JP7609017B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device, and more particularly to a vehicle control device suitable for use in avoidance assistance.

Patent document 1 discloses a device that generates additional steering torque when the driver performs an evasive maneuver to increase the amount of lateral movement of the vehicle so that the vehicle does not collide with an obstacle.

Special table 2019-533601 publication

In the device disclosed in Patent Document 1, after it is determined that the target amount of lateral movement has been achieved, a steering torque opposite to the avoidance steering torque is applied. This means that there is a risk that the vehicle will move beyond the target amount of lateral movement, which may result in the vehicle departing from the lane.

This disclosure was made in consideration of the above-mentioned problems, and aims to provide a vehicle control device that reliably and smoothly displaces the vehicle's traveling position in the lane width direction to a target position.

The vehicle control device of the present invention is configured to execute steering control in response to the presence of an object to be avoided ahead, so as to steer the vehicle so as to displace the vehicle's running position in the lane width direction to a target running position where a target avoidance amount is achieved. The steering control includes feedback control for making the front and rear axes of the vehicle parallel to the lane travel direction. The feedback control is started in response to the lateral deviation of the vehicle's running position from the target running position becoming equal to or less than a set value.

According to the vehicle control device of the present invention, feedback control in steering control is initiated when the lateral deviation of the vehicle's driving position from the target driving position falls below a set value, so that the vehicle's driving position in the lane width direction can be reliably and smoothly displaced to the target driving position while preventing the vehicle from overshooting the target driving position.

1 is a schematic diagram for explaining the operation of a vehicle whose steering is controlled by a vehicle control device according to an embodiment of the present invention; 4 is a flowchart showing a control flow of steering control by a vehicle control device according to an embodiment of the present invention.

Below, the embodiments of the present invention will be described with reference to the drawings. However, when the numbers, quantities, amounts, ranges, etc. of each element are mentioned in the embodiments shown below, the invention is not limited to the mentioned numbers unless specifically stated or clearly specified in principle. Furthermore, the structures, steps, etc. described in the embodiments shown below are not necessarily essential to the invention unless specifically stated or clearly specified in principle.

A vehicle control device according to an embodiment of the present invention is mounted on a vehicle and assists the driver in driving the vehicle. Driving assistance provided to the vehicle control device includes avoidance assistance for avoiding obstacles. In avoidance assistance, the vehicle control device controls the steering of the vehicle on behalf of the driver. Figure 1 is a schematic diagram for explaining the operation of a vehicle 2 whose steering is controlled by a vehicle control device 10. Below, an overview of steering control for avoidance assistance by the vehicle control device 10 will be explained using Figure 1.

The left-right direction in FIG. 1 corresponds to the lane width direction of the road on which vehicle 2 is traveling, and the up-down direction in FIG. 1 corresponds to the lane travel direction. In the example shown in FIG. 1, the initial traveling position of vehicle 2, i.e., the traveling position in the lane width direction, is LP0. Hereinafter, the initial traveling position LP0 in the lane width direction is referred to as the initial traveling position LP0.

In the example shown in FIG. 1, when a traveling vehicle 2 is at an initial traveling position LP0, the vehicle control device 10 detects an object to be avoided 4 in front of the vehicle 2. There are no limitations on the method of detecting the object to be avoided 4. For example, an object in the vicinity of the vehicle 2 may be detected by a surrounding monitoring sensor such as a camera or LIDAR mounted on the vehicle 2, and it may be determined whether or not the object detected in the vicinity of the vehicle 2 is an object to be avoided based on the size, position, and movement of the object.

Upon detection of an object to be avoided 4 ahead, the vehicle control device 10 moves the vehicle 2 in a direction away from the object to be avoided 4. Specifically, the amount of movement in the lane width direction required to avoid contact with the object to be avoided 4 is calculated as a target amount of avoidance, and the traveling position in the lane width direction at which the target amount of avoidance can be achieved is set as the target traveling position LPt. Then, steering control is executed to steer the vehicle 2 so as to displace the traveling position LP of the vehicle 2 in the lane width direction from the initial traveling position LP0 to the target traveling position LPt.

The vehicle control device 10 steers the vehicle 2 so as to move the vehicle 2 along the ideal driving trajectory TTi. The ideal driving trajectory TTi is a driving trajectory that can reliably and smoothly displace the driving position LP of the vehicle 2 to the target driving position LPt. In order to realize the ideal driving trajectory TTi, feedback control of the yaw angle of the vehicle 2 is required so that the front and rear axes of the vehicle 2 are parallel to the lane travel direction when the vehicle 2 reaches the target driving position LPt. For this reason, the steering control for avoidance assistance performed by the vehicle control device 10 includes feedback control.

However, feedback control does not simply need to be executed. If feedback control is started after the vehicle 2 reaches the target driving position LPt, the vehicle 2 will overshoot the target driving position LPt. Therefore, feedback control must be started before the vehicle 2 reaches the target driving position LPt, but the control results obtained will differ depending on how the control is executed.

For example, one approach is to execute feedback control from the start of steering control. However, in this case, control that attempts to make the front and rear axes of the vehicle 2 parallel to the lane travel direction intervenes immediately after the start of steering control, making it difficult to increase the amount of avoidance, and there is a risk that the vehicle 2 will not be able to avoid the avoidance target 4.

One approach is to start feedback control when a certain amount of time has elapsed since the start of steering control, or when the distance between the target to be avoided 4 and the vehicle 2 falls below a set value. However, if feedback control is started at these times, the steering control for avoidance may be hindered due to errors in the recognition timing and position of the target to be avoided 4 by the vehicle 2's surroundings monitoring sensor.

Another approach is to increase the feedback control gain as the vehicle 2's driving position LP approaches the white line of the lane on the avoidance side. However, in this case, depending on the distance between the target driving position LPt and the white line, there is a risk that the front-rear axis of the vehicle 2 may not be parallel to the lane travel direction.

As described above, if the method of executing feedback control is not appropriate, the vehicle 2 cannot be moved along the ideal driving trajectory TTi. Therefore, the vehicle control device 10 starts feedback control when the lateral deviation of the driving position LP of the vehicle 2 from the target driving position LPt becomes equal to or less than a set value. In other words, in this embodiment, the timing of executing feedback control is determined based on the distance from the target driving position LPt. Note that the set value may be a fixed value or a variable value that is set according to, for example, the vehicle speed.

Figure 2 is a flowchart showing the control flow of steering control by the vehicle control device 10. After starting steering control, in step S1, the vehicle control device 10 calculates the lateral deviation of the driving position LP with respect to the target driving position LPt, and determines whether the lateral deviation is equal to or less than a set value.

If the lateral deviation is determined to be greater than the set value in step S1, step S3 is selected. In step S3, the vehicle control device 10 does not execute feedback control to make the front and rear axes of the vehicle 2 parallel to the lane travel direction. In other words, the vehicle control device 10 continues steering control without feedback control.

After step S3, step S4 is executed. In step S4, the vehicle control device 10 determines whether the vehicle 2 has reached the target driving position LPt and whether the front and rear axes of the vehicle 2 are parallel to the lane travel direction.

While feedback control is not being performed, the determination result in step S4 is negative. The control flow returns to step S1, and the vehicle control device 10 updates the lateral deviation of the driving position LP relative to the target driving position LPt. Then, it is determined whether the updated lateral deviation is equal to or less than a set value. Steps S1, S3, and S4 are repeatedly executed by the vehicle control device 10 until the lateral deviation becomes equal to or less than the set value.

When the lateral deviation of the vehicle 2's driving position LP from the target driving position LPt becomes equal to or less than the set value, step S2 is selected. In step S2, the vehicle control device 10 executes feedback control to make the front and rear axes of the vehicle 2 parallel to the lane travel direction.

After step S3, step S4 is executed. In step S4, the vehicle control device 10 determines whether the vehicle 2 has reached the target driving position LPt and whether the front and rear axes of the vehicle 2 are parallel to the lane travel direction.

Immediately after feedback control begins, the condition of step S4 is not satisfied, and steps S1, S2, and S4 are repeatedly executed by the vehicle control device 10. During this time, feedback control is executed by the vehicle control device 10, and the vehicle 2 approaches the target driving position LPt, while the front-rear axis of the vehicle 2 becomes parallel to the traveling direction of the lane. Eventually, when the vehicle 2 reaches the target driving position LPt and the front-rear axis of the vehicle 2 becomes parallel to the traveling direction of the lane, the steering control ends.

As described above, according to the vehicle control device 10, feedback control is started when the lateral deviation of the driving position LP of the vehicle 2 from the target driving position LPt becomes equal to or less than a set value. This makes it possible to prevent the vehicle 2 from overshooting the target driving position LPt. In addition, since the feedback control does not interfere with the steering control for avoidance, the driving position LP of the vehicle 2 can be reliably and smoothly displaced to the target driving position LPt.

2 Vehicle 4 Avoidance target 10 Vehicle control device LP Travel position LP0 in lane width direction Initial travel position LPt Target travel position TTi Ideal travel trajectory

Claims (1)

The steering control is configured to execute, in response to the presence of an object to be avoided ahead, steering the vehicle so as to displace a traveling position of the vehicle in a lane width direction to a target traveling position at which a target avoidance amount is achieved,
the steering control includes a feedback control for making the front and rear axes of the vehicle parallel to the traveling direction of the lane;
The vehicle control device is characterized in that the feedback control is started when a lateral deviation of the traveling position with respect to the target traveling position becomes equal to or smaller than a set value.

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