WO2022057146A1

WO2022057146A1 - Control method for rear wheel steering in low-speed traveling of vehicle

Info

Publication number: WO2022057146A1
Application number: PCT/CN2020/140631
Authority: WO
Inventors: 单帅; 郝文权; 禹真; 余景龙; 王念强
Original assignee: 中国第一汽车股份有限公司
Priority date: 2020-09-17
Filing date: 2020-12-29
Publication date: 2022-03-24
Also published as: CN112158256A

Abstract

A control method for rear wheel steering in low-speed traveling of a vehicle, being suitable for controlling rear wheel steering when the vehicle speed is less than or equal to 30 Km/h. An around view monitor is linked with a rear wheel steering system; under a specific low-speed forward steering working condition, control of vehicle rear wheel steering is stopped, and a motion trajectory of a rear portion of a vehicle body is kept within a motion trajectory of a front portion of the vehicle body, so as to avoid a collision accident; under a specific low-speed reverse gear steering traveling working condition, a steering angle of rear wheels (2) is controlled to be an extreme angle in a certain direction, so as to facilitate reverse parking.

Description

A method for controlling rear wheel steering when a vehicle is running at low speed

technical field

The invention belongs to the technical field of vehicle rear wheel steering control, and in particular relates to a control method for rear wheel steering when a vehicle runs at low speed.

Background technique

For models with only front wheel steering, the movement trajectory of the rear of the vehicle body is within the movement trajectory of the front of the vehicle body when the vehicle is turned forward.

However, in recent years, more and more high-end models are equipped with rear wheel steering, that is, on the basis of front wheel steering, the rear wheels also cooperate with the front wheels to make specific steering actions. For vehicles equipped with rear-wheel steering, when the vehicle is running at low speeds, the rear wheels rotate in the opposite direction to the front wheels, and when the vehicle is running at high speeds, the rear wheels rotate in the same direction as the front wheels. At the same time, the rear wheel steering will also bring about changes in the driver’s driving habits. For example, when turning forward at a low speed, in order to reduce the turning radius, the rear wheels turn in the opposite direction to the front wheels. At this time, the trajectory of the rear of the vehicle exceeds the front of the vehicle. If there is an obstacle on the side of the vehicle, the obstacle avoidance becomes poor, and collision accidents are prone to occur, or the driver needs extra energy and experience to correct the direction. When the vehicle is driving in reverse gear at low speed (such as reversing into a garage), the rear wheels and front wheels rotate in the opposite direction, but if there is an obstacle behind the vehicle body, the reverse rotation of the rear wheels may not adapt to the ideal reversing route.

SUMMARY OF THE INVENTION

In order to overcome the above problems, the present invention provides a method for controlling the steering of the rear wheels when the vehicle is running at a low speed, which is suitable for controlling the steering of the rear wheels when the vehicle speed is less than or equal to 30Km/h. Controlling the rear wheel steering angle at low speed makes the vehicle's driving route conform to the ideal driving route and fills the gap of rear wheel steering technology in this respect.

A control method for rear wheel steering when a vehicle runs at low speed, comprising the following contents:

When the vehicle is traveling at a speed of ≤30Km/h:

When the gap value between the outer side of the vehicle body and the obstacle is less than or equal to 0.3m, and the front wheel of the vehicle has a turning angle, the rear wheel steering controller controls the steering angle of the rear wheel to 0 degrees; When the gap value between the obstacle and the obstacle is greater than or equal to 0.5mm, the rear wheel steering controller returns to the normal control function of the rear wheel steering;

When driving in reverse at low speed:

When the vehicle is in reverse gear, the rear wheel steering controller controls the steering angle of the rear wheels to 0 degrees. The panoramic surround view system collects the rotation angle signals of the rear wheels at this time, and calculates the reversing route based on the rotation angle signals of the front wheels. The position of the obstacle on the side of the vehicle body on the reversing route, if the rear wheel can avoid the obstacle on the side of the vehicle body when turning at a limit angle in a certain direction, the rear wheel steering controller will control the rear wheel of the vehicle to steer at the limit angle in this direction. When the rear wheel is turned at a limit angle in the left and right directions, it cannot avoid obstacles on the side of the vehicle body, and the rear wheel steering controller stops the control of the rear wheel steering of the vehicle.

When the vehicle is moving forward at a speed of ≤30Km/h: the panoramic surround view system inputs the gap value between the vehicle body side radar and surrounding obstacles to the CAN bus, and the rear wheel steering controller reads the signal from the CAN bus. Thereby, the value of the gap between the outer side and the obstacle when the vehicle body is turned can be obtained.

Beneficial effects of the present invention:

In terms of control strategy, the present invention links the panoramic surround view system with the rear wheel steering system. Under certain low-speed forward steering conditions, the control of the rear wheel steering of the vehicle is stopped, and the movement trajectory of the rear of the vehicle body is kept at the movement trajectory of the front of the vehicle body. In order to avoid the occurrence of collision accidents; under specific low-speed reverse steering driving conditions, the rear wheel turning angle is controlled to a limit angle in a certain direction, which is convenient for reversing into the garage.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the drawings to be used in the description of the embodiments of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the contents of the embodiments of the present invention and these drawings without any creative effort.

FIG. 1 is a schematic diagram of a vehicle when there is an obstacle on the side when the vehicle is running.

FIG. 2 is a schematic diagram of the tire steering of a vehicle without rear wheel steering during forward steering.

FIG. 3 is a schematic diagram of tire steering of a vehicle with rear wheel steering during forward steering.

FIG. 4 is a reverse route calculated when the rear wheel steering controller controls the steering angle of the rear wheels to be 0 degrees in the first embodiment.

FIG. 5 is the reverse route when the rear wheel is turned to the left at a limit angle in the first embodiment and avoids an obstacle on the side of the vehicle body.

FIG. 6 is a reverse route calculated when the rear wheel steering controller controls the steering angle of the rear wheels to be 0 degrees in the second embodiment.

FIG. 7 shows the reverse route when the rear wheels are turned to the right at a limit angle to avoid obstacles on the side of the vehicle body in the second embodiment.

Among them: 1 vehicle front wheel; 2 vehicle rear wheel; 3 vehicle; 4 obstacle.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all structures related to the present invention.

In the description of the present invention, unless otherwise expressly specified and limited, the terms "connected", "connected" and "fixed" should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integrated ; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

In the present invention, unless otherwise expressly specified and limited, a first feature "on" or "under" a second feature may include the first and second features in direct contact, or may include the first and second features Not directly but through additional features between them. Also, the first feature being "above", "over" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is level higher than the second feature. The first feature is "below", "below" and "below" the second feature includes the first feature being directly below and diagonally below the second feature, or simply means that the first feature has a lower level than the second feature.

In the description of this embodiment, the terms "up", "down", "left", "right" and other azimuth or positional relationships are based on the azimuth or positional relationship shown in the accompanying drawings, which are only for the convenience of description and simplifying operations. It is not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. In addition, the terms "first" and "second" are only used for distinction in description, and have no special meaning.

As shown in Fig. 2, for a vehicle without rear wheel steering, when turning forward, the movement trajectory of the rear of the vehicle body on the outer side of the steering is within the movement trajectory of the front of the vehicle body.

As shown in Figure 3, for a vehicle equipped with rear-wheel steering, the steering angle of the rear-wheel is opposite to that of the front-wheel when driving at low speed, and the trajectory of the rear of the vehicle body exceeds the trajectory of the front of the vehicle when it is turned to the outside, and it is easy to collide with obstacles.

Example 1

When the vehicle is moving forward at a speed of ≤30Km/h:

When the gap between the outer side of the vehicle body and the obstacle is ≤0.3m, and the vehicle speed is ≤30Km/h, and the front wheel of the vehicle has a steering angle, the rear wheel steering controller controls the steering angle of the rear wheel to 0 degrees ;When the gap value between the outer side of the vehicle body and the obstacle is greater than or equal to 0.5mm, the rear wheel steering controller returns to the normal control function of the rear wheel steering;

The value of the gap between the outer side of the vehicle body and the obstacle when turning is shown in Figure 1. When the vehicle is driving normally, there is an obstacle on the right side of the vehicle body, so the vehicle body needs to turn left to avoid the obstacle at this time. That is to say, the outer side of the body when turning is the right side of the body, and the distance between the right side of the body and the obstacle is the gap value between the outer side of the body and the obstacle when turning, which is ≤ 0.3 m;

When the vehicle is in reverse gear at low speed:

When the vehicle is in reverse gear, the rear wheel steering controller controls the steering angle of the rear wheels to be 0 degrees. The panoramic surround view system collects the rotation angle signals of the rear wheels at this time, as shown in Figure 4, and combines the rotation angle signals of the front wheels to calculate the reversing The route is determined according to the position of the obstacles on the side of the vehicle body on the calculated reversing route, and then according to the driving route when the rear wheel of the vehicle is turned at a limit angle in the left and right directions. As shown in Figure 5, the rear wheel is in the left direction. When the direction is turned at a limit angle, it can avoid obstacles on the side of the vehicle body, and the rear wheel steering controller controls the rear wheel of the vehicle to turn at a limit angle in this direction.

Example 2

When the vehicle is traveling at a speed of ≤30Km/h:

When the gap between the outer side of the vehicle body and the obstacle is less than or equal to 0.3m, and the vehicle speed is less than or equal to 30Km/h, and the front wheel of the vehicle has a turning angle, the rear wheel steering controller controls the steering angle of the rear wheel to 0 degrees; When the gap between the outer side of the vehicle body and the obstacle is greater than or equal to 0.5mm, the rear wheel steering controller resumes the normal control function of the rear wheel steering;

When driving in reverse at low speed:

As shown in Figure 2, when the vehicle is in reverse gear, the rear wheel steering controller controls the steering angle of the rear wheels to be 0 degrees. Calculate the reversing route according to the corner signal of the vehicle, according to the position of the obstacles on the side of the vehicle body on the calculated reversing route, and then according to the driving route of the vehicle rear wheel steering at a limit angle in the left and right directions, as shown in Figure 7, the rear wheel is in the left and right directions. When steering in the right direction at a limit angle, it can avoid obstacles on the side of the vehicle body, and the rear wheel steering controller controls the rear wheel of the vehicle to steer at a limit angle in this direction.

When driving at low speed:

The panoramic surround view system outputs the gap value between the body side radar and the surrounding obstacles to the CAN bus, and the rear wheel steering controller reads the signal from the CAN bus. When the vehicle speed is less than or equal to 30Km/h, when the front wheel of the vehicle has a turning angle, the rear wheel turning angle is set to zero. When the vehicle body turns to the outer side and the obstacle clearance value is ≥ 0.5mm, the rear wheel steering returns to the normal and usable state.

When driving in reverse at low speed:

The rear wheel steering angle returns to 0 degrees when the reverse gear is engaged. The panoramic surround view system collects the rear wheel angle signal, and calculates the reversing route according to the front and rear wheel angle signals. The driving route when the direction is at the limit angle. If the limit angle in a certain direction can avoid obstacles, the steering is based on this limit angle. If the obstacle cannot be avoided in both directions, the 0-degree turning angle is maintained.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the protection scope of the present invention is not limited to the specific details in the above-mentioned embodiments. Within the technical scope disclosed by the present invention, equivalent replacements or changes are made according to the technical solutions and the inventive concept of the present invention, and these simple modifications all belong to the protection scope of the present invention.

In addition, it should be noted that the specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner unless they are inconsistent. In order to avoid unnecessary repetition, the present invention provides The combination method will not be specified otherwise.

In addition, the various embodiments of the present invention can also be combined arbitrarily, as long as it does not violate the spirit of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

A method for controlling rear wheel steering when a vehicle is running at low speed, which is characterized by comprising the following contents:

When the vehicle is traveling at a speed of ≤30Km/h:

When the gap value between the outer side of the vehicle body and the obstacle is less than or equal to 0.3m, and the front wheel of the vehicle has a turning angle, the rear wheel steering controller controls the steering angle of the rear wheel to 0 degrees; When the gap value between the obstacle and the obstacle is greater than or equal to 0.5mm, the rear wheel steering controller resumes the control function of the rear wheel steering;

When driving in reverse at low speed:

When the vehicle is in reverse gear, the rear wheel steering controller controls the steering angle of the rear wheels to 0 degrees. The panoramic surround view system collects the rotation angle signals of the rear wheels at this time, and calculates the reversing route based on the rotation angle signals of the front wheels. The position of the obstacle on the side of the vehicle body on the reversing route, if the rear wheel can avoid the obstacle on the side of the vehicle body when turning at a limit angle in a certain direction, the rear wheel steering controller will control the rear wheel of the vehicle to steer at the limit angle in this direction. When the rear wheel is turned at a limit angle in the left and right directions, it cannot avoid obstacles on the side of the vehicle body, and the rear wheel steering controller stops the control of the rear wheel steering of the vehicle.
The method for controlling rear wheel steering when the vehicle is running at low speed according to claim 1, wherein when the vehicle is moving forward at a speed of ≤ 30Km/h: the panoramic surround view system compares the data detected by the radar on the side of the vehicle with the surrounding area. The gap value of the obstacle is input to the CAN bus, and the rear wheel steering controller reads the signal from the CAN bus, so as to obtain the gap value between the outer side and the obstacle when the body turns.