Method and device for determining angle value of rear wheel, storage medium and electronic device

Abstract

The invention discloses a method and device for determining a rear wheel turning angle value, a storage medium and an electronic device, and the method comprises the steps: determining a feed-forward rear wheel turning angle value of a target vehicle according to a front wheel turning angle value of the target vehicle under the condition that the target vehicle triggers a crabbing mode; acquiring a target yaw angle of the target vehicle, and determining a feedback rear wheel steering angle value of the target vehicle according to the target yaw angle; the target rear wheel turning angle value of the target vehicle is determined according to the feedforward rear wheel turning angle value and the feedback rear wheel turning angle value, by adopting the embodiment, the problem that the moving effect of a crabbing mode is poor due to the fact that most of theoretical methods of the rear wheel turning crabbing mode in the related technology adopt a feedforward-only control method is solved.

Description

Technical Field

[0001] This application relates to the field of motion control, and more specifically, to a method and apparatus for determining the rear wheel steering angle, a storage medium, and an electronic device. Background Technology

[0002] With the popularization and deepening of intelligent driving technology, controller domain control and actuator drive-by-wire have become two major development trends in intelligent chassis. Rear-wheel steering is often the first subsystem to achieve functional relocation, so rear-wheel steering assist can be designed to allow the rear wheel angle to adjust with changes in vehicle speed and steering wheel angle. Crawl mode is defined as a special steering mode in which the rear wheel angle follows the front wheel angle in the same direction and with the same magnitude, thereby improving the vehicle's convenience in tight spaces or when making U-turns.

[0003] The main characteristics of rear-wheel steering are large-angle counter-steering at low speeds and small-angle steering in the same direction at high speeds. Large-angle counter-steering at low speeds helps reduce the turning radius, improving vehicle agility and cornering ability; small-angle steering in the same direction at high speeds accelerates lateral acceleration response, improving vehicle stability during high-speed lane changes. Crab steering is a special type of same-direction steering, but most theoretical methods for rear-wheel steering crab steering modes in related technologies use only feedforward control methods, resulting in poor movement performance.

[0004] Regarding the relevant technologies, most theoretical methods for the rear wheel cornering crab mode adopt only feedforward control methods, which leads to poor movement performance of the crab mode, and no effective solution has been proposed yet.

[0005] Therefore, it is necessary to improve the relevant technology to overcome the aforementioned defects. Summary of the Invention

[0006] This application provides a method and apparatus for determining the rear wheel steering angle, a storage medium, and an electronic device, to at least solve the problem that most theoretical methods for the rear wheel steering angle crab mode adopt only a feedforward control method, resulting in poor movement performance of the crab mode.

[0007] According to one aspect of the embodiments of this application, a method for determining the rear wheel steering angle value is provided, comprising: when a target vehicle triggers a crab mode, determining the feedforward rear wheel steering angle value of the target vehicle based on the front wheel steering angle value of the target vehicle; obtaining the target yaw angle of the target vehicle, and determining the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle; and determining the target rear wheel steering angle value of the target vehicle based on the feedforward rear wheel steering angle value and the feedback rear wheel steering angle value.

[0008] Further, determining the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value includes: determining the gain value of the yaw rate of the target vehicle; and determining the feedforward rear wheel angle value based on the gain value of the yaw rate and the front wheel angle value.

[0009] Further, determining the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle includes: determining the desired yaw angle of the target vehicle, and determining the deviation value between the desired yaw angle and the target yaw angle; calculating the deviation value according to the feedback control algorithm to obtain the feedback rear wheel steering angle value.

[0010] Further, determining the target rear wheel angle value of the target vehicle based on the feedforward rear wheel angle value and the feedback rear wheel angle value includes: summing the feedforward rear wheel angle value and the feedback rear wheel angle value to obtain a base rear wheel angle value; determining the target minimum rear wheel angle value corresponding to the target vehicle speed based on the wheel angle dead zone curve of the target vehicle, wherein the horizontal axis of the wheel angle dead zone curve is used to indicate the vehicle speed of the target vehicle, and the vertical axis is used to indicate the minimum rear wheel angle value; and determining the target rear wheel angle value based on the target minimum rear wheel angle value and the base rear wheel angle value.

[0011] Further, determining the target rear wheel angle value based on the target minimum rear wheel angle value and the base rear wheel angle value includes: determining a first size relationship between the target minimum rear wheel angle value and the base rear wheel angle value; determining the target rear wheel angle value as a target value when the first size relationship indicates that the base rear wheel angle value is less than the target minimum rear wheel angle value; and determining the base rear wheel angle value as the target rear wheel angle value when the first size relationship indicates that the base rear wheel angle value is greater than or equal to the target minimum rear wheel angle value.

[0012] Further, determining the target rear wheel angle value of the target vehicle based on the feedforward rear wheel angle value and the feedback rear wheel angle value includes: determining a second relationship between the target limit value of the rear wheel angle of the target vehicle and the base rear wheel angle value; determining the base rear wheel angle value as the target rear wheel angle value when the second relationship indicates that the base rear wheel angle value is less than or equal to the target limit value; and determining the target limit value as the target rear wheel angle value when the second relationship indicates that the base rear wheel angle value is greater than the target limit value.

[0013] Further, before determining the second magnitude relationship between the target limit value of the rear wheel steering angle of the target vehicle and the base rear wheel steering angle value, the method further includes: determining a first limit value of the rear wheel steering angle, and determining a second limit value of the rear wheel steering angle corresponding to the target vehicle speed based on the limit value curve of the target vehicle, wherein the horizontal axis of the limit value curve is used to indicate the vehicle speed of the target vehicle, and the vertical axis is used to indicate the limit value; if the first limit value is less than or equal to the second limit value, the first limit value is determined to be the target limit value; if the first limit value is greater than the second limit value, the second limit value is determined to be the target limit value.

[0014] Further, obtaining the target yaw angle of the target vehicle includes: determining a first yaw angle of the target vehicle based on the yaw rate of the target vehicle, and determining a second yaw angle of the target vehicle based on the lane line information of the target vehicle; and performing a weighted summation of the first yaw angle and the second yaw angle to determine the target yaw angle.

[0015] Further, determining the second yaw angle of the target vehicle based on the lane line information of the target vehicle includes: determining the lateral displacement change rate of the target vehicle based on the lane line information; calculating the lateral displacement change rate based on a target formula to obtain the second yaw angle, wherein the target formula includes: Yaw2 = tan -1 C1 and Yaw2 are the second yaw angles, and C1 is the rate of change of the lateral displacement.

[0016] Further, before determining the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value of the target vehicle, the process includes: obtaining the steering wheel angle value of the target vehicle and the transmission ratio of the steering system of the target vehicle; and determining the front wheel angle value based on the steering wheel angle value and the transmission ratio.

[0017] Furthermore, before determining the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value of the target vehicle, the method further includes: triggering the crab mode under preset conditions, wherein the preset conditions include: receiving a trigger command from the target object, determining that the front wheel angle value of the target vehicle is less than the target amplitude limit value of the target vehicle, the front wheel steering and rear wheel steering of the target vehicle are fault-free, the target function of the target vehicle is not activated, and the target speed of the target vehicle is less than the preset speed.

[0018] According to another aspect of the embodiments of this application, a device for determining the rear wheel steering angle value is also provided, comprising: a first determining module, configured to determine the feedforward rear wheel steering angle value of the target vehicle based on the front wheel steering angle value of the target vehicle when the target vehicle triggers a crab mode; a second determining module, configured to acquire the target yaw angle of the target vehicle and determine the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle; and a third determining module, configured to determine the target rear wheel steering angle value of the target vehicle based on the feedforward rear wheel steering angle value and the feedback rear wheel steering angle value.

[0019] According to another aspect of the embodiments of this application, a computer-readable storage medium is also provided, wherein a computer program is stored in the computer program, and the computer program is configured to execute the above-described method for determining the rear wheel steering angle value when running.

[0020] According to another aspect of the embodiments of this application, an electronic device is also provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the method for determining the rear wheel steering angle value through the computer program.

[0021] According to yet another embodiment of this application, a computer program product is also provided, including a computer program that, when executed by a processor, implements the steps in any of the above method embodiments.

[0022] This application, when a target vehicle triggers crab mode, determines the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value; obtains the target yaw angle of the target vehicle, and determines the feedback rear wheel angle value of the target vehicle based on the target yaw angle; and determines the target rear wheel angle value of the target vehicle based on the feedforward and feedback rear wheel angle values. In other words, this embodiment determines the rear wheel angle value of the vehicle in crab mode using a feedforward and feedback method. By adopting the above technical solution, it solves the problem that most theoretical methods for crab mode rear wheel angle control in related technologies use only feedforward control methods, resulting in poor movement performance in crab mode, thereby improving the movement performance of crab mode. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and, together with the description thereof, serve to explain this application and do not constitute an undue limitation thereof. In the drawings:

[0024] Figure 1 This is a hardware structure block diagram of a computer device for a method of determining the rear wheel steering angle value according to an embodiment of this application;

[0025] Figure 2This is a flowchart of a method for determining the rear wheel steering angle value according to an embodiment of this application;

[0026] Figure 3 This is a diagram of a steering device according to an embodiment of this application (I);

[0027] Figure 4 This is a diagram (II) of the steering device according to an embodiment of this application;

[0028] Figure 5 This is a control block diagram of the rear wheel steering crab mode according to an embodiment of this application;

[0029] Figure 6 This is a flowchart of a method for determining the rear wheel steering angle value according to an optional embodiment of this application;

[0030] Figure 7 This is a structural block diagram of a device for determining the rear wheel steering angle value according to an embodiment of this application. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0032] It should be noted that the terms and terms such as "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] The methods and embodiments provided in this application can be executed in a computer device or a similar computing device. Taking running on a computer device as an example, Figure 1 This is a hardware block diagram of a computer device for a method of determining the rear wheel steering angle value according to an embodiment of this application. Figure 1 As shown, a computer device may include one or more ( Figure 1Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor (MPU) or a programmable logic device (PLD)) and a memory 104 for storing data are also shown. In one exemplary embodiment, the computer device may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that… Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the computer device described above. For example, the computer device may also include components that are more... Figure 1 The more or fewer components shown, or having the same Figure 1 Equivalent functions or ratios shown Figure 1 The functions shown have more different configurations.

[0034] In this embodiment of the application, the computer device described above can be an on-board computer in a vehicle.

[0035] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the method for determining the rear wheel steering angle value in this embodiment. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, which is equivalent to implementing the above-described method. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0036] The transmission device 106 is used to receive or send data via a network. In one example, the transmission device 106 includes a network interface module, through which communication with other modules of the vehicle can be achieved.

[0037] The transmission device 106 of the vehicle computer typically communicates with other devices via vehicle bus systems such as CAN bus or LIN bus. These bus systems enable high-speed and reliable data transmission, and also support communication and collaboration between multiple devices.

[0038] In vehicle systems, the transmission and interaction between various devices is typically achieved through the vehicle bus system. For example, when the driver presses the brake pedal, the sensors in the braking system send signals to the vehicle controller, which then transmits instructions to the braking system via the bus system, thereby enabling the vehicle to brake.

[0039] This embodiment provides a method for determining the rear wheel steering angle value. Figure 2 This is a flowchart of a method for determining the rear wheel steering angle value according to an embodiment of this application. The process includes the following steps:

[0040] Step S202: When the target vehicle triggers the crab mode, determine the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value of the target vehicle;

[0041] Step S204: Obtain the target yaw angle of the target vehicle, and determine the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle;

[0042] Step S206: Determine the target rear wheel steering angle value of the target vehicle based on the feedforward rear wheel steering angle value and the feedback rear wheel steering angle value.

[0043] Through the above steps, when the target vehicle triggers the crab mode, the feedforward rear wheel angle value of the target vehicle is determined based on the front wheel angle value; the target yaw angle of the target vehicle is obtained, and the feedback rear wheel angle value of the target vehicle is determined based on the target yaw angle; the target rear wheel angle value of the target vehicle is determined based on the feedforward rear wheel angle value and the feedback rear wheel angle value. That is, in this embodiment, the rear wheel angle value of the vehicle in crab mode is determined by a feedforward and feedback method. By adopting the above technical solution, the problem that most theoretical methods for rear wheel angle crab mode in related technologies use only a feedforward control method, resulting in poor movement performance in crab mode, is solved, thereby improving the movement performance of crab mode.

[0044] Optionally, step S202 above can be implemented in the following way:

[0045] Determine the gain value of the yaw rate of the target vehicle; determine the feedforward rear wheel steering angle value based on the gain value of the yaw rate and the front wheel steering angle value.

[0046] In this embodiment of the application, the gain value γ of the yaw rate derived from four-wheel steering is... tar This can be expressed by the following formula: Where, δ f δ is the front wheel steering angle value. rdenoted as feedforward rear wheel steering angle, u as vehicle speed, m as vehicle mass, a as distance from center of gravity to front axle, b as distance from center of gravity to rear axle, l as wheelbase, k1 as front wheel composite lateral stiffness (N / Rad), and k2 as front wheel composite lateral stiffness (N / Rad).

[0047] In this embodiment of the application, in order to improve the movement effect of the crab-like movement mode, the crab-like movement mode requires the gain value of the yaw rate to be as small as possible. For example, the gain value can be set to 0. In this case, δ r =δ f That is, the front wheel steering angle value is set to the feedforward rear wheel steering angle value.

[0048] Optionally, step S204 above can also be implemented in the following way: determining the desired yaw angle of the target vehicle, and determining the deviation value between the desired yaw angle and the target yaw angle; calculating the deviation value according to the feedback control algorithm to obtain the feedback rear wheel steering angle value.

[0049] It should be noted that the above feedback control algorithm can be understood as a proportional-integral-derivative (PID) algorithm. The PID algorithm adjusts the input by measuring the error between the output and the desired value so that the system output is as close as possible to the desired value. Therefore, in this embodiment, the deviation between the desired yaw angle and the target yaw angle is obtained, and the feedback rear wheel rotation angle is determined based on the deviation between the desired yaw angle and the target yaw angle.

[0050] Optionally, step S206 above can also be implemented in the following way: summing the feedforward rear wheel angle value and the feedback rear wheel angle value to obtain the base rear wheel angle value; determining the target minimum rear wheel angle value corresponding to the target vehicle speed based on the wheel angle dead zone curve of the target vehicle, wherein the horizontal axis of the wheel angle dead zone curve is used to indicate the vehicle speed of the target vehicle, and the vertical axis is used to indicate the minimum rear wheel angle value; determining the target rear wheel angle value based on the target minimum rear wheel angle value and the base rear wheel angle value.

[0051] The determination of the target rear wheel angle value based on the target minimum rear wheel angle value and the base rear wheel angle value includes: determining a first size relationship between the target minimum rear wheel angle value and the base rear wheel angle value; determining the target rear wheel angle value as a target value when the first size relationship indicates that the base rear wheel angle value is less than the target minimum rear wheel angle value; and determining the base rear wheel angle value as the target rear wheel angle value when the first size relationship indicates that the base rear wheel angle value is greater than or equal to the target minimum rear wheel angle value.

[0052] Having obtained both the feedforward and feedback rear wheel steering angle values, summing these values ​​yields the base rear wheel steering angle value for the target vehicle. Beyond this base value, dead zone protection is also considered, ensuring that the crab mode is not activated when the vehicle is traveling straight. Therefore, dead zone protection based on lane departure limits is necessary. Lane departure limits are typically defined within 0.25m. According to this target deviation, the rear wheel steering angle dead zone limit varies at different vehicle speeds. Wheel steering angle injection tests can be performed on a real vehicle to obtain a wheel steering angle dead zone curve that varies with vehicle speed. The horizontal axis of the wheel steering angle dead zone curve indicates the target vehicle's speed, and the vertical axis indicates the minimum rear wheel steering angle value.

[0053] If the base rear wheel angle value is less than the target minimum rear wheel angle value, the target rear wheel angle value is determined to be the target value (e.g., 0), thus triggering dead zone protection; if the base rear wheel angle value is greater than or equal to the target minimum rear wheel angle value, the base rear wheel angle value is determined to be the target rear wheel angle value, thus triggering the crab mode normally.

[0054] In this embodiment of the application, the rear wheel steering angle in the final crab mode is output through dead zone processing, which can improve the safety of vehicle operation.

[0055] Optionally, step S206 above can also be implemented in the following way: determining a second size relationship between the target limit value of the rear wheel steering angle of the target vehicle and the base rear wheel steering angle value; when the second size relationship indicates that the base rear wheel steering angle value is less than or equal to the target limit value, determining the base rear wheel steering angle value as the target rear wheel steering angle value; when the second size relationship indicates that the base rear wheel steering angle value is greater than the target limit value, determining the target limit value as the target rear wheel steering angle value.

[0056] In other words, in this embodiment of the application, the basic rear wheel steering angle value is also subject to a limit. That is, the output of the rear wheel steering angle value in the crab mode must meet the system capability and functional safety boundary. Therefore, it is necessary to set a maximum rear wheel steering angle value (i.e., target limit value) for the target vehicle. If the basic rear wheel steering angle value is less than or equal to the target limit value, the basic rear wheel steering angle value is determined to be the target rear wheel steering angle value. If the basic rear wheel steering angle value is greater than the target limit value, the target limit value is determined to be the target rear wheel steering angle value.

[0057] Optionally, embodiments of this application provide a method for determining a target amplitude limit value for a vehicle, specifically as follows: determining a first amplitude limit value for the rear wheel steering angle, and determining a second amplitude limit value for the rear wheel steering angle corresponding to the target vehicle speed based on the amplitude limit value curve of the target vehicle, wherein the horizontal axis of the amplitude limit value curve is used to indicate the vehicle speed of the target vehicle, and the vertical axis is used to indicate the amplitude limit value; if the first amplitude limit value is less than or equal to the second amplitude limit value, the first amplitude limit value is determined to be the target amplitude limit value; if the first amplitude limit value is greater than the second amplitude limit value, the second amplitude limit value is determined to be the target amplitude limit value.

[0058] The target speed mentioned above can be understood as the current speed of the target vehicle.

[0059] It should be noted that the steering load of the rear-wheel steering system varies at different steering angles, with a higher load at lower vehicle speeds. Based on the output rack force characteristics of the rear-wheel steering gear and the hard point design of the vehicle's mechanical system, a maximum limit value 1 (i.e., the first limit value mentioned above) is preset for the steering system. The rear-wheel steering system is matched with the target vehicle model for real-vehicle rear-wheel steering function safety fault injection testing. Under the premise that the vehicle does not deviate from the current lane and does not become unstable when the rear-wheel steering fails at different vehicle speeds, the executable maximum limit value 2 (i.e., the second limit value mentioned above) that varies with vehicle speed can be obtained. By determining the minimum value of the maximum limit value 1 and the maximum limit value 2, the maximum limit value 3 (i.e., the target limit value mentioned above) that meets the system capability and functional safety boundary is obtained.

[0060] Optionally, this application embodiment also provides a method for obtaining the target yaw angle of the target vehicle, specifically as follows: determining the first yaw angle of the target vehicle based on the yaw rate of the target vehicle, and determining the second yaw angle of the target vehicle based on the lane line information of the target vehicle; performing a weighted summation of the first yaw angle and the second yaw angle to determine the target yaw angle.

[0061] Determining the second yaw angle of the target vehicle based on its lane information includes: determining the lateral displacement rate of change of the target vehicle based on the lane information; and calculating the lateral displacement rate of change based on a target formula to obtain the second yaw angle, wherein the target formula includes: Yaw2 = tan -1 C1 and Yaw2 are the second yaw angles, and C1 is the rate of change of the lateral displacement.

[0062] First, the first yaw angle, Yaw1, is obtained by integrating the yaw rate signal acquired by the Inertial Measurement Unit (IMU). The camera sensing system then outputs lane line information, where the lane line curve formula is: Lateral Offset = C0 + C1*R + C2*R 2 +C3*R 3 C0 is the current lateral displacement, C1 is the rate of change of lateral displacement, C2 is the curvature coefficient, and C3 is the curvature coefficient. That is, the rate of change of lateral displacement is determined according to the above lane line curve formula.

[0063] According to the formula: Yaw2 = tan -1 C1 is used to obtain the second yaw angle Yaw2. After fusion by weighted averaging, the target yaw angle Yaw of the vehicle is obtained.

[0064] Optionally, this application embodiment also provides a method for determining the front wheel steering angle value of a vehicle, specifically as follows: obtaining the steering wheel angle value of the target vehicle and the transmission ratio of the steering system of the target vehicle; determining the front wheel steering angle value based on the steering wheel angle value and the transmission ratio.

[0065] That is, to acquire the steering wheel angle collected by the sensor and convert the steering wheel angle into the front wheel angle.

[0066] Optionally, this application embodiment also provides a method for triggering the crab mode, as follows: the crab mode is triggered when preset conditions are met, wherein the preset conditions include: receiving a trigger command from the target object, determining that the front wheel steering angle of the target vehicle is less than the target amplitude limit of the target vehicle, the front wheel steering and rear wheel steering of the target vehicle are fault-free, the target function of the target vehicle is not activated, and the target speed of the target vehicle is less than the preset speed.

[0067] The aforementioned receiving of the trigger command from the target object can be understood as the driver pressing a trigger switch. This switch can be a physical switch, a virtual switch, or a command sent by the target object through an app.

[0068] The aforementioned target functions may be: Anti-lock Braking System (ABS); Electronic Stability Program (ESP); Advanced Driver Assistance Systems (ADAS).

[0069] Obviously, the embodiments described above are only some embodiments of this application, and not all embodiments. To better understand the method for determining the rear wheel steering angle value, the following description, in conjunction with embodiments, illustrates the process, but is not intended to limit the technical solutions of the embodiments of this application. Specifically:

[0070] To better understand the embodiments of this application, we will first introduce the vehicle's steering mechanism, such as... Figure 3 and Figure 4 As shown, the steering device includes: steering wheel 1, steering column 2, rack and pinion reduction mechanism 3, front steering controller 4, rack mechanism 5, rear steering controller 6, belt drive reduction mechanism 7, front wheel 8, and rear wheel 9.

[0071] In an optional embodiment, Figure 5 This is a control block diagram of the rear wheel steering crab mode according to an embodiment of this application, such as... Figure 5 As shown, it includes: a front wheel steering angle and vehicle speed calculation module, used to calculate the front wheel steering angle δ f and vehicle speed v x The input is sent to the control module, which includes a feedforward control module and a feedback control module.

[0072] The yaw rate fusion module is used to obtain the yaw rate signal ω from the IMU. r The integral yields the first yaw angle, Yaw1; the camera perception system outputs lane line information, and according to the following formula, Yaw2 = tan -1 C1 is used to obtain the second yaw angle Yaw2, where C1 is the lateral displacement rate coefficient. Then, the actual yaw angle Yaw of the vehicle is obtained by fusion through weighted averaging.

[0073] The control module is used to determine the front wheel steering angle δ. f Vehicle speed v x The rear wheel steering angle δ is obtained by superimposing the actual yaw angle (equivalent to the target yaw angle in the above embodiment) with the feedforward feedback. r_F (Equivalent to the base rear wheel steering angle value in the above embodiment);

[0074] Dead zone protection module, used for δ r_F Processing is performed to obtain the rear wheel steering angle δ after dead zone protection. r_dz ;

[0075] Limiting module, used for δ r_dz Processing is performed to obtain the rear wheel steering angle δ after amplitude limiting. r_lim ;

[0076] The status management module is used to determine whether the vehicle has triggered the crab mode;

[0077] The Crab Movement Function Entry and Exit Condition Judgment Module is used to determine whether to trigger the Crab Movement mode of the vehicle and whether to exit the Crab Movement mode of the vehicle based on the associated conditions of the Crab Movement mode.

[0078] In an optional embodiment, Figure 6 This is a flowchart of a method for determining the rear wheel steering angle value according to an optional embodiment of this application. The specific steps are as follows:

[0079] Step S601: Convert the steering wheel angle HWA collected by the sensor into the front wheel angle δ f ;

[0080] Step S602: Calculate the feedforward rear wheel steering angle value in crab mode. The steady-state yaw rate gain formula derived from four-wheel steering is as follows:

[0081] Where, δ f δ is the front wheel steering angle value. r Here, δ represents the feedforward rear wheel steering angle, u is the vehicle speed, m is the vehicle mass, a is the distance from the center of gravity to the front axle, b is the distance from the center of gravity to the rear axle, l is the wheelbase, k1 is the front wheel composite lateral stiffness (N / Rad), k2 is the front wheel composite lateral stiffness (N / Rad), and crabbing requires a yaw rate gain of 0; therefore, δ r =δ f .

[0082] Step S603: Integrate the yaw rate signal acquired by the IMU to obtain the first yaw angle Yaw1; the camera perception system outputs lane line information, and according to the following formula, Yaw2 = tan -1 C1 is used to obtain the second yaw angle Yaw2, where C1 is the lateral displacement rate coefficient; the actual yaw angle Yaw of the controlled vehicle is obtained after fusion by weighted averaging.

[0083] The formula for the lane line curve is: Lateral Offset = C0 + C1*R + C2*R 2 +C3*R 3 C0 is the current lateral displacement, C1 is the rate of change of lateral displacement, C2 is the curvature coefficient, and C3 is the curvature coefficient. The rate of change of lateral displacement is determined according to the above lane curve formula.

[0084] Step S604: The target yaw angle for the crab mode is 0. Calculate the yaw angle deviation between the target yaw angle and the actual yaw angle Yaw obtained in step S603. Output the feedback rear wheel steering angle value through PID control. The feedback rear wheel steering angle value is superimposed with the feedforward rear wheel steering angle to obtain the basic rear wheel steering angle for the crab mode.

[0085] Step S605: Determine the relationship between the base rear wheel angle and the target minimum rear wheel angle. If the base rear wheel angle is greater than or equal to the target minimum rear wheel angle, output the base rear wheel angle; otherwise, output 0.

[0086] In the crab mode, the dead zone must ensure that the function is not activated when the vehicle is traveling straight. Therefore, corner dead zone protection is required based on the lane departure limit. The lane departure limit is generally defined within 0.25m. According to this deviation target, the rear wheel corner dead zone limit is different at different vehicle speeds. Wheel corner injection tests can be performed on a real vehicle to obtain the wheel corner dead zone curve that varies with vehicle speed. The horizontal axis of the wheel corner dead zone curve represents the vehicle speed, and the vertical axis represents the minimum rear wheel corner angle.

[0087] Step S606: Determine the relationship between the base rear wheel angle and the target limit value. When the base rear wheel angle is greater than or equal to the target limit value, output the target limit value. When the base rear wheel angle is less than the target limit value, output the base rear wheel angle.

[0088] It should be noted that the steering angle output in crab mode must meet the system's capabilities and functional safety boundaries; the steering load of the rear-wheel steering system varies at different steering angles, with higher loads at lower vehicle speeds; based on the output rack force characteristics of the rear-wheel steering gear and the hard point design of the vehicle's mechanical system, the steering system has a maximum angle limit 1; the rear-wheel steering system is matched with the target vehicle model for real-vehicle rear-wheel steering functional safety fault injection testing, assuming that the vehicle does not deviate from its current lane and does not become unstable when the rear-wheel steering fails at different vehicle speeds, the maximum executable steering angle limit 2 that varies with vehicle speed can be obtained; taking the minimum value of the above maximum angle limit 1 and maximum angle limit 2, the maximum angle limit 3 that meets the system's capabilities and functional safety boundaries is obtained.

[0089] It should be further noted that the following five conditions are required to trigger the crab-walking mode:

[0090] 1) The driver presses the trigger switch;

[0091] 2) The front wheel steering angle is less than the maximum angle limit of 3 mentioned above;

[0092] 3) The vehicle's front and rear wheel steering functions without faults;

[0093] 4) The vehicle's ABS, ESP, and ADAS functions are not activated;

[0094] 5) The vehicle speed is less than the preset speed.

[0095] When the above conditions are met simultaneously, the crab-walking function is activated; during vehicle operation, the above steps are repeated according to a fixed sampling period, and the target rear wheel steering angle is output.

[0096] The following technical effects can be achieved through the above embodiments:

[0097] 1) The method for determining the rear wheel steering angle value in this application will not affect the calculation process and accuracy of the rear wheel steering follow-up function due to changes in vehicle conditions such as vehicle load. Therefore, the method for determining the rear wheel steering angle value in this application is robust to external disturbances.

[0098] 2) The method for determining the rear wheel steering angle value in this application does not require additional sensors for rear wheel steering or feedback of vehicle state quantities, and can meet the constraint-based multi-objective requirements that take into account driving experience, system selection, actuator capability and safety.

[0099] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods of the various embodiments of this application.

[0100] This embodiment also provides a device for determining the rear wheel steering angle value. This device is used to implement the above embodiments and preferred embodiments, and will not be repeated as already described. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0101] Figure 7 This is a structural block diagram of a device for determining the rear wheel steering angle value according to an embodiment of this application. The device includes:

[0102] The first determining module 72 is used to determine the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value of the target vehicle when the target vehicle triggers the crab mode;

[0103] The second determining module 74 is used to obtain the target yaw angle of the target vehicle and determine the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle.

[0104] The third determining module 76 is used to determine the target rear wheel angle value of the target vehicle based on the feedforward rear wheel angle value and the feedback rear wheel angle value.

[0105] This application, when a target vehicle triggers crab mode, determines the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value; obtains the target yaw angle of the target vehicle, and determines the feedback rear wheel angle value of the target vehicle based on the target yaw angle; and determines the target rear wheel angle value of the target vehicle based on the feedforward and feedback rear wheel angle values. In other words, this embodiment determines the rear wheel angle value of the vehicle in crab mode using a feedforward and feedback method. By adopting the above technical solution, it solves the problem that most theoretical methods for crab mode rear wheel angle control in related technologies use only feedforward control methods, resulting in poor movement performance in crab mode, thereby improving the movement performance of crab mode.

[0106] Furthermore, the first determining module 72 is used to determine the gain value of the yaw rate of the target vehicle; and to determine the feedforward rear wheel steering angle value based on the gain value of the yaw rate and the front wheel steering angle value.

[0107] Furthermore, the second determining module 74 is used to determine the desired yaw angle of the target vehicle and the deviation value between the desired yaw angle and the target yaw angle; and to calculate the deviation value according to the feedback control algorithm to obtain the feedback rear wheel steering angle value.

[0108] Further, the third determining module 76 is used to sum the feedforward rear wheel angle value and the feedback rear wheel angle value to obtain the base rear wheel angle value; determine the target minimum rear wheel angle value corresponding to the target vehicle speed based on the wheel angle dead zone curve of the target vehicle, wherein the horizontal axis of the wheel angle dead zone curve is used to indicate the vehicle speed of the target vehicle, and the vertical axis is used to indicate the minimum rear wheel angle value; and determine the target rear wheel angle value based on the target minimum rear wheel angle value and the base rear wheel angle value.

[0109] Furthermore, the third determining module 76 is used to determine a first size relationship between the target minimum rear wheel steering angle value and the base rear wheel steering angle value; when the first size relationship indicates that the base rear wheel steering angle value is less than the target minimum rear wheel steering angle value, the target rear wheel steering angle value is determined to be a target value; when the first size relationship indicates that the base rear wheel steering angle value is greater than or equal to the target minimum rear wheel steering angle value, the base rear wheel steering angle value is determined to be the target rear wheel steering angle value.

[0110] Furthermore, the third determining module 76 is used to determine a second relationship between the target limit value of the rear wheel steering angle of the target vehicle and the base rear wheel steering angle value; when the second relationship indicates that the base rear wheel steering angle value is less than or equal to the target limit value, the base rear wheel steering angle value is determined to be the target rear wheel steering angle value; when the second relationship indicates that the base rear wheel steering angle value is greater than the target limit value, the target limit value is determined to be the target rear wheel steering angle value.

[0111] Furthermore, the third determining module 76 is used to determine a first limiting value of the rear wheel steering angle, and to determine a second limiting value of the rear wheel steering angle corresponding to the target vehicle speed based on the limiting value curve of the target vehicle, wherein the horizontal axis of the limiting value curve is used to indicate the vehicle speed of the target vehicle, and the vertical axis is used to indicate the limiting value; if the first limiting value is less than or equal to the second limiting value, the first limiting value is determined to be the target limiting value; if the first limiting value is greater than the second limiting value, the second limiting value is determined to be the target limiting value.

[0112] Furthermore, the second determining module 74 is used to determine the first yaw angle of the target vehicle based on the yaw rate of the target vehicle, and to determine the second yaw angle of the target vehicle based on the lane line information of the target vehicle; and to perform a weighted summation of the first yaw angle and the second yaw angle to determine the target yaw angle.

[0113] Further, the second determining module 74 is used to determine the lateral displacement change rate of the target vehicle based on the lane line information; and to calculate the lateral displacement change rate based on the target formula to obtain the second yaw angle, wherein the target formula includes: Yaw2 = tan -1 C1 and Yaw2 are the second yaw angles, and C1 is the rate of change of the lateral displacement.

[0114] Furthermore, the first determining module 72 is used to obtain the steering wheel angle value of the target vehicle and the transmission ratio of the steering system of the target vehicle; and to determine the front wheel angle value based on the steering wheel angle value and the transmission ratio.

[0115] Furthermore, the above-mentioned device also includes: a trigger module, used to trigger the crab mode when preset conditions are met, wherein the preset conditions include: receiving a trigger command from a target object, determining that the front wheel steering angle of the target vehicle is less than the target limit value of the target vehicle, the front wheel steering and rear wheel steering of the target vehicle are fault-free, the target function of the target vehicle is not activated, and the target speed of the target vehicle is less than a preset speed.

[0116] According to another aspect of the embodiments of this application, a computer-readable storage medium is also provided, wherein a computer program is stored in the computer program, and the computer program is configured to execute the above-described method for determining the rear wheel steering angle value when running.

[0117] Optionally, in this embodiment, the storage medium may be configured to store a computer program for performing the following steps:

[0118] S1, when the target vehicle triggers the crab mode, determine the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value of the target vehicle;

[0119] S2, obtain the target yaw angle of the target vehicle, and determine the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle;

[0120] S3, determine the target rear wheel angle value of the target vehicle based on the feedforward rear wheel angle value and the feedback rear wheel angle value.

[0121] In one exemplary embodiment, the aforementioned computer-readable storage medium may include, but is not limited to, various media capable of storing computer programs, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard disk, magnetic disk, or optical disk.

[0122] Specific examples in this embodiment can be found in the examples described in the above embodiments and exemplary implementations, and will not be repeated here.

[0123] Embodiments of this application also provide an electronic device including a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the steps in any of the above method embodiments.

[0124] Optionally, in this embodiment, the processor can be configured to perform the following steps via a computer program:

[0125] S1, when the target vehicle triggers the crab mode, determine the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value of the target vehicle;

[0126] S2, obtain the target yaw angle of the target vehicle, and determine the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle;

[0127] S3, determine the target rear wheel angle value of the target vehicle based on the feedforward rear wheel angle value and the feedback rear wheel angle value.

[0128] In one exemplary embodiment, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor and the input / output device is connected to the processor.

[0129] Embodiments of this application also provide a computer program product, which includes a computer program that, when executed by a processor, implements the steps in any of the above method embodiments.

[0130] Embodiments of this application also provide another computer program product, including a non-volatile computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in any of the above method embodiments.

[0131] Embodiments of this application also provide a computer program that includes computer instructions stored in a computer-readable storage medium; a processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the steps in any of the above method embodiments.

[0132] Specific examples in this embodiment can be found in the examples described in the above embodiments and exemplary implementations, and will not be repeated here.

[0133] Obviously, those skilled in the art should understand that the modules or steps of this application described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented here, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, this application is not limited to any particular combination of hardware and software.

[0134] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining the rear wheel steering angle value, characterized in that, include: When the target vehicle triggers the crab mode, the feedforward rear wheel angle value of the target vehicle is determined based on the front wheel angle value of the target vehicle. Obtain the target yaw angle of the target vehicle, and determine the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle; The target rear wheel angle value of the target vehicle is determined based on the feedforward rear wheel angle value and the feedback rear wheel angle value.

2. The method for determining the rear wheel steering angle value according to claim 1, characterized in that, Determining the feedforward rear wheel steering angle of the target vehicle based on the front wheel steering angle includes: Determine the gain value of the yaw rate of the target vehicle; The feedforward rear wheel steering angle is determined based on the gain value of the yaw rate and the front wheel steering angle value.

3. The method for determining the rear wheel steering angle value according to claim 1, characterized in that, Determining the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle includes: Determine the desired yaw angle of the target vehicle, and determine the deviation between the desired yaw angle and the target yaw angle; The deviation value is calculated based on the feedback control algorithm to obtain the feedback rear wheel steering angle value.

4. The method for determining the rear wheel steering angle value according to claim 1, characterized in that, Determining the target rear wheel steering angle value of the target vehicle based on the feedforward rear wheel steering angle value and the feedback rear wheel steering angle value includes: The feedforward rear wheel angle value and the feedback rear wheel angle value are summed to obtain the base rear wheel angle value; The target minimum rear wheel steering angle value corresponding to the target vehicle speed is determined based on the wheel steering dead zone curve of the target vehicle, wherein the horizontal axis of the wheel steering dead zone curve is used to indicate the vehicle speed of the target vehicle, and the vertical axis is used to indicate the minimum rear wheel steering angle value. The target rear wheel angle value is determined based on the target minimum rear wheel angle value and the base rear wheel angle value.

5. The method for determining the rear wheel steering angle value according to claim 4, characterized in that, Determining the target rear wheel steering angle value based on the target minimum rear wheel steering angle value and the base rear wheel steering angle value includes: Determine the first relationship between the target minimum rear wheel steering angle value and the base rear wheel steering angle value; If the first size relationship indicates that the base rear wheel steering angle value is less than the target minimum rear wheel steering angle value, the target rear wheel steering angle value is determined to be the target value; If the first size relationship indicates that the base rear wheel steering angle value is greater than or equal to the target minimum rear wheel steering angle value, the base rear wheel steering angle value is determined to be the target rear wheel steering angle value.

6. The method for determining the rear wheel steering angle value according to claim 4, characterized in that, Determining the target rear wheel steering angle value of the target vehicle based on the feedforward rear wheel steering angle value and the feedback rear wheel steering angle value includes: Determine a second relationship between the target limit value of the rear wheel steering angle of the target vehicle and the base rear wheel steering angle value; If the second size relationship indicates that the base rear wheel steering angle value is less than or equal to the target amplitude limit value, the base rear wheel steering angle value is determined to be the target rear wheel steering angle value; if the second size relationship indicates that the base rear wheel steering angle value is greater than the target amplitude limit value, the target amplitude limit value is determined to be the target rear wheel steering angle value.

7. The method for determining the rear wheel steering angle value according to claim 6, characterized in that, Before determining the second magnitude relationship between the target limit value of the rear wheel steering angle of the target vehicle and the base rear wheel steering angle value, the method further includes: A first limit value for the rear wheel steering angle is determined, and a second limit value for the rear wheel steering angle corresponding to the target vehicle speed is determined based on the limit value curve of the target vehicle, wherein the horizontal axis of the limit value curve is used to indicate the vehicle speed of the target vehicle, and the vertical axis is used to indicate the limit value. If the first limiting value is less than or equal to the second limiting value, the first limiting value is determined to be the target limiting value; If the first limiting value is greater than the second limiting value, the second limiting value is determined to be the target limiting value.

8. The method for determining the rear wheel steering angle value according to claim 1, characterized in that, Obtaining the target yaw angle of the target vehicle includes: The first yaw angle of the target vehicle is determined based on the yaw rate of the target vehicle, and the second yaw angle of the target vehicle is determined based on the lane line information of the target vehicle; the first yaw angle and the second yaw angle are weighted and summed to determine the target yaw angle.

9. The method for determining the rear wheel steering angle value according to claim 1, characterized in that, Determining the second yaw angle of the target vehicle based on the lane line information of the target vehicle includes: The lateral displacement rate of the target vehicle is determined based on the lane line information; The lateral displacement rate of change is calculated based on the target formula to obtain the second yaw angle, wherein the target formula includes: Yaw2 = tan -1 C1 and Yaw2 are the second yaw angles, and C1 is the rate of change of the lateral displacement.

10. The method for determining the rear wheel steering angle value according to claim 1, characterized in that, Before determining the feedforward rear wheel steering angle of the target vehicle based on the front wheel steering angle value, the process includes: Obtain the steering wheel angle value of the target vehicle and the transmission ratio of the steering system of the target vehicle; The front wheel angle value is determined based on the steering wheel angle value and the transmission ratio.

11. The method for determining the rear wheel steering angle value according to claim 1, characterized in that, Before determining the feedforward rear wheel steering angle of the target vehicle based on the front wheel steering angle value of the target vehicle, the method further includes: The crab mode is triggered when preset conditions are met, including: receiving a trigger command from the target object, determining that the front wheel angle of the target vehicle is less than the target limit value of the target vehicle, the front wheel steering and rear wheel steering of the target vehicle are fault-free, the target function of the target vehicle is not activated, and the target speed of the target vehicle is less than the preset speed.

12. A device for determining the rear wheel steering angle, characterized in that, include: The first determining module is used to determine the feedforward rear wheel angle value of the target vehicle based on the front wheel angle value of the target vehicle when the target vehicle triggers the crab mode; The second determining module is used to obtain the target yaw angle of the target vehicle and determine the feedback rear wheel steering angle value of the target vehicle based on the target yaw angle. The third determining module is used to determine the target rear wheel angle value of the target vehicle based on the feedforward rear wheel angle value and the feedback rear wheel angle value.

13. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein the program, when executed, performs the method described in any one of claims 1 to 11.

14. An electronic device comprising a memory and a processor, characterized in that, The memory stores a computer program, and the processor is configured to execute the method described in any one of claims 1 to 11 through the computer program.

Images