JP7347450B2 - Steering control device - Google Patents

Description

The present invention relates to a steering control device.

Automatic steering of a vehicle includes steering control that allows the vehicle to follow the vehicle in front, and steering control that maintains the vehicle in its driving lane. In this type of steering control, a steering command angle is calculated based on the driving situation (for example, the positional relationship and speed difference between the host vehicle and the vehicle in front), and the actual steering angle is controlled based on the calculated steering command angle. be done.

Japanese Patent Application Publication No. 10-297516

By the way, when it is assumed that the host vehicle will stop, there is a possibility that an incorrect steering angle will be controlled. For example, if the steering instruction angle is calculated based on the positional relationship between the own vehicle and the vehicle in front, an incorrect steering instruction angle will be calculated and the steering will be controlled even immediately after the own vehicle has stopped.

Therefore, the present invention has been made in view of these points, and an object of the present invention is to appropriately steer a vehicle in a situation where it is assumed that the vehicle will stop.

In one aspect of the present invention, there is provided an instruction angle calculation unit that calculates a steering instruction angle when automatically steering a vehicle based on driving conditions, and a vehicle speed determination unit that determines whether the vehicle speed of the vehicle is smaller than a threshold value. and when it is determined that the vehicle speed is smaller than the threshold value, a limit value setting section that sets a limit value of the steering angular velocity and the indicated steering angle calculated by the indicated angle calculation section are set such that the steering angular velocity is less than the limit value A steering control device is provided, comprising: a steering adjustment section that adjusts the limit value so that the limit value is smaller than the limit value set by a value setting section.

Further, the limit value setting unit may set the limit value to be smaller as the time elapsed since the vehicle speed was determined to be smaller than the threshold value becomes longer.

Further, the steering adjustment section may adjust the steering instruction angle calculated by the instruction angle calculation section while the vehicle is stopped so that the steering angular velocity becomes smaller than the limit value.

Furthermore, when it is determined that the vehicle speed is equal to or higher than the threshold value, the limit value setting unit may set the limit values of the steering angular velocity and the steering angle according to the magnitude of the vehicle speed.

According to the present invention, there is an effect that the vehicle can be appropriately steered in a situation where the vehicle is assumed to be stopped.

FIG. 1 is a schematic diagram for explaining the configuration of a vehicle 1 equipped with a steering control device according to one embodiment. FIG. 3 is a schematic diagram for explaining limit values. 3 is a flowchart for explaining the flow of steering control processing of the vehicle 1. FIG.

<Configuration of steering control device>
The configuration of a steering control device according to one embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic diagram for explaining the configuration of a vehicle 1 equipped with a steering control device according to one embodiment. Vehicle 1 is, for example, a truck. The vehicle 1 is capable of automatic driving, and includes, for example, steering control to follow a vehicle in front and steering control to maintain a driving lane. As shown in FIG. 1, the vehicle 1 includes a surroundings detection device 2, a vehicle speed detection device 4, a motor 6, and a control device 10 that is a steering control device.

The surroundings detection device 2 detects the surroundings of the vehicle 1 while it is running. The surroundings detection device 2 includes a camera here, and images the lane in front of the vehicle 1 and the preceding vehicle. The surroundings detection device 2 may include a radar in addition to a camera. The surroundings detection device 2 outputs the detection results to the control device 10.

Vehicle speed detection device 4 detects the vehicle speed of vehicle 1, which is the own vehicle. Further, the vehicle speed detection device 4 detects the vehicle speeds of vehicles around the vehicle 1 (for example, a vehicle running in front of the vehicle 1). Vehicle speed detection device 4 outputs the detection result to control device 10 .

The motor 6 is provided, for example, on the steering shaft of the vehicle 1. The motor 6 is rotated by electric power supplied from the control device 10 to apply torque to the steering shaft to perform a steering operation. The motor 6 has a steering assist function when the vehicle 1 is automatically steered.

The control device 10 controls the running of the vehicle 1. The control device 10 performs steering control for automatically steering the vehicle 1. For example, the control device 10 performs steering control for driving the vehicle to follow a vehicle in front, and steering control for keeping the vehicle in the driving lane. At this time, the control device 10 calculates the steering instruction angle based on the driving situation of the vehicle 1, and controls the actual steering angle based on the calculated steering instruction angle.

By the way, when it is assumed that the own vehicle 1 will stop, there is a possibility that an incorrect steering angle will be controlled. For example, if the steering instruction angle is calculated based on the positional relationship between the vehicle 1 and the vehicle in front, an incorrect steering instruction angle will be calculated and the steering will be controlled even immediately after the vehicle 1 has stopped.
On the other hand, the control device 10 of the present embodiment sets a limit value of the steering angular velocity when it is determined that the vehicle speed of the vehicle 1 is smaller than the threshold value, although the details will be described later. Then, the control device 10 adjusts the calculated steering instruction angle so that the steering angular velocity becomes smaller than the set limit value (filter function). Thereby, even if the steering instruction angle is erroneously determined while the vehicle 1 is stopped, the steering instruction angle can be adjusted to a small value using the limit value, so that steering while the vehicle 1 is stopped can be suppressed. Further, by adjusting the steering instruction angle to a small value, it is possible to suppress loss of followability even if the vehicle 1 continues to travel at a speed below the threshold value.

The control device 10 includes a storage section 12 and a control section 14, as shown in FIG.
The storage unit 12 includes, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit 12 stores programs and various data for the control unit 14 to execute. For example, the storage unit 12 stores a vehicle speed threshold for setting a steering angle limit value.

The control unit 14 is, for example, a CPU (Central Processing Unit). The control unit 14 functions as an indicated angle calculation unit 142, a vehicle speed determination unit 143, a limit value setting unit 144, a steering adjustment unit 145, and a steering control unit 146 by executing a program stored in the storage unit 12.

The instructed angle calculation unit 142 calculates a steering instruction angle when automatically steering the vehicle 1 based on the driving situation. The indicated angle calculating section 142 calculates a steering indicated angle based on the detection result of the surrounding detection device 2. For example, the instruction angle calculation unit 142 calculates a steering instruction angle so that the vehicle maintains the driving lane detected by the surrounding detection device 2. Further, the indicated angle calculation unit 142 calculates a steering indicated angle so as to follow the vehicle in front detected by the surrounding detection device 2.

Vehicle speed determination unit 143 determines whether the vehicle speed of vehicle 1 is smaller than a threshold value. The vehicle speed determination unit 143 determines whether the vehicle speed detected by the vehicle speed detection device 4 is smaller than a threshold value. The threshold value is a value that can be assumed to cause the vehicle 1 to stop, and is 0.5 km/h as an example here, but is not limited to this.

The limit value setting section 144 sets a limit value for adjusting the steering instruction angle calculated by the instruction angle calculating section 142. The limit value setting section 144 sets a limit value based on the determination result of the vehicle speed determining section 143. For example, the limit value setting unit 144 sets a limit value for the steering angular velocity when the vehicle speed determining unit 143 determines that the vehicle speed is smaller than the threshold value. That is, the limit value setting unit 144 sets the limit value of the steering angular velocity when the vehicle 1 is assumed to stop (immediately before stopping).

When the vehicle speed determining section 143 determines that the vehicle speed is equal to or higher than the threshold value, the limit value setting section 144 sets the limit values of the steering angular velocity and the steering angle according to the magnitude of the vehicle speed. That is, when the vehicle 1 is traveling while keeping the driving lane or when the vehicle 1 is traveling following a vehicle in front, the limit value setting unit 144 adjusts the steering angular velocity according to the magnitude of the vehicle speed. and set the steering angle.

The limit value setting unit 144 may change the size of the limit value without fixing it when it is determined that the vehicle speed is smaller than the threshold value. For example, the limit value setting unit 144 sets the limit value to be smaller as the time elapsed since the vehicle speed was determined to be smaller than the threshold value becomes longer. Therefore, the limit value while the vehicle 1 is stopped is smaller than the limit value immediately before the vehicle 1 stops.

FIG. 2 is a schematic diagram for explaining limit values. The horizontal axis of the graph in FIG. 2 indicates the elapsed time since the vehicle speed was determined to be smaller than the threshold value, and the vertical axis indicates the magnitude of the limit value. Here, it is assumed that the magnitude of the limit value set immediately after it is determined that the vehicle speed is smaller than the threshold value is the value A1. The size of the limit value becomes smaller as the elapsed time becomes longer. The magnitude of the limit value when time t1 has elapsed is value A2. Time t1 is the time when the vehicle is assumed to have stopped. In this way, the limit value setting unit 144 gradually sets the limit value smaller until the time t1 has elapsed. Note that the limit value setting unit 144 may set the limit value to be smaller in steps.

In FIG. 2, even after time t1 has elapsed, the magnitude of the limit value is greater than 0 (that is, even if the vehicle 1 is stopped, the limit value is not 0). By setting the limit value to be larger than 0 in this way, it is possible to suppress sudden steering even if the vehicle in front starts suddenly.

The steering adjustment section 145 adjusts the steering instruction angle calculated by the instruction angle calculation section 142. The steering adjustment section 145 adjusts the steering instruction angle calculated by the instruction angle calculation section 142 so that the steering angular velocity becomes smaller than the limit value set by the limit value setting section 144. Since the steering angular velocity is determined by differentiating the steering instruction angle, the magnitude of the steering instruction angle can be adjusted using the limit value of the steering angular velocity.

The steering adjustment unit 145 may adjust the steering instruction angle calculated by the instruction angle calculation unit 142 not only before the vehicle 1 stops but also while the vehicle 1 is stopped so that the steering angular velocity becomes smaller than the limit value. good. For example, even if the indicated steering angle calculating section 142 incorrectly calculates the steering indicated angle based on the positional relationship between the vehicle 1 and the vehicle in front immediately after the vehicle 1 stops, the limit value set by the limit value setting section 144 may be used. The amount of steering can be reduced. Thereby, it is possible to suppress the steering wheel of the vehicle 1 from moving due to the steering control while the vehicle 1 is stopped.

The steering control unit 146 controls the steering of the vehicle 1 by controlling the motor 6. The steering control unit 146 controls the steering of the vehicle 1 based on the steering instruction angle adjusted by the steering adjustment unit 145 using the limit value.

In addition, as described above, if the limit value is set to be smaller as the time that has elapsed since it was determined that the vehicle speed of the vehicle 1 is smaller than the threshold value, the limit value does not change suddenly, so It is possible to suppress sudden changes in the steering amount.
Note that even if the vehicle 1 is traveling at a vehicle speed lower than the threshold value, since the steering instruction angle is adjusted based on the limit value, it is possible to suppress the followability from being impaired.

<Flow of steering control processing>
The flow of the steering control process for the vehicle 1 will be described with reference to FIG. 3.

FIG. 3 is a flowchart for explaining the flow of the steering control process of the vehicle 1. Here, the steering control process when the vehicle 1 stops will be explained. The process shown in FIG. 3 is repeatedly executed at predetermined time intervals.

First, the instruction angle calculation unit 142 calculates a steering instruction angle for automatically steering the vehicle 1 based on the driving situation of the vehicle 1 (step S102). For example, when the vehicle 1 follows the vehicle in front, the indicated angle calculation unit 142 calculates the steering angle so as to follow the travel trajectory of the vehicle in front.

Next, the vehicle speed determination unit 143 determines whether the vehicle speed of the vehicle 1 is smaller than a threshold value (step S104). That is, the vehicle speed determination unit 143 determines whether it is possible to assume that the vehicle 1 will stop. For example, the vehicle speed determination unit 143 determines whether the vehicle speed is smaller than 0.5 km/h.

Next, if it is determined in step S104 that the vehicle speed is smaller than the threshold (Yes), in other words, if it is assumed that the vehicle 1 will stop, the limit value setting unit 144 sets a limit on the steering angular velocity. A value is set (step S106). The limit value setting unit 144 sets a limit value regardless of the speed of the vehicle 1. At this time, the limit value setting unit 144 sets the limit value smaller as the time elapsed since the vehicle speed was determined to be smaller than the threshold value becomes longer (see FIG. 2).

On the other hand, if it is determined in step S104 that the vehicle speed is equal to or higher than the threshold (No), in other words, if it is estimated that the vehicle 1 is traveling, the limit value setting unit 144 sets the vehicle speed to Limit values of the steering angular velocity and steering angle are set according to (step S108). Thereby, a limit value is set according to the driving state.

Next, the steering adjustment unit 145 adjusts the steering instruction angle calculated by the instruction angle calculation unit 142 in step S102 based on the limit value set in step S106 or step S108 (step S110). For example, when it is assumed that the vehicle 1 will stop, the steering adjustment unit 145 adjusts the steering instruction angle calculated by the instruction angle calculation unit 142 so that the steering angular velocity becomes smaller than the limit value set in step S106. do.

<Effects of this embodiment>
The control device 10 of the embodiment described above determines a steering instruction angle when automatically steering the vehicle 1 based on the driving situation of the vehicle 1. When it is determined that the vehicle speed of the vehicle 1 to be automatically steered is smaller than the threshold value, the control device 10 sets a limit value of the steering angular velocity. Then, the control device 10 adjusts the calculated steering instruction angle so that the actual steering angular velocity becomes smaller than the set limit value.
As a result, when the vehicle 1 is assumed to be stationary, the steering command angle is adjusted so that the actual steering angular velocity is smaller than the limit value, so the steering command angle is incorrectly determined. is also adjusted to a smaller value by the limit value. As a result, steering while the vehicle 1 is stopped can be suppressed.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes can be made within the scope of the gist. be. For example, all or part of the device can be functionally or physically distributed and integrated into arbitrary units. In addition, new embodiments created by arbitrary combinations of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiment resulting from the combination have the effects of the original embodiment.

1 Vehicle 10 Control device 142 Indication angle calculation section 143 Vehicle speed determination section 144 Limit value setting section 145 Steering adjustment section

Claims (3)

an instruction angle calculation unit that calculates a steering instruction angle when automatically steering the vehicle so as to follow a vehicle in front ;
a vehicle speed determination unit that determines whether the vehicle speed of the vehicle is smaller than a threshold;
a limit value setting unit that sets a limit value of a steering angular velocity when it is determined that the vehicle speed is smaller than the threshold value when following the vehicle in front ;
a steering adjustment section that adjusts the steering instruction angle calculated by the instruction angle calculation section so that the steering angular velocity becomes smaller than the limit value set by the limit value setting section;
A steering control device comprising: The limit value setting unit sets the limit value to be smaller as the time elapsed since the vehicle speed was determined to be smaller than the threshold value becomes longer.
The steering control device according to claim 1. The steering adjustment section adjusts the steering instruction angle calculated by the instruction angle calculation section while the vehicle is stopped so that the steering angular velocity becomes smaller than the limit value.
The steering control device according to claim 1 or 2.

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