JP7344008B2 - Steering control device, steering control method, and steering control system - Google Patents

Description

The present invention relates to a steering control device, a steering control method, and a steering control system that control steering angles of front wheels and rear wheels of a vehicle.

The four-wheel vehicle disclosed in Patent Document 1 includes a front wheel steering actuator that applies a steering force when steering the front wheels, and a rear wheel steering actuator that applies a steering force when steering the rear wheels. , a drive control section that performs drive control of a front wheel steering actuator and a rear wheel steering actuator, and a guidance support control section that performs support control for guiding a four-wheeled vehicle along a predetermined route in cooperation with the drive control section. Be prepared.

Japanese Patent Application Publication No. 2015-214179

By the way, in front and rear wheel steering control that guides the vehicle along a route based on external world information (surrounding environment) of the vehicle, if the steering angle of the rear wheels is set independently of the steering angle of the steering wheel by the driver, obstacles Even if guidance such as avoidance is possible, vehicle behavior that has no correlation with the driver's steering wheel operations may cause the driver to feel uncomfortable.

The present invention has been made in view of the conventional situation, and its purpose is to provide a steering control that can suppress a driver's discomfort when guiding a vehicle along a route based on information about the outside world of the vehicle. An object of the present invention is to provide an apparatus, a steering control method, and a steering control system.

According to one aspect of the present invention, a physical quantity related to a reference turning radius at a reference position preset in the vehicle is determined according to the obtained steering angle of the steering wheel, and based on the physical quantity related to the reference turning radius, determining a standard distribution of the steering angle of the front wheels and the steering angle of the rear wheels , and acquiring information on the relative position of the vehicle with respect to an obstacle in front of the vehicle from among the external world information of the vehicle acquired by the external world recognition unit; Based on the relative position information, a front wheel steering command and a rear wheel steering command are provided to change the distribution of the front wheel steering angle and the rear wheel steering angle with respect to the standard distribution while maintaining the standard turning radius. When information regarding the obstacle on the outside of the turn of the vehicle is obtained, the steering angle of the front wheels is decreased with respect to the reference distribution, and the steering angle of the rear wheels is determined as the steering angle of the rear wheels. The steering angle of the front wheels increases in opposite phase to the steering angle of the front wheels, and as the relative position moves from the front to the rear of the vehicle, the steering angle of the front wheels increases with respect to the steering angle of the rear wheels. It is characterized by obtaining a steering command and a rear wheel steering command .
Further, according to the present invention, in one aspect, a physical quantity related to a reference turning radius at a reference position set in advance for the vehicle is determined according to the obtained steering angle of the steering wheel, and based on the physical quantity related to the reference turning radius. A standard distribution of the steering angle of the front wheels and the steering angle of the rear wheels is determined, and information on the relative position of the vehicle with respect to an obstacle in front of the vehicle is obtained from among the external world information of the vehicle acquired by the external world recognition unit. and a front wheel steering command for changing the distribution of the steering angle of the front wheels and the steering angle of the rear wheels with respect to the standard distribution while maintaining the standard turning radius based on the information on the relative position. and a rear wheel steering command, and when information regarding the obstacle on the inside of a turn of the vehicle is acquired, the steering angle of the front wheels is decreased with respect to the reference distribution, and the steering angle of the rear wheels is determined. is increased in an opposite phase to the steering angle of the front wheels, and as the relative position moves from the center of the vehicle to the rear, the steering angle of the front wheels increases with respect to the steering angle of the rear wheels. , which is characterized by determining a front wheel steering command and a rear wheel steering command.
Further, according to the present invention, in one aspect, a physical quantity related to a reference turning radius at a reference position set in advance for the vehicle is determined according to the obtained steering angle of the steering wheel, and based on the physical quantity related to the reference turning radius. A standard distribution of the steering angle of the front wheels and the steering angle of the rear wheels is determined, and information on the relative position of the vehicle with respect to an obstacle in front of the vehicle is obtained from among the external world information of the vehicle acquired by the external world recognition unit. However, if there is an obstacle on the inside of the turning radius of the vehicle, the distribution of the front wheel steering angle and the rear wheel steering angle is changed with respect to the standard distribution, and the vehicle is rotated while maintaining the standard turning radius. A front wheel steering command and a rear wheel steering command are determined to increase the innermost turning radius of the traveling trajectory of the vehicle to prevent contact between the vehicle and the obstacle, and determine a front wheel steering command and a rear wheel steering command to prevent the vehicle from coming into contact with an obstacle. In this case, the distribution of the steering angle of the front wheels and the steering angle of the rear wheels is changed with respect to the standard distribution, and the outermost turning radius of the traveling trajectory of the vehicle is decreased while the standard turning radius is maintained. The present invention is characterized in that the front wheel steering command and the rear wheel steering command are determined to prevent the vehicle from coming into contact with an obstacle.

According to the present invention, it is possible to suppress a driver's discomfort when guiding a vehicle along a route based on external world information of the vehicle.

1 is a diagram showing a vehicle equipped with a steering control system. FIG. 2 is a block diagram showing the configuration of a steering control system. FIG. 3 is a state diagram showing changes in steering angle when an obstacle exists on the outside of the turning of the vehicle. 5 is a time chart showing changes in the steering angles of the front and rear wheels and the outermost turning radius of the vehicle when an obstacle exists on the outside of the turning of the vehicle. FIG. 6 is a diagram showing the turning center when the front wheels are steered with the rear wheels in a neutral position. FIG. 6 is a diagram showing the turning center when the rear wheels are steered and the front wheels are placed in a neutral position. FIG. 4 is a state diagram showing changes in steering angle when an obstacle exists on the inside of a turn of the vehicle. 5 is a time chart showing changes in the steering angles of the front and rear wheels and the innermost turning radius of the vehicle when an obstacle exists on the inside of the turning of the vehicle. It is a figure which shows the turning center when a front wheel is steered and a rear wheel is steered in the opposite phase to a front wheel. 3 is a flowchart showing a procedure for front and rear wheel steering control.

Hereinafter, embodiments of a steering control device, a steering control method, and a steering control system according to the present invention will be described based on the drawings.
FIG. 1 is a schematic diagram of a vehicle 1 equipped with a steering control system.

A vehicle 1 in FIG. 1 is a four-wheeled vehicle that includes a pair of left and right front wheels 2, 2 and a pair of left and right rear wheels 3, 3.
The vehicle 1 includes a front wheel steering device 5 that controls the steering angle of the front wheels 2, 2, and a rear wheel steering device 6 that controls the steering angle of the rear wheels 3, 3.

Both the front wheel steering device 5 and the rear wheel steering device 6 are steer-by-wire type steering devices that have no mechanical connection between the steering wheel 4 and the steered wheels, and are powered by an electric motor or the like that generates steering force. Steering actuators 5A and 6A are provided, respectively.
In other words, the steering control system can control the steering angles of the front and rear wheels to a steering angle that is uniquely determined according to the steering angle of the steering wheel 4. can be controlled to any arbitrary steering angle.

The front wheel steering device 5 and the rear wheel steering device 6 control the steering angle of the steered wheels by having a steering actuator generate a steering force in response to a command from the steering control device 7.
Note that the front wheel steering device 5 may include a backup mechanism that mechanically connects the steering wheel 4 and the front wheels 2, 2 with a clutch or the like in the event of a system abnormality.

The steering control device 7 is an electronic control device mainly composed of a microcomputer equipped with a processor, memory, I/O, and a bus connecting these devices, and performs calculations based on various input information and generates steering commands as the calculation results. It has a function as a control section that outputs the information to the front wheel steering device 5 and the rear wheel steering device 6.
The steering control device 7 receives various operation information of the driver including the steering angle of the steering wheel 4, information regarding the driving state of the vehicle 1 such as acceleration, and external world information of the vehicle 1 (surrounding environment information) acquired by the external world recognition device 8. information), etc.

The external world recognition device 8 is an external world recognition unit that acquires external world information regarding obstacles, parking positions, etc. of the vehicle 1 using an external world detection device such as a camera.
The outside world recognition device 8 includes a first outside world recognition sensor 8A installed at the front of the vehicle 1 to acquire outside world information in front of the vehicle 1, and a first outside world recognition sensor 8A installed at the rear of the vehicle 1 to acquire outside world information behind the vehicle 1. A second outside world recognition sensor 8B installed, a third outside world recognition sensor 8C installed on the right side of the vehicle 1 to acquire outside world information on the right side of the vehicle 1, and a third outside world recognition sensor 8C installed on the right side of the vehicle 1 to acquire outside world information on the left side of the vehicle 1. Therefore, a fourth external world recognition sensor 8D installed on the left side of the vehicle 1 is provided to acquire external world information in all directions of the vehicle 1.

However, when using a camera as an external world recognition sensor, the number of installed external world recognition sensors can be increased or decreased as appropriate depending on the viewing angle of the camera, and the configuration is not limited to installing four cameras on four sides of the vehicle 1.
Further, the steering control device 7 can acquire external world information of the vehicle 1 from outside the vehicle 1.

Here, the external world information regarding obstacles acquired by the external world recognition device 8 includes information regarding the relative position of the vehicle 1 with respect to the obstacle in front of the vehicle 1.
The external world recognition unit determines the relative position of the vehicle 1 with respect to an obstacle in front of the vehicle 1 based on recognition of a parking lot based on a combination of position information of the vehicle 1 acquired by GPS (Global Positioning System) and map data, etc. Information regarding location can be obtained.

The steering control device 7 has a normal steering control function that mainly controls the steering angle of the front wheels 2, 2 according to the steering angle of the steering wheel 4.
Furthermore, while the vehicle 1 is turning, the steering control device 7 automatically changes the steering angles of the front and rear wheels in order to avoid the vehicle 1 from coming into contact with obstacles existing on the outside or inside of the turn. It has a contact avoidance support function that guides the vehicle 1 along a route that avoids obstacles.

Here, in normal steering angle control, the steering control device 7 sets the steering angles of the rear wheels 3, 3 to a neutral position (steering The steering angle of the front wheels 2, 2 is controlled in accordance with the steering angle of the steering wheel 4 while maintaining the angle = 0).
That is, the steering angle distribution (reference distribution) in normal steering angle control is set to front wheel steering angle:rear wheel steering angle=100:0 when expressed as a ratio of absolute values of steering angles.

However, the steering control device 7 can perform rear wheel steering also in normal steering angle control according to the steering angle of the steering wheel 4.
In other words, the steering angle distribution (standard distribution) in normal steering angle control is set to, for example, front wheel steering angle: rear wheel steering angle = 90:10, or depending on the steering angle of the steering wheel 4, etc. A system may be used in which the steering angle distribution (standard distribution) is changed.

On the other hand, in the contact avoidance support function, the steering control device 7 controls the steering angle of the front wheels 2, 2 and the steering angle of the rear wheels 3, 3 while maintaining a reference turning radius, which is a turning radius at a reference position preset for the vehicle 1. By changing the steering angle distribution from the standard distribution, the diameter of the outermost or innermost circumference of the turning locus of the vehicle 1 is changed, and the vehicle 1 during turning is prevented from coming into contact with an obstacle.
Here, even if the collision avoidance support function changes the steering angle distribution between the front and rear wheels, the standard turning radius is maintained, so vehicle behavior that has no correlation with the driver's steering wheel operation occurs, making the driver feel uncomfortable. can be prevented from giving.

Note that in this embodiment, the reference position of the turning radius of the vehicle 1 is set at the center of the vehicle 1.
However, the reference position for the turning radius of the vehicle 1 is not limited to the center of the vehicle 1, and can be set at the driver's seat of the vehicle 1, the rear seat of the vehicle 1, etc. It can also be configured so that it can be changed accordingly.

When normal steering control is performed that mainly controls the steering angle of the front wheels 2, 2 according to the steering angle of the steering wheel 4, the outermost corner of the turning trajectory at the front end of the vehicle is the outermost circumference of the turning trajectory, and the outermost corner of the turning trajectory at the rear end of the vehicle is The inside is the innermost circumference of the turning trajectory.
If an obstacle exists on the outside or inside of the turn of the vehicle 1, there is a possibility that the front end of the vehicle on the outside of the turn or the rear end of the vehicle on the inside of the turn may come into contact with the obstacle due to the driver's carelessness.

Therefore, the steering control device 7 predicts whether or not the vehicle 1 will come into contact with an obstacle while turning, based on the steering angle of the steering wheel 4 and information regarding the obstacle acquired by the external world recognition device 8. .
When the steering control device 7 predicts that the vehicle 1 will come into contact with an obstacle while turning, the steering control device 7 changes the steering angle distribution between the front and rear wheels from the standard distribution while maintaining the standard turning radius. Contact avoidance support control is performed by changing the outermost radius or innermost radius of the travel trajectory to avoid the vehicle 1 from coming into contact with an obstacle while turning.
Note that the contact avoidance support control will be explained in more detail later.

FIG. 2 is a functional block diagram of the steering control device 7 that implements contact avoidance support control.
The steering control device 7 includes functions as an information processing section 7A, a target steering angle calculation section 7B, and an actuator control section 7C as software.
In addition to the external world information acquired by the external world recognition device 8, the information processing unit 7A receives information regarding the driving state of the vehicle 1 and information regarding the driving operation of the vehicle 1 by the driver 10.

Here, the information regarding the driving state of the vehicle 1 includes information on the traveling speed (vehicle speed) VSP of the vehicle 1, information on the acceleration G of the vehicle 1 in the longitudinal direction and the lateral direction, and the like.
Information on the vehicle speed VSP is acquired by the vehicle speed sensor 13, and information on the acceleration G is acquired by the acceleration sensor 14.

Further, the information regarding the driving operation of the driver 10 includes information on the operation of the accelerator pedal 11 by the driver 10, information on the operation of the brake pedal 12 by the driver 10, information on the steering angle of the steering wheel 4 by the driver 10, etc. .
Operation information of the accelerator pedal 11 is acquired by an accelerator opening sensor 15, operation information of the brake pedal 12 is acquired by a brake operation sensor 16, and steering angle information of the steering wheel 4 is acquired by a steering angle sensor 17.
Further, the information processing section 7A has a storage section that stores specification information of the vehicle 1.

As a contact avoidance support function, the information processing unit 7A performs a collision avoidance support function based on input information such as information regarding the driving state of the vehicle 1, information regarding the driving operation of the driver 10, and external world information, as well as specification information of the vehicle 1. Predict information about the travel route from the current location.
The information processing unit 7A then uses the information regarding the obstacle acquired by the external world recognition device 8, specifically, the information regarding the relative position of the vehicle 1 with respect to the obstacle in front of the vehicle 1, and the predicted movement route of the vehicle 1. Based on this information, it is predicted whether or not the vehicle 1 will come into contact with an obstacle if the vehicle 1 continues to turn.

When the information processing unit 7A predicts a contact between the vehicle 1 and an obstacle, the information processing unit 7A performs control to change the steering angle distribution while maintaining the reference turning radius, thereby changing the outermost radius or the innermost radius of the vehicle travel trajectory. It is determined whether the radius can be changed by a length sufficient to avoid contact between the vehicle 1 and an obstacle.
Here, in the control of changing the steering angle distribution while maintaining the reference turning radius, the outermost radius or the innermost radius of the vehicle travel trajectory is set to a length sufficient to avoid contact between the vehicle 1 and an obstacle. If the collision between the vehicle 1 and the obstacle cannot be avoided, the steering control device 7 prioritizes contact avoidance over maintaining the standard turning radius and changes the turning radius of the front and rear wheels. Steering control is performed to guide the vehicle 1 along a route avoiding obstacles.

If contact between the turning vehicle 1 and an obstacle is predicted, the target steering angle calculation unit 7B can avoid contact between the vehicle 1 and the obstacle while maintaining the predicted movement route and the reference turning radius. Based on the judgment result, a corrected movement path (target trajectory) for avoiding obstacles is generated by correcting the predicted movement path, and a time-series front and rear wheel steering command ( Find the target steering angles for the front and rear wheels.
The actuator control unit 7C controls the steering actuator of the front wheel steering device 5 based on the command for the front wheel steering angle determined by the target steering angle calculation unit 7B, and adjusts the steering angle of the front wheels 2, 2 to the command value. Further, the actuator control unit 7C controls the steering actuator of the rear wheel steering device 6 based on the rear wheel steering angle command obtained by the target steering angle calculation unit 7B, and adjusts the steering angle of the rear wheels 3 to the command value. Adjust to.

Note that the external world recognition device 8 can acquire recognition information of obstacles through image processing using a monocular camera, and can also acquire information regarding obstacles using an external world recognition device that is a shape recognition device such as a stereo camera or a laser radar. You can also.
In addition, if the vehicle 1 is equipped with an automatic parking device (electronic control device) that automatically performs parking operations (accelerator operation, brake operation, and front wheel steering) based on the recognition information of the parking position acquired by the external world recognition device 8, the steering control The device 7 can perform contact avoidance support control to avoid obstacles without changing the turning radius of the vehicle 1 during an automatic parking operation by such an automatic parking device.

In the following, the process of changing the steering angle distribution in the contact avoidance support control will be described in detail.
First, a process for changing steering angle distribution when avoiding an obstacle on the outside of a turn will be described.
FIG. 3 is a state diagram showing how the steering angles of the front and rear wheels change when a steering angle distribution change process is performed to avoid an obstacle on the outside of the turn.
Further, FIG. 4 is a time chart showing changes in the steering angle and the turning radius when the steering angle distribution changing process is carried out to avoid obstacles on the outside of the turn.

As shown in FIG. 3, the front wheels 2, 2 are steered to a steering angle corresponding to the steering angle of the steering wheel 4, and the rear wheels 3, 3 are in the neutral position during normal turning, in other words, the reference During steering control based on distribution, the outer front end of the vehicle 1 turns on the outermost side (outermost circumference).
Here, when the steering control device 7 detects an obstacle on the outside of the turning front of the vehicle 1, the steering control device 7 detects that the obstacle is located at the outermost periphery of the travel trajectory of the vehicle 1, that is, the turning trajectory on the outside of the front end of the vehicle 1 (see FIG. It is determined whether or not the outside of the front end of the vehicle 1 will come into contact with an obstacle if the vehicle 1 continues to make the turn.

Furthermore, when the steering control device 7 predicts that the outer front end of the vehicle 1 will come into contact with an obstacle, it is possible to avoid the obstacle by controlling the steering angle distribution to be changed while maintaining the reference turning radius. Whether or not there is an obstacle is determined based on the turning radius of the outermost circumference of the vehicle that can avoid the obstacle (Rout2 in FIG. 3), in other words, the distance from the turning center of the vehicle 1 to the inside of the obstacle.
Then, if it is possible to avoid the obstacle while maintaining the standard turning radius, the steering control device 7 changes the distribution of the steering angle of the front wheels 2, 2 and the steering angle of the rear wheels 3, 3 from the standard distribution. A front wheel steering command and a rear wheel steering command are output to the front wheel steering device 5 and the rear wheel steering device 6, respectively.

When the front wheels 2, 2 are steered and the rear wheels 3, 3 are placed in the neutral position, the turning center of the vehicle 1 is on the extension line of the axle of the rear wheels 3, 3, as shown in Fig. 5, and the turning The outside of the front end of the vehicle, which is farthest from the center, turns on the outermost side (outermost circumference), and the inside of the rear end of the car body turns on the innermost side (innermost circumference).
On the other hand, when the steering angle of the front wheels 2, 2 is set to the neutral position and the rear wheels 3, 3 are steered in opposite phases, the turning center of the vehicle 1 is set to the axle of the front wheels 2, 2, as shown in FIG. As an extension of this, the outside of the rear end of the vehicle that is farthest from the turning center will turn on the outermost edge (outermost circumference), and the inner side of the front end of the vehicle will turn on the innermost edge (innermost circumference).

Therefore, when an obstacle exists on the outside of the turn of the vehicle 1, the steering control device 7 reduces the steering angle of the front wheels 2, 2 to return them to near the neutral position before the front end of the vehicle 1 reaches the obstacle. The steering angle of the rear wheels 3, 3 is increased in the opposite phase to the steering angle of the front wheels 2, 2, and as shown in FIG. In this state, the front end of the vehicle 1 is made to reach the obstacle.

Thereafter, the steering control device 7 causes the steering angle of the front wheels 2, 2 to become larger than the steering angle of the rear wheels 3, 3 as the relative position of the vehicle 1 with respect to the obstacle moves from the front to the rear of the vehicle 1. so that the steering angle is gradually returned to the standard steering angle.
In the process of returning to this standard distribution, the innermost part of the side of the car body that turns on the outside of the turn moves from the front of vehicle 1 to the rear, so this innermost part of the side that turns is closest to the obstacle. By changing the distribution in accordance with changes in the relative position of the vehicle 1 with respect to the obstacle, it is possible to avoid contact with the obstacle while maintaining the reference turning radius.

Next, with reference to FIG. 4, the steering angle distribution control when avoiding the above-mentioned obstacle on the outside of the turn will be further explained.
The steering control device 7 starts contact avoidance support control at time t0, which is a predetermined interval before the obstacle on the outside of the turn, and changes the steering angle of the front wheels 2, 2 to the steering angle of the steering wheel 4 from time t0 to time t1. The corresponding steering angle is returned to the neutral position, and the steering angles of the rear wheels 3, 3 are steered from the neutral to the opposite phase.

In other words, the steering control device 7 decreases the steering angle of the front wheels 2, 2 from time t0 to time t1, and makes the steering angle of the rear wheels 3, 3 in opposite phase to the steering angle of the front wheels 2, 2. By determining the front wheel steering command and the rear wheel steering command so as to increase the front wheel steering command, the distribution of the steering angles of the front and rear wheels is changed from the standard distribution.
Thereby, while maintaining the reference turning radius, the outer turning radius of the front end of the vehicle is reduced to a turning radius that does not contact the obstacle, in preparation for the vehicle 1 reaching the obstacle.

Next, when the front end of the vehicle 1 reaches the obstacle, the steering control device 7 controls the front wheels 2 to 2 as the relative position of the vehicle 1 with respect to the obstacle shifts from the front of the vehicle 1 to the rear from time t1 to time t2. , 2 from near the neutral position toward the inside of the turn, and the steering angles of the rear wheels 3, 3 from the opposite phase back toward the neutral position to maintain the standard turning radius of vehicle 1. Contact with obstacles is avoided by moving the position of the minimum turning radius on the outside of the turn from the front end of the vehicle 1 to the rear end.
Then, when the steering control device 7 returns to the standard distribution state in which the outer rear end of the vehicle 1 turns around the outermost circumference, at time t3, the steering control device 7 performs normal control to steer the front wheels 2 according to the steering angle of the steering wheel 4 ( Return to standard allocation).

Next, a description will be given of a process for changing steering angle distribution when avoiding an obstacle on the inside of a turn.
FIG. 7 is a state diagram showing how the steering angles of the front and rear wheels change when a steering angle distribution change process is performed to avoid an obstacle on the inside of a turn.
Further, FIG. 8 is a time chart showing changes in the steering angle and the turning radius when the steering angle distribution changing process for avoiding an obstacle on the inside of the turning is performed.

As shown in Fig. 5, during normal cornering with the front wheels 2, 2 steered and the rear wheels 3, 3 in the neutral position, in other words, during steering based on the standard distribution, the inside of the rear end of the vehicle body is It will turn on the innermost side (innermost circumference).
Here, when the steering control device 7 detects an obstacle on the inside of the turn in front of the vehicle 1, the steering control device 7 detects that the obstacle is located at the innermost periphery of the travel trajectory of the vehicle 1, that is, on the inside of the rear end of the vehicle 1 in the turning trajectory ( It is located on the outside of the turn relative to Rin1) in FIG. 7, and it is determined whether or not the inside rear end of the vehicle 1 will come into contact with an obstacle if the vehicle 1 continues to turn.

Furthermore, when the steering control device 7 predicts that the inside rear end of the vehicle 1 will come into contact with an obstacle, it is possible to avoid the obstacle by controlling the steering angle distribution to be changed while maintaining the reference turning radius. Whether this is the case is determined based on the turning radius of the innermost circumference of the vehicle (Rin2 in FIG. 7) at which the obstacle can be avoided, in other words, the distance from the turning center of the vehicle 1 to the outside of the obstacle.
Then, if it is possible to avoid the obstacle while maintaining the standard turning radius, the steering control device 7 changes the distribution of the steering angle of the front wheels 2, 2 and the steering angle of the rear wheels 3, 3 from the standard distribution. A command is output to the front wheel steering device 5 and the rear wheel steering device 6.

When the front wheels 2, 2 are steered and the rear wheels 3, 3 are placed in the neutral position, the turning center of the vehicle 1 is on the extension line of the axle of the rear wheels 3, 3, as shown in Fig. 5, and the turning The inside of the rear end of the vehicle closest to the center will turn the most inside (innermost circumference).
In addition, when the steering angle of the front wheels 2, 2 is set to the neutral position and the rear wheels 3, 3 are steered in opposite phases, the turning center of the vehicle 1 is an extension of the axle of the front wheels 2, 2, as shown in FIG. The inside of the front end of the vehicle body closest to the turning center will turn on the inside line (innermost circumference).

In other words, even though the inside of the rear end of the vehicle will come into contact with an obstacle on the inside of the turn in the standard steering angle distribution state shown in FIG. 5, if the steering angle distribution state is changed in advance to the steering angle distribution state shown in FIG. The inside of the front end of the vehicle will come into contact with an obstacle on the inside of the turn.
On the other hand, when the front wheels 2, 2 and the rear wheels 3, 3 are steered by the same steering angle in opposite phases, as shown in FIG. The inside of the central part of the vehicle 1 turns on the innermost (innermost) line on the extension line of the direction, but the innermost turning radius (Rin2 in Fig. 7) at this time is as shown in Fig. 5. This is larger than in the standard steering angle distribution state and the steering angle distribution state shown in FIG.

Therefore, when an obstacle exists on the inside of the turn of the vehicle 1, the steering control device 7 changes the steering angle distribution between the front and rear wheels, for example, by changing the front wheels 2, 2 and the rear wheels 3, 3 by the same steering angle in opposite phases. By changing the steering distribution, the innermost turning radius of the travel trajectory of the vehicle 1 is expanded while maintaining the reference turning radius, and the inside of the vehicle 1 is prevented from coming into contact with an obstacle.
The steering angle control in the above-mentioned support control will be explained in detail below with reference to FIG. 8.

The steering control device 7 starts contact avoidance support control at time t0, which is a predetermined interval before the obstacle, and controls the steering angle of the front wheels 2, 2 according to the steering angle of the steering wheel 4 from time t0 to time t1. At the same time, the steering angle of the rear wheels 3, 3 is steered from neutral to the opposite phase to the steering angle of the front wheels 2, 2, so that the steering angles of the front and rear wheels are made to be approximately the same angle and in opposite phase.
In other words, the steering control device 7 changes the steering angle distribution between the front and rear wheels from the reference distribution from time t0 to time t1.

As a result, the innermost turning radius of the vehicle 1 is increased to the outside of the obstacle (Rin2 in FIG. 7) at time t1 while maintaining the reference turning radius.
In other words, between time t0 and time t1 in FIG. A front wheel steering command and a rear wheel steering command are obtained so as to increase the steering angle in a phase opposite to the steering angle of the front wheels 2, 2.

Next, when the relative position of the obstacle moves from the center of the vehicle 1 to the rear end and the vehicle 1 passes the obstacle (time t2), the steering control device 7 increases the steering angle of the front wheels 2, 2, and The steering angle of the rear wheels 3, 3 is decreased and the control returns to normal control (standard distribution) in which the front wheels 2, 2 are steered according to the steering angle of the steering wheel 4 (time t3).
In other words, the steering control device 7 controls the rear wheels 3, 3 as the relative position of the vehicle 1 with respect to the obstacle ahead moves from the center of the vehicle 1 to the rear between time t1 and time t2 in FIG. A front wheel steering command and a rear wheel steering command are determined so that the steering angle (absolute value of the steering angle) of the front wheels 2, 2 becomes larger than the steering angle (absolute value of the steering angle).

As described above, the steering control device 7 uses the contact avoidance support control that changes the steering angle distribution to avoid contact with an obstacle while maintaining the reference turning radius. It is possible to prevent the behavior of the vehicle 1 from becoming a behavior that has no correlation with the driver's operation of the steering wheel 4, and it is possible to suppress the driver's discomfort.
In other words, if the turning radius of the reference position of the vehicle 1 changes due to steering control to avoid contact with an obstacle, the driver may feel that vehicle behavior is occurring that has no correlation with the operation of the steering wheel 4. There is a possibility that you will feel it.
On the other hand, if the turning radius of the reference position of the vehicle 1 can be maintained even if the steering angle is automatically controlled to avoid obstacles, the driver will be less likely to notice changes in the behavior of the vehicle 1, and the driver's discomfort will be suppressed. Support control for contact avoidance can be implemented.

FIG. 10 is a flowchart showing the procedure of contact avoidance support control.
The steering control device 7 first acquires the driver's driving operation information such as the steering angle of the steering wheel 4 in step S101.

In step S102, the steering control device 7 acquires the position information of the obstacle based on the recognition of the obstacle by the external world recognition device 8.
In step S103, the steering control device 7 determines the vehicle turning radius, including the reference turning radius according to the steering angle of the steering wheel 4, the basic steering angles of the front and rear wheels, and the outermost turning radius and the innermost turning radius of the vehicle 1. Calculate the control amount (physical quantity).

In step S104, the steering control device 7 determines whether there is a possibility that the vehicle 1 will come into contact with an obstacle detected in front of the vehicle 1.
Specifically, the steering control device 7 determines the contact turning distance corresponding to the distance from the turning center of the vehicle 1 to the obstacle in standard front and rear wheel steering distribution (standard distribution) based on the relative position of the obstacle with respect to the vehicle 1. Find the radius.

Then, if the contact turning radius exists between the outermost turning radius (Rout1 in FIG. 3) and the innermost turning radius (Rin1 in FIG. 7) obtained in step S103, turning radius ≦contact turning radius ≦outermost turning radius), it is determined that there is a possibility that the vehicle 1 will come into contact with an obstacle.
On the other hand, if the contact turning radius is larger than the outermost turning radius or the contact turning radius is smaller than the innermost turning radius (innermost turning radius > contact turning radius or contact turning radius > outermost turning radius), it is determined that there is no possibility that the vehicle 1 will come into contact with an obstacle.
That is, the steering control device 7 determines whether there is a possibility of contact based on whether or not an obstacle exists on the predicted future turning trajectory.

Then, the steering control device 7 proceeds from step S105 to step S106 when there is a possibility that the vehicle 1 will come into contact with an obstacle, and from step S105 to step S106 when there is no possibility that the vehicle 1 will come into contact with an obstacle. The process bypasses step S109 and proceeds to step S110.
In step S106, the steering control device 7 changes the steering angle distribution from maintaining the reference turning radius to the innermost turning radius or outermost turning radius that allows the vehicle 1 to avoid contact with obstacles. Determine whether it can be changed.

Based on the reference turning radius obtained in step S103, the steering control device 7 determines the minimum outermost turning radius and the maximum innermost turning radius that are achievable while maintaining the reference turning radius, and calculates the minimum outermost turning radius that is achievable while maintaining the reference turning radius. By comparing the turning radius and the maximum innermost turning radius with the contact turning radius, it is determined whether the vehicle 1 can avoid contact with the obstacle.
In other words, if the contact turning radius is smaller than the maximum innermost turning radius (contact turning radius < the maximum innermost turning radius), the steering control device 7 uses the contact avoidance support control to determine the reference position of the vehicle 1. It is determined that contact with obstacles on the inner side of the turn can be avoided by expanding the innermost turning radius while maintaining the turning radius.

In addition, if the contact turning radius is larger than the minimum outermost turning radius (contact turning radius>minimum outermost turning radius), the steering control device 7 performs contact avoidance support control to control the reference turning radius at the reference position of the vehicle 1. It is determined that contact with obstacles on the outside of the turn can be avoided by reducing the outermost turning radius while maintaining .
In addition, the steering control device 7 determines whether the contact turning radius is greater than or equal to the maximum innermost turning radius (contact turning radius ≧ the largest innermost turning radius), or the contact turning radius is less than or equal to the minimum outermost turning radius. If (contact turning radius≦minimum outermost turning radius), it is determined that contact with the obstacle cannot be avoided with steering control that maintains the reference turning radius at the reference position of the vehicle 1.

In the next step S107, the steering control device 7 switches the steering angle calculation process for contact avoidance based on the determination result in step S106.
That is, if the steering control device 7 determines in step S106 that it is possible to avoid contact while maintaining the reference turning radius, the process proceeds to step S108, and determines whether to expand the innermost turning radius while maintaining the reference turning radius. Alternatively, the steering angle is calculated to reduce the outermost turning radius.
As explained with reference to FIGS. 3 to 9, the steering angle calculation in step S108 is performed depending on whether to avoid an obstacle on the outside of the turn or an obstacle on the outside of the turn, and maintains the reference turning radius. By changing the front-rear distribution of the steering angle in this state, the innermost turning radius can be expanded or the outermost turning radius can be reduced.

On the other hand, if the steering control device 7 determines in step S106 that it is not possible to avoid contact while maintaining the reference turning radius, the process proceeds to step S109, and without maintaining the reference turning radius at the reference position of the vehicle 1, A steering angle is calculated to guide the vehicle 1 to a route that avoids contact with obstacles.
Note that when performing the steering angle calculation processing in step S109, the steering control device 7 calculates the steering angle at the reference position of the vehicle 1, unlike the basic control in which contact is avoided while maintaining the reference turning radius at the reference position of the vehicle 1. It is possible to give a warning via screen display, audio, etc. that steering control that may change the turning radius is to be performed.

Furthermore, when performing the steering angle calculation process in step S109, the steering control device 7 outputs a braking/driving control command to the braking/driving device of the vehicle 1 to avoid the vehicle 1 coming into contact with an obstacle. be able to.
In step S110, the steering control device 7 outputs a front wheel steering command to the front wheel steering device 5 and outputs a rear wheel steering command based on the target steering angles of the front and rear wheels obtained in each step of step S103, step S108, and step S109. It is output to the rear wheel steering device 6 to perform front and rear wheel steering control.

The technical ideas described in the above embodiments can be used in combination as appropriate, as long as there is no contradiction.
Further, although the content of the present invention has been specifically explained with reference to preferred embodiments, it is obvious that those skilled in the art can make various modifications based on the basic technical idea and teachings of the present invention. It is.

For example, the steering angle distribution of the front and rear wheels, which is changed from the standard distribution in order to avoid contact between the vehicle 1 and an obstacle, as shown in FIGS. This is a value that can be set.
Further, the steering control device 7 can perform contact avoidance support control on the condition that the vehicle speed is in a predetermined low speed range.
Further, front and rear wheel steering control that changes the distribution of the front wheel steering angle and the rear wheel steering angle with respect to the standard distribution while maintaining the standard turning radius based on the external world information of the vehicle 1, for example, It can be applied to assist systems, etc., and is not limited to obstacle avoidance.

DESCRIPTION OF SYMBOLS 1... Vehicle, 2, 2... Front wheels, 3, 3... Rear wheels, 4... Steering wheel, 5... Front wheel steering device, 6... Rear wheel steering device, 7... Steering control device, 8... External world recognition device (external world recognition unit) )

Claims (9)

A control that performs calculations based on the input information and outputs the calculated results to a front wheel steering device that controls the steering angle of the front wheels of the vehicle and a rear wheel steering device that controls the steering angle of the rear wheels of the vehicle. A steering control device comprising:
The control section includes:
determining a physical quantity related to a reference turning radius at a reference position preset for the vehicle according to the obtained steering angle of the steering wheel;
Determining a standard distribution of the steering angle of the front wheels and the steering angle of the rear wheels based on the physical quantity related to the standard turning radius,
Among the external world information of the vehicle acquired by the external world recognition unit, information on the relative position of the vehicle with respect to an obstacle in front of the vehicle is acquired;
Based on the relative position information, a front wheel steering command and a rear wheel steering command are provided to change the distribution of the front wheel steering angle and the rear wheel steering angle with respect to the standard distribution while maintaining the standard turning radius. Find the wheel steering command,
configured to output the front wheel steering command to the front wheel steering device and output the rear wheel steering command to the rear wheel steering device,
When information regarding the obstacle on the outside of the turning of the vehicle is obtained, the steering angle of the front wheels is decreased with respect to the reference distribution, and the steering angle of the rear wheels is set in reverse phase with respect to the steering angle of the front wheels. increase,
As the relative position moves from the front to the rear of the vehicle, the steering angle of the front wheels increases relative to the steering angle of the rear wheels;
determining the front wheel steering command and the rear wheel steering command;
Steering control device. A control that performs calculations based on the input information and outputs the calculated results to a front wheel steering device that controls the steering angle of the front wheels of the vehicle and a rear wheel steering device that controls the steering angle of the rear wheels of the vehicle. A steering control device comprising:
The control section includes:
determining a physical quantity related to a reference turning radius at a reference position preset for the vehicle according to the obtained steering angle of the steering wheel;
Determining a standard distribution of the steering angle of the front wheels and the steering angle of the rear wheels based on the physical quantity related to the standard turning radius,
Among the external world information of the vehicle acquired by the external world recognition unit, information on the relative position of the vehicle with respect to an obstacle in front of the vehicle is acquired;
Based on the relative position information, a front wheel steering command and a rear wheel steering command are provided to change the distribution of the front wheel steering angle and the rear wheel steering angle with respect to the standard distribution while maintaining the standard turning radius. Find the wheel steering command,
configured to output the front wheel steering command to the front wheel steering device and output the rear wheel steering command to the rear wheel steering device,
When information regarding the obstacle is acquired on the inside of the turn of the vehicle, the steering angle of the front wheels is decreased with respect to the reference distribution, and the steering angle of the rear wheels is set in reverse phase with respect to the steering angle of the front wheels. increase,
As the relative position moves from the center to the rear of the vehicle, the steering angle of the front wheels increases relative to the steering angle of the rear wheels;
determining the front wheel steering command and the rear wheel steering command;
Steering control device. A control that performs calculations based on the input information and outputs the calculated results to a front wheel steering device that controls the steering angle of the front wheels of the vehicle and a rear wheel steering device that controls the steering angle of the rear wheels of the vehicle. A steering control device comprising:
The control section includes:
determining a physical quantity related to a reference turning radius at a reference position preset for the vehicle according to the obtained steering angle of the steering wheel;
Determining a standard distribution of the steering angle of the front wheels and the steering angle of the rear wheels based on the physical quantity related to the standard turning radius,
Among the external world information of the vehicle acquired by the external world recognition unit, information on the relative position of the vehicle with respect to an obstacle in front of the vehicle is acquired;
If an obstacle exists on the inside of the turning of the vehicle, the distribution of the steering angle of the front wheels and the steering angle of the rear wheels is changed with respect to the standard distribution, and the vehicle runs while maintaining the standard turning radius. determining a front wheel steering command and a rear wheel steering command for expanding the innermost turning radius of the trajectory to prevent contact between the vehicle and an obstacle;
If an obstacle exists on the outside of the turning radius of the vehicle, the distribution of the steering angle of the front wheels and the steering angle of the rear wheels is changed with respect to the standard distribution, and the vehicle runs while maintaining the standard turning radius. Determining the front wheel steering command and the rear wheel steering command for reducing the outermost turning radius of the trajectory to prevent contact between the vehicle and an obstacle;
outputting the front wheel steering command to the front wheel steering device, and outputting the rear wheel steering command to the rear wheel steering device;
Steering control device. A steering control method executed by a steering control device mounted on a vehicle, comprising: a front wheel steering device that controls a steering angle of a front wheel of a vehicle; and a rear wheel steering device that controls a steering angle of a rear wheel of the vehicle. ,
determining a physical quantity related to a reference turning radius at a reference position preset for the vehicle according to the obtained steering angle of the steering wheel;
determining a standard distribution of the steering angle of the front wheels and the steering angle of the rear wheels based on the physical quantity related to the standard turning radius;
A step of acquiring information on a relative position of the vehicle with respect to an obstacle in front of the vehicle from among the external world information of the vehicle acquired by the external world recognition unit;
Based on the relative position information, a front wheel steering command and a rear wheel steering command are provided to change the distribution of the front wheel steering angle and the rear wheel steering angle with respect to the standard distribution while maintaining the standard turning radius. a step of determining a wheel steering command;
outputting the front wheel steering command to the front wheel steering device and outputting the rear wheel steering command to the rear wheel steering device;
including;
The step of obtaining the front wheel steering command and the rear wheel steering command includes:
When information regarding the obstacle on the outside of the turning of the vehicle is obtained, the steering angle of the front wheels is decreased with respect to the reference distribution, and the steering angle of the rear wheels is set in reverse phase with respect to the steering angle of the front wheels. increase,
As the relative position moves from the front to the rear of the vehicle, the steering angle of the front wheels increases relative to the steering angle of the rear wheels;
determining the front wheel steering command and the rear wheel steering command;
Steering control method. A steering control method executed by a steering control device mounted on a vehicle, comprising: a front wheel steering device that controls a steering angle of a front wheel of a vehicle; and a rear wheel steering device that controls a steering angle of a rear wheel of the vehicle. ,
determining a physical quantity related to a reference turning radius at a reference position preset for the vehicle according to the obtained steering angle of the steering wheel;
determining a standard distribution of the steering angle of the front wheels and the steering angle of the rear wheels based on the physical quantity related to the standard turning radius;
A step of acquiring information on a relative position of the vehicle with respect to an obstacle in front of the vehicle from among the external world information of the vehicle acquired by the external world recognition unit;
Based on the relative position information, a front wheel steering command and a rear wheel steering command are provided to change the distribution of the front wheel steering angle and the rear wheel steering angle with respect to the standard distribution while maintaining the standard turning radius. a step of determining a wheel steering command;
outputting the front wheel steering command to the front wheel steering device and outputting the rear wheel steering command to the rear wheel steering device;
including;
The step of obtaining the front wheel steering command and the rear wheel steering command includes:
When information regarding the obstacle is acquired on the inside of the turn of the vehicle, the steering angle of the front wheels is decreased with respect to the reference distribution, and the steering angle of the rear wheels is set in reverse phase with respect to the steering angle of the front wheels. increase,
As the relative position moves from the center to the rear of the vehicle, the steering angle of the front wheels increases relative to the steering angle of the rear wheels;
determining the front wheel steering command and the rear wheel steering command;
Steering control method. A steering control method executed by a steering control device mounted on a vehicle, comprising: a front wheel steering device that controls a steering angle of a front wheel of a vehicle; and a rear wheel steering device that controls a steering angle of a rear wheel of the vehicle. ,
determining a physical quantity related to a reference turning radius at a reference position preset for the vehicle according to the obtained steering angle of the steering wheel;
determining a standard distribution of the steering angle of the front wheels and the steering angle of the rear wheels based on the physical quantity related to the standard turning radius;
A step of acquiring information on a relative position of the vehicle with respect to an obstacle in front of the vehicle from among the external world information of the vehicle acquired by the external world recognition unit;
If an obstacle exists on the inside of the turning of the vehicle, the distribution of the steering angle of the front wheels and the steering angle of the rear wheels is changed with respect to the standard distribution, and the vehicle runs while maintaining the standard turning radius. obtaining a front wheel steering command and a rear wheel steering command for expanding the innermost turning radius of the trajectory to prevent contact between the vehicle and an obstacle;
If an obstacle exists on the outside of the turning radius of the vehicle, the distribution of the steering angle of the front wheels and the steering angle of the rear wheels is changed with respect to the standard distribution, and the vehicle runs while maintaining the standard turning radius. obtaining the front wheel steering command and the rear wheel steering command for reducing the outermost turning radius of the trajectory to prevent contact between the vehicle and an obstacle;
outputting the front wheel steering command to the front wheel steering device and outputting the rear wheel steering command to the rear wheel steering device;
A steering control method, including: an external world recognition unit that acquires external world information of the vehicle;
A control section,
determining a physical quantity related to a reference turning radius at a reference position preset for the vehicle according to the obtained steering angle of the steering wheel;
determining a standard distribution of a steering angle of a front wheel of the vehicle and a steering angle of a rear wheel of the vehicle based on a physical quantity related to the standard turning radius;
Among the external world information of the vehicle acquired by the external world recognition unit, information on the relative position of the vehicle with respect to an obstacle in front of the vehicle is acquired;
Based on the relative position information, a front wheel steering command and a rear wheel steering command are provided to change the distribution of the front wheel steering angle and the rear wheel steering angle with respect to the standard distribution while maintaining the standard turning radius. Find the wheel steering command,
configured to output the front wheel steering command and the rear wheel steering command,
When information regarding the obstacle on the outside of the turning of the vehicle is obtained, the steering angle of the front wheels is decreased with respect to the reference distribution, and the steering angle of the rear wheels is set in reverse phase with respect to the steering angle of the front wheels. increase,
As the relative position moves from the front to the rear of the vehicle, the steering angle of the front wheels increases relative to the steering angle of the rear wheels;
determining the front wheel steering command and the rear wheel steering command;
the control section;
a front wheel steering device that acquires the front wheel steering command output from the control unit;
a rear wheel steering device that acquires the rear wheel steering command output from the control unit;
A steering control system equipped with an external world recognition unit that acquires external world information of the vehicle;
A control section,
determining a physical quantity related to a reference turning radius at a reference position preset for the vehicle according to the obtained steering angle of the steering wheel;
determining a standard distribution of a steering angle of a front wheel of the vehicle and a steering angle of a rear wheel of the vehicle based on a physical quantity related to the standard turning radius;
Among the external world information of the vehicle acquired by the external world recognition unit, information on the relative position of the vehicle with respect to an obstacle in front of the vehicle is acquired;
Based on the relative position information, a front wheel steering command and a rear wheel steering command are provided to change the distribution of the front wheel steering angle and the rear wheel steering angle with respect to the standard distribution while maintaining the standard turning radius. Find the wheel steering command,
configured to output the front wheel steering command and the rear wheel steering command,
When information regarding the obstacle is acquired on the inside of the turn of the vehicle, the steering angle of the front wheels is decreased with respect to the reference distribution, and the steering angle of the rear wheels is set in reverse phase with respect to the steering angle of the front wheels. increase,
As the relative position moves from the center to the rear of the vehicle, the steering angle of the front wheels increases relative to the steering angle of the rear wheels;
determining the front wheel steering command and the rear wheel steering command;
the control section;
a front wheel steering device that acquires the front wheel steering command output from the control unit;
a rear wheel steering device that acquires the rear wheel steering command output from the control unit;
A steering control system equipped with an external world recognition unit that acquires external world information of the vehicle;
A control section,
determining a physical quantity related to a reference turning radius at a reference position preset for the vehicle according to the obtained steering angle of the steering wheel;
determining a standard distribution of a steering angle of a front wheel of the vehicle and a steering angle of a rear wheel of the vehicle based on a physical quantity related to the standard turning radius;
Among the external world information of the vehicle acquired by the external world recognition unit, information on the relative position of the vehicle with respect to an obstacle in front of the vehicle is acquired;
If an obstacle exists on the inside of the turning of the vehicle, the distribution of the steering angle of the front wheels and the steering angle of the rear wheels is changed with respect to the standard distribution, and the vehicle runs while maintaining the standard turning radius. determining a front wheel steering command and a rear wheel steering command for expanding the innermost turning radius of the trajectory to prevent contact between the vehicle and an obstacle;
If an obstacle exists on the outside of the turning radius of the vehicle, the distribution of the steering angle of the front wheels and the steering angle of the rear wheels is changed with respect to the standard distribution, and the vehicle runs while maintaining the standard turning radius. Determining the front wheel steering command and the rear wheel steering command for reducing the outermost turning radius of the trajectory to prevent contact between the vehicle and an obstacle;
outputting the front wheel steering command and the rear wheel steering command;
the control section;
a front wheel steering device that acquires the front wheel steering command output from the control unit;
a rear wheel steering device that acquires the rear wheel steering command output from the control unit;
A steering control system equipped with