIGS. 3 to 6 is set variably, and the larger the steering speed, which is the time rate of change in the steering angle detected by the steering angle sensor 14, is The detection time threshold under each condition shown in is set to a small value.

<Effect>
As described above, the steering support is stopped based not only on the steering torque but also on the steering angle deviation, which is a parameter that changes depending on the user's steering wheel operation. Specifically, if the state in which the steering torque and the steering angle deviation exceed the torque threshold and the steering angle deviation threshold, respectively, continues for a time threshold or more, the steering assistance is stopped. Therefore, during steering support, when the steering wheel 4 is moved from a stopped state or turned back by the torque of the electric motor M according to the commanded steering angle rather than by the steering wheel operation by the user, temporary steering torque due to inertia is generated. Even if detected, steering support can be prevented from being stopped. On the other hand, if steering torque and steering angle deviation occur due to a steering wheel operation by the user during steering assistance, steering assistance is stopped based on the steering torque and steering angle deviation.

Therefore, while it is possible to prevent the steering support from being stopped against the user's will, if the steering wheel operation is performed according to the user's will, the steering support can be stopped according to the user's will.

Furthermore, the time threshold used to determine whether or not to stop the parking assist operation is set based on the value related to the steering speed, which is a parameter that changes depending on the user's steering wheel operation, so the steering torque and steering angle deviation are A situation in which the torque threshold and the steering angle deviation threshold, respectively, continue for longer than the time threshold can be estimated to be a situation in which the user is operating the steering wheel according to his/her intention. Therefore, it is possible to accurately determine whether or not the user has the intention to stop the steering support depending on whether the situation holds true, and it is determined whether or not to stop the steering support based on that determination. By doing so, it is possible to further suppress stopping of the steering support against the user's intention, and it is possible to stop the steering support according to the user's intention.

Further, the time threshold value is set to a smaller value as the value related to the steering speed becomes larger. As a result, for example, if the user lightly touches the steering wheel that rotates automatically with steering assistance (if the conditions shown in Figure 6 are met), the change in the value related to the steering speed is small, so the situation will last for a long time. If this does not continue, the steering support will not be stopped. As a result, parking assistance can be further prevented from being stopped against the user's will. On the other hand, if the user manually operates the steering wheel that automatically rotates with steering assistance and rotates it in the opposite direction (if the conditions shown in Figure 5 are met), the value related to the steering speed will change significantly, so the user The steering support can be stopped promptly according to the driver's intention.

<Modified example>

Although one embodiment of the present invention has been described above, the present invention can also be implemented in other forms.

と表されるので、操舵加速度ｄω／ｄｔは、

と表すことができ、操舵速度ωは、

と表すことができるので、駐車支援動作を停止させるか否かの判定に使用される時間閾値ｔは、

に従って設定されてもよい。これにより、駐車支援動作を停止させるか否かの判定におけるロバスト性を向上することができる。また、ハンドル４の舵角をθとした場合、［数４］の式は、

と表すことができる。 For example, if the moment of inertia of the steering wheel 4 is J [Nm・s ² /rad], the steering torque Trq [Nm] is

Therefore, the steering acceleration dω/dt is

It can be expressed as, and the steering speed ω is

Therefore, the time threshold t used to determine whether to stop the parking assist operation is:

may be set according to Thereby, it is possible to improve the robustness in determining whether or not to stop the parking assist operation. Moreover, when the steering angle of the steering wheel 4 is set to θ, the formula [Equation 4] is

It can be expressed as.

に従って設定されてもよい。 In addition, in order to further suppress erroneous determination of whether or not to stop the parking assistance operation, the time threshold t used for determining whether or not to stop the parking assistance operation is set as follows.

may be set according to

In addition, various design changes can be made to the above-described configuration within the scope of the claims.

1: Vehicle 3: Steering 8: ECU (steering support device)
11: Microcomputer (steering support means, steering support stop means)
13: Torque sensor (torque detection means)
14: Rudder angle sensor (rudder angle detection means)
23: Rudder angle servo control unit (steering support means)
24: Rudder angle servo stop determination unit (steering support stop means)
M: Electric motor (motor)

Claims (2)

a motor that generates torque applied to the vehicle's steering;
Torque detection means for detecting the steering torque of the steering wheel;
Rudder angle detection means for detecting a rudder angle of the steering wheel;
Steering support means that controls the motor according to the commanded steering angle to perform steering support to match the steering angle of the steering wheel with the commanded steering angle;
The steering assistance by the steering assistance means is performed based on the steering torque detected by the torque detection means and the steering angle deviation that is the difference between the commanded steering angle and the steering angle detected by the steering angle detection means. a steering support stop means for stopping the steering support,
The steering support stop means includes:
A combination of a torque threshold related to the steering torque detected by the torque detection means and a steering angle deviation threshold related to the steering angle deviation, and a combination related to the steering speed, which is a time change rate of the steering angle, in association with the combination. Set a time threshold based on the value,
If the state in which the steering torque and the steering angle deviation detected by the torque detection means are respectively greater than or equal to the torque threshold and the steering angle deviation threshold associated with the combination continues for longer than the time threshold corresponding to the combination; A steering support device that stops steering support. The steering support device according to claim 1 , wherein the time threshold is set to a smaller value as the value related to the steering speed becomes larger.

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