Rear wheel steering and EPB coordinated braking deceleration increasing method and device

Abstract

The invention discloses a rear wheel steering and EPB cooperative braking deceleration increasing method, device and equipment and a medium. In the vehicle running process, when the EPB function of an electronic parking brake system is started, an EPB is controlled to apply basic braking torque to rear wheels, and larger target braking torque is applied to a single target rear wheel; yawing torque generated by the target braking torque to the vehicle is determined; according to the yawing moment, calculating a rear wheel target steering angle required for generating a reverse yawing moment for counteracting the yawing moment; and controlling rear wheels of the vehicle to steer according to the rear wheel target steering angle, so that the braking deceleration of the EPB is obviously improved on the premise that the stability of the vehicle is not reduced, the braking performance of the whole vehicle is improved, and the safety and the stability of vehicle driving are enhanced.

Description

Technical Field

[0001] The present application relates to the field of vehicle control technology, and in particular to a method, device, equipment and medium for improving braking deceleration by coordinating rear-wheel steering with EPB. Background Art

[0002] In modern automotive braking systems, the electronic parking brake (EPB) system is a crucial auxiliary braking method, widely used across various vehicle models. The EPB system's primary function is to apply the parking brake when the vehicle is parked to prevent it from sliding. With the advancement of autonomous driving technology and the increasing demand for vehicle safety, the use of EPB systems in emergency braking and redundant braking is becoming increasingly important.

[0003] The EPB system generates braking force by driving the caliper with an electric motor to clamp the rear wheel brake disc. During vehicle driving, the EPB system can also be used for auxiliary braking, especially when the service brake system fails or redundant braking is required. In order to prevent tire locking and vehicle skidding, the EPB system usually controls the tire slip rate within a certain range (such as within 10%). For example, on an asphalt road, when braking causes the rear wheel to have a 10% slip rate, the vehicle deceleration is about 3m / s. 2 .

[0004] In case of emergency braking, 3m / s 2 The deceleration rate may not be sufficient to meet vehicle safety requirements. Higher deceleration is particularly necessary during high-speed driving or emergency avoidance. Increasing braking force increases rear wheel slip, reducing vehicle stability and potentially causing dangerous situations such as tailspin. Therefore, typical vehicle designs limit tire slip during EPB braking to less than 10%, limiting the increase in braking deceleration.

[0005] Existing EPB systems have significant deficiencies in braking deceleration and vehicle stability, failing to meet the high safety and reliability requirements of modern vehicles. Therefore, how to improve the braking deceleration of EPB systems while ensuring vehicle stability is a technical issue that needs to be addressed urgently. Summary of the Invention

[0006] The present application provides a method, device, equipment and medium for improving braking deceleration by coordinating rear-wheel steering and EPB, which can solve the problems existing in the prior art such as insufficient braking deceleration caused by tire slip rate control limitation of the electronic parking brake (EPB) system in emergency braking situations, as well as vehicle stability problems that may be caused when increasing braking force.

[0007] In a first aspect, an embodiment of the present application provides a method for improving braking deceleration by coordinating rear-wheel steering with EPB, the method comprising: During vehicle operation, when the EPB function of the electronic parking brake system is activated, the EPB is controlled to apply a basic braking torque to the rear wheels and a larger target braking torque to a single target rear wheel; determining a yaw moment generated by the target braking torque on the vehicle; calculating, based on the yaw moment, a target rear wheel steering angle required to generate a counter yaw moment for offsetting the yaw moment; The rear wheels of the vehicle are controlled to steer according to the rear wheel target steering angle.

[0008] In combination with the first aspect, in one embodiment, calculating, based on the yaw moment, a target rear wheel steering angle required to generate a counter yaw moment for offsetting the yaw moment includes: Taking the negative value of the yaw moment as the reverse yaw moment; The reverse yaw moment is divided by the rear wheel cornering stiffness of the vehicle and the distance from the center of gravity to the rear axle in sequence to obtain the rear wheel target steering angle.

[0009] In combination with the first aspect, in one embodiment, controlling the rear wheels of the vehicle to steer according to the rear wheel target steering angle further includes: monitoring an actual yaw rate of the vehicle; Calculating a yaw rate difference between the actual yaw rate and the target yaw rate; When the absolute value of the yaw rate difference is greater than a preset difference threshold, the rear wheel target steering angle or the target braking torque is adjusted through PID control with the yaw rate difference being 0 as a target.

[0010] In combination with the first aspect, in one embodiment, adjusting the rear wheel target steering angle or the target braking torque through PID control includes: Taking the yaw rate difference as 0 as a target, adjusting the rear wheel target steering angle through PID control; When the rear wheel target steering angle reaches a maximum steering angle and the absolute value of the yaw rate difference is still greater than a preset difference threshold, the target braking torque is adjusted through PID control with the yaw rate difference being 0 as a target.

[0011] In combination with the first aspect, in one embodiment, before controlling the EPB to apply a larger target braking torque to the single target rear wheel, the method further includes: Determining a limit yaw moment that can be generated by the target rear wheel when the target rear wheel is at a preset percentage maximum turning angle; Calculating a corresponding extreme limiting torque according to the extreme yaw moment; The smaller one between the limit braking torque of the electrically controlled brake and the maximum braking torque of the EPB is taken as the target braking torque.

[0012] In combination with the first aspect, in an implementation, the method further includes: obtaining the adhesion coefficients of the road surfaces on which the rear wheels are located; taking the rear wheel with the highest adhesion coefficient of the road surface as the target rear wheel.

[0013] In combination with the first aspect, in an implementation, the method further includes: multiplying the target braking torque by one-half of the wheel track of the rear wheel to obtain the yaw moment.

[0014] In a second aspect, an embodiment of the present application provides a rear wheel steering and EPB coordinated braking deceleration enhancement device, which includes: a control module configured to, during operation of a vehicle, control an EPB system to apply a basic braking torque to the rear wheels and a larger target braking torque to a target rear wheel when an EPB function is started; a determination module configured to determine a yaw moment generated by the target braking torque on the vehicle; a calculation module configured to calculate a target rear wheel steering angle required to generate a reverse yaw moment to offset the yaw moment according to the yaw moment; a steering module configured to control the rear wheels of the vehicle to steer according to the target rear wheel steering angle.

[0015] In a third aspect, an embodiment of the present application provides a rear wheel steering and EPB coordinated braking deceleration enhancement device, which includes a processor, a memory, and a rear wheel steering and EPB coordinated braking deceleration enhancement program stored in the memory and executable by the processor, wherein the rear wheel steering and EPB coordinated braking deceleration enhancement program, when executed by the processor, implements the steps of the rear wheel steering and EPB coordinated braking deceleration enhancement method according to any one of the above aspects.

[0016] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a rear wheel steering and EPB coordinated braking deceleration enhancement program, wherein the rear wheel steering and EPB coordinated braking deceleration enhancement program, when executed by a processor, implements the steps of the rear wheel steering and EPB coordinated braking deceleration enhancement method according to any one of the above aspects.

[0017] The beneficial effects of the technical solutions provided in the embodiments of the present application include: During vehicle operation, when the EPB function of the electronic parking brake system is activated, the EPB is controlled to apply a basic braking torque to the rear wheels and a larger target braking torque to a single target rear wheel; the yaw moment generated by the target braking torque on the vehicle is determined; based on the yaw moment, the target rear wheel steering angle required to generate a reverse yaw moment for offsetting the yaw moment is calculated; and the rear wheels of the vehicle are controlled to steer according to the target rear wheel steering angle. This achieves full utilization of the vehicle actuator's capabilities without increasing additional hardware costs, significantly improves the EPB braking deceleration without reducing vehicle stability, thereby improving the braking performance of the entire vehicle and enhancing the safety and stability of vehicle driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of an embodiment of a method for improving braking deceleration by coordinating rear-wheel steering with EPB in this application; Figure 2 This is a functional module diagram of an embodiment of a braking deceleration enhancement device for rear-wheel steering and EPB coordination in this application; Figure 3 This is a schematic diagram of the hardware structure of the braking deceleration enhancement device for rear-wheel steering and EPB coordination involved in the embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0021] In a first aspect, an embodiment of the present application provides a method for improving braking deceleration by coordinating rear-wheel steering with EPB.

[0022] In one embodiment, referring to Figure 1 , Figure 1 This is a flow chart of the first embodiment of the method for improving the braking deceleration by coordinating rear wheel steering and EPB in this application. Figure 1 As shown, the braking deceleration improvement method of the rear wheel steering and EPB coordinated includes: Step S101: During vehicle operation, when the electronic parking brake (EPB) function is activated, the EPB is controlled to apply a basic braking torque to the rear wheels and a larger target braking torque to a single target rear wheel.

[0023] It's worth noting that the EPB function can be activated by the driver operating the EPB button or automatically by the vehicle's automated driving system in an emergency. When the EPB function is activated, the vehicle's ECU controls the EPB system to apply a base braking torque to both rear wheels. This base braking torque is pre-calculated based on factors such as the vehicle's current speed, road conditions, and vehicle load. It generally provides stable braking, but is insufficient for maximum deceleration.

[0024] In one embodiment, controlling the EPB system to apply a larger target braking torque to a single target rear wheel also includes the step of selecting the target rear wheel, specifically including: obtaining the adhesion coefficient of the road surface on which each rear wheel is located; and selecting the rear wheel with the highest adhesion coefficient on the road surface as the target rear wheel.

[0025] For example, the ECU detects the adhesion coefficient of the road surface for each rear wheel. Adhesion coefficients can be measured in real time using the vehicle's sensor systems (such as wheel speed sensors and accelerometers). Assuming the left rear wheel has an adhesion coefficient of 0.7 and the right rear wheel has an adhesion coefficient of 0.8, the ECU selects the right rear wheel, with the higher adhesion coefficient, as the target rear wheel. If the left and right rear wheels have the same adhesion coefficient on a uniform surface, either wheel can be selected. However, if the vehicle is traveling on a split surface, such as asphalt on one side and ice on the other, the tire with the higher adhesion coefficient can be selected to apply a greater braking torque.

[0026] Selecting the rear wheel with the highest road adhesion coefficient as the target rear wheel maximizes braking effectiveness and ensures vehicle stability. By applying a larger target braking torque to the tire with the higher adhesion coefficient, the maximum adhesion between that tire and the road is fully utilized, providing greater deceleration during emergency braking while minimizing the risk of tire lock and vehicle loss of control. This not only improves braking efficiency but also enhances vehicle safety and reliability on complex road conditions.

[0027] In one embodiment, before controlling the EPB system to apply a larger target braking torque to a single target rear wheel, the method further includes: determining a limit yaw moment that can be generated by the target rear wheel at a preset percentage of maximum turning angle; calculating a corresponding extreme limiting torque based on the limit yaw moment; and using the smaller of the extreme limiting torque and the maximum braking torque of the EPB system as the target braking torque.

[0028] For example, the preset percentage in this embodiment is 80%. For example, if the target maximum rear wheel turning angle is 10 degrees, and the preset percentage is 80%, the corresponding turning angle is 8 degrees. Using the vehicle dynamics model, the limit yaw moment that can be generated by the target rear wheel at an 8-degree turning angle can be calculated. Dividing the limit yaw moment by half the rear wheel track yields the maximum braking torque. The ECU then obtains the maximum braking torque of the EPB system and selects the smaller of the maximum braking torque and the EPB system's maximum braking torque as the target braking torque.

[0029] This embodiment avoids the risk of tire locking or vehicle loss of control due to excessive braking torque by selecting the smaller of the target rear wheel's extreme limit torque and the EPB system's maximum braking torque as the target braking torque, thereby ensuring the stability and controllability of the vehicle during braking.

[0030] Step S102: Determine the yaw moment generated by the target braking torque on the vehicle.

[0031] It is worth noting that when EPB applies a larger target braking torque to a single target rear wheel, there is a braking torque difference between the target rear wheel and the non-target rear wheel, which causes the vehicle to generate a yaw moment. The yaw moment is obtained by multiplying the target braking torque by half the rear wheel track. The formula is: Mz = Fx * (tr / 2) Where Mz is the yaw moment, Fx is the target braking torque, and tr is the rear wheel track of the vehicle.

[0032] Step S103: Calculate, based on the yaw moment, a target rear wheel steering angle required to generate a counter yaw moment for offsetting the yaw moment.

[0033] Specifically, the negative value of the yaw moment is used as the reverse yaw moment: Mzr = -Mz Where Mzr is the reverse yaw moment.

[0034] The reverse yaw moment is divided by the rear wheel cornering stiffness of the vehicle and the distance from the center of gravity to the rear axle in sequence to obtain the rear wheel target steering angle:

[0035] in, is the target steering angle of the rear wheels, is the rear wheel cornering stiffness, and b is the distance from the center of gravity to the rear axle.

[0036] Explanatory, the tire slip angle αr of the vehicle's rear wheels mainly consists of two parts. One part is the geometric slip angle caused by the steering angle, which is directly introduced by the rear wheel rotation δr. The other part is the slip angle caused by the vehicle's motion. The vehicle's yaw motion (rotation around the center of gravity) and lateral motion will cause the actual tire speed direction to be different from the tire pointing direction, resulting in an additional slip angle.

[0037] According to the linear two-degree-of-freedom vehicle model: αr≈δr- (ay-r×b) / ax Among them, αr is the tire slip angle, δr is the rear wheel turning angle, ay is the lateral velocity at the center of gravity of the vehicle, r is the vehicle yaw rate (Yaw Rate), ax is the vehicle longitudinal speed (forward speed), and b is the distance from the center of gravity to the rear axle.

[0038] Under the assumptions of small angles, linear tire characteristics, steady state or quasi-steady state, the corresponding relationship between δr and Mzr can be established: Ignoring the slip angle caused by vehicle motion, αr≈δr. When the tire slips, the cornering force generated is linearly related to the slip angle, and the rear wheel cornering force can be obtained as: Fyr≈Cαr*δr, where Fyr is the tire cornering force. is the rear wheel cornering stiffness. The yaw moment generated by rear-wheel steering can be deduced as: Mzr ≈ Fyr*b ≈ (Cαr *δr) *b = Cαr*b*δr. Therefore, the target rear wheel steering angle can be calculated based on the reverse yaw moment, the vehicle's rear wheel cornering stiffness, and the distance from the center of gravity to the rear axle.

[0039] Step S104: Control the rear wheels of the vehicle to steer according to the rear wheel target steering angle.

[0040] As a preferred embodiment, controlling the rear wheels of the vehicle to steer according to the target rear wheel steering angle further includes: the ECU monitoring the vehicle's actual yaw rate ω in real time via the vehicle's sensor system (e.g., a yaw rate sensor), and calculating a yaw rate difference Δω between the actual yaw rate ω and a target yaw rate ω0. The target yaw rate ω0 can be set based on vehicle control requirements. For example, in this embodiment, the target yaw rate ω0 can be set to 0, meaning that the vehicle should remain stable and not yaw during braking.

[0041] When the absolute value of the yaw rate difference is greater than a preset difference threshold, it indicates that the current vehicle stability is low. The rear wheel target steering angle or the target braking torque is adjusted through PID control with the yaw rate difference being 0 as the target.

[0042] Specifically, when the absolute value of the yaw rate difference exceeds a preset difference threshold, the target rear wheel steering angle is adjusted through PID control, with the yaw rate difference set to zero. When the target rear wheel steering angle reaches its maximum and the absolute value of the yaw rate difference remains above the preset difference threshold, the target braking torque is adjusted through PID control, with the yaw rate difference set to zero, to ensure vehicle stability. By monitoring the vehicle's yaw rate in real time and implementing PID control on the rear wheel target steering angle or target braking torque, vehicle stability and safety are ensured during emergency braking. Even on complex road conditions, the vehicle maintains excellent driving stability, avoiding the risk of loss of control due to excessive yaw torque.

[0043] The embodiment of the present application provides a method for improving braking deceleration by combining rear-wheel steering with EPB. By applying a larger target braking torque to a single target rear wheel through the EPB system, the vehicle's braking deceleration is significantly increased. In emergency braking situations, the vehicle can reduce speed more quickly and shorten braking distances, thereby improving driving safety. Precise steering control of the rear wheels by the rear-wheel steering (RWS) system offsets the yaw moment generated by the increased braking torque, ensuring vehicle stability during braking. Even under complex road conditions, the vehicle can avoid dangerous conditions such as tailspin and skidding, improving driving stability and controllability. Furthermore, the rear wheel with the highest adhesion coefficient is selected as the target rear wheel based on the adhesion coefficient of the road surface it is on, ensuring maximum braking torque across a wide range of road conditions and enhancing the vehicle's adaptability and safety in complex road conditions. Closed-loop control and real-time adjustments ensure system stability and reliability under various operating conditions. Even in extreme situations, the system automatically adjusts to maintain vehicle stability and safety, enhancing overall system performance. This system is implemented based on the existing EPB and RWS systems of existing vehicles, eliminating the need for additional hardware and reducing costs and system complexity. Through software optimization and improvement of control strategy, significant performance improvement has been achieved, with high cost performance.

[0044] On the second aspect, the embodiment of the present application also provides a braking deceleration enhancement device that cooperates with rear wheel steering and EPB.

[0045] In one embodiment, referring to Figure 2 , Figure 2 This is a functional module diagram of an embodiment of a braking deceleration enhancement device for rear wheel steering and EPB coordination in this application. Figure 2 As shown, the braking deceleration enhancement device that cooperates with the rear wheel steering and EPB includes: a control module configured to control the EPB system to apply a base braking torque to the rear wheels and apply a larger target braking torque to a single target rear wheel when the EPB function is activated during vehicle operation; a determination module, configured to determine a yaw moment generated by the target braking moment on the vehicle; a calculation module, configured to calculate, based on the yaw moment, a target rear wheel steering angle required to generate a counter yaw moment for offsetting the yaw moment; A steering module is used to control the rear wheels of the vehicle to steer according to the rear wheel target steering angle.

[0046] Furthermore, in one embodiment, the calculation module is further configured to: Taking the negative value of the yaw moment as the reverse yaw moment; The reverse yaw moment is divided by the rear wheel cornering stiffness of the vehicle and the distance from the center of gravity to the rear axle in sequence to obtain the rear wheel target steering angle.

[0047] Furthermore, in one embodiment, the device is also used for: monitoring an actual yaw rate of the vehicle; Calculating a yaw rate difference between the actual yaw rate and the target yaw rate; When the absolute value of the yaw rate difference is greater than a preset difference threshold, the rear wheel target steering angle or the target braking torque is adjusted through PID control with the yaw rate difference being 0 as a target.

[0048] Furthermore, in one embodiment, the device is also used for: Taking the yaw rate difference as 0 as a target, adjusting the rear wheel target steering angle through PID control; When the rear wheel target steering angle reaches a maximum steering angle and the absolute value of the yaw rate difference is still greater than a preset difference threshold, the target braking torque is adjusted through PID control with the yaw rate difference being 0 as a target.

[0049] Furthermore, in one embodiment, the control module is further configured to: Determining a limit yaw moment that can be generated by the target rear wheel when the target rear wheel is at a preset percentage maximum turning angle; Calculating a corresponding extreme limiting torque according to the extreme yaw moment; The smaller one between the extreme limit torque and the maximum braking torque of the EPB is used as the target braking torque.

[0050] Furthermore, in one embodiment, the control module is further configured to: Obtain the adhesion coefficient of the road surface on each rear wheel; The rear wheel with the highest adhesion coefficient on the road surface is used as the target rear wheel.

[0051] Furthermore, in one embodiment, the determining module is further configured to: The yaw moment is obtained by multiplying the target braking torque by half of the rear wheel track.

[0052] Among them, the functional implementation of each module in the above-mentioned rear-wheel steering and EPB coordinated braking deceleration improvement device corresponds to the various steps in the above-mentioned rear-wheel steering and EPB coordinated braking deceleration improvement method embodiment, and its functions and implementation processes will not be repeated here one by one.

[0053] On the third aspect, an embodiment of the present application provides a braking deceleration enhancement device that cooperates with rear-wheel steering and EPB. The braking deceleration enhancement device that cooperates with rear-wheel steering and EPB can be a vehicle control unit ECU, a vehicle computer, or other device with data processing capabilities.

[0054] Reference Figure 3 , Figure 3 This is a hardware structure diagram of the rear-wheel steering and EPB coordinated braking deceleration enhancement device involved in the embodiment of the present application. In the embodiment of the present application, the rear-wheel steering and EPB coordinated braking deceleration enhancement device may include a processor, a memory, a communication interface, and a communication bus.

[0055] The communication bus may be of any type and is used to interconnect the processor, memory, and communication interface.

[0056] Communication interfaces include input / output (I / O), physical, and logical interfaces, used to interconnect components within the rear-wheel steering and EPB-coordinated braking deceleration boosting device, as well as interfaces used to interconnect the rear-wheel steering and EPB-coordinated braking deceleration boosting device with other devices (such as other computing devices or user devices). Physical interfaces can include Ethernet, fiber optic, and ATM interfaces; user devices can include displays and keyboards.

[0057] The memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), and the like.

[0058] The processor can be a general-purpose processor, which can invoke the rear wheel turning and EPB cooperative braking deceleration enhancement program stored in the memory and execute the rear wheel turning and EPB cooperative braking deceleration enhancement method provided by the embodiments of the present application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the rear wheel turning and EPB cooperative braking deceleration enhancement program is invoked can refer to various embodiments of the rear wheel turning and EPB cooperative braking deceleration enhancement method of the present application, which will not be described here.

[0059] Those skilled in the art can understand that the hardware structure shown in the above-mentioned embodiments is not a limitation of the present application, and can include more or fewer components than those shown, or combine certain components, or different component arrangements. Figure 3 The hardware structure shown in the above-mentioned embodiments is not a limitation of the present application, and can include more or fewer components than those shown, or combine certain components, or different component arrangements.

[0060] In a fourth aspect, the embodiments of the present application further provide a computer readable storage medium.

[0061] The computer readable storage medium of the present application stores the rear wheel turning and EPB cooperative braking deceleration enhancement program, wherein when the rear wheel turning and EPB cooperative braking deceleration enhancement program is executed by the processor, the steps of the rear wheel turning and EPB cooperative braking deceleration enhancement method as described above are implemented.

[0062] The method implemented when the rear wheel turning and EPB cooperative braking deceleration enhancement program is executed can refer to various embodiments of the rear wheel turning and EPB cooperative braking deceleration enhancement method of the present application, which will not be described here.

[0063] It should be noted that the above-mentioned sequence numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0064] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0065] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0066] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0067] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0068] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform. 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, or the part that contributes to the existing technology, 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) as described above and includes a number of instructions for enabling a terminal device to execute the methods described in each embodiment of this application.

[0069] The above merely provides the preferred embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structure or equivalent flowchart transformation, or direct or indirect application in other related technical fields, which is made based on the contents of the present application specification and drawings, shall be included in the patent protection scope of the present application.

Claims

1. A method for improving braking deceleration by coordinating rear wheel steering with EPB, characterized in that: The method for improving braking deceleration by coordinating rear wheel steering with EPB includes: During vehicle operation, when the EPB function of the electronic parking brake system is activated, the EPB is controlled to apply a basic braking torque to the rear wheels and a larger target braking torque to a single target rear wheel; determining a yaw moment generated by the target braking torque on the vehicle; calculating, based on the yaw moment, a target rear wheel steering angle required to generate a counter yaw moment for offsetting the yaw moment; The rear wheels of the vehicle are controlled to steer according to the rear wheel target steering angle.

2. The method for improving braking deceleration by coordinating rear-wheel steering and EPB according to claim 1, characterized in that: Calculating, based on the yaw moment, a target rear wheel steering angle required to generate a counter yaw moment for offsetting the yaw moment, comprising: Taking the negative value of the yaw moment as the reverse yaw moment; The reverse yaw moment is divided by the rear wheel cornering stiffness of the vehicle and the distance from the center of gravity to the rear axle in sequence to obtain the rear wheel target steering angle.

3. The method for improving braking deceleration by coordinating rear-wheel steering and EPB according to claim 1, characterized in that: Controlling the rear wheels of the vehicle to steer according to the rear wheel target steering angle further includes: monitoring an actual yaw rate of the vehicle; Calculating a yaw rate difference between the actual yaw rate and the target yaw rate; When the absolute value of the yaw rate difference is greater than a preset difference threshold, the rear wheel target steering angle or the target braking torque is adjusted through PID control with the yaw rate difference being 0 as a target.

4. The method for improving braking deceleration by coordinating rear wheel steering with EPB as claimed in claim 3, characterized in that: Adjusting the rear wheel target steering angle or the target braking torque through PID control includes: Taking the yaw rate difference as 0 as a target, adjusting the rear wheel target steering angle through PID control; When the rear wheel target steering angle reaches a maximum steering angle and the absolute value of the yaw rate difference is still greater than a preset difference threshold, the target braking torque is adjusted through PID control with the yaw rate difference being 0 as a target.

5. The method for improving braking deceleration by coordinating rear wheel steering with EPB as claimed in claim 1, characterized in that: Before controlling the EPB to apply a larger target braking torque to a single target rear wheel, the following steps are also included: determining a limit yaw moment that can be generated by the target rear wheel when the target rear wheel turns at a preset percentage maximum angle; Calculating a corresponding extreme limiting torque according to the extreme yaw moment; The smaller one between the extreme limit torque and the maximum braking torque of the EPB is used as the target braking torque.

6. The method for improving braking deceleration by coordinating rear wheel steering with EPB as claimed in claim 1, characterized in that: Controlling the EPB to apply a larger target braking torque to a single target rear wheel also includes: Obtain the adhesion coefficient of the road surface on each rear wheel; The rear wheel with the highest adhesion coefficient on the road surface is used as the target rear wheel.

7. The method for improving braking deceleration by coordinating rear-wheel steering with EPB as claimed in claim 1, characterized in that: Determining the yaw moment generated by the target braking torque on the vehicle further includes: The yaw moment is obtained by multiplying the target braking torque by half of the rear wheel track.

8. A braking deceleration enhancement device that cooperates with rear wheel steering and EPB, characterized in that: The rear wheel steering and EPB coordinated braking deceleration enhancement device includes: a control module configured to control the EPB system to apply a base braking torque to the rear wheels and apply a larger target braking torque to a single target rear wheel when the EPB function is activated during vehicle operation; a determination module, configured to determine a yaw moment generated by the target braking moment on the vehicle; a calculation module, configured to calculate, based on the yaw moment, a target rear wheel steering angle required to generate a counter yaw moment for offsetting the yaw moment; A steering module is used to control the rear wheels of the vehicle to steer according to the rear wheel target steering angle.

9. A braking deceleration enhancement device that cooperates with rear wheel steering and EPB, characterized in that: The rear-wheel steering and EPB coordinated braking deceleration enhancement device includes a processor, a memory, and a rear-wheel steering and EPB coordinated braking deceleration enhancement program stored on the memory and executable by the processor, wherein when the rear-wheel steering and EPB coordinated braking deceleration enhancement program is executed by the processor, the steps of the rear-wheel steering and EPB coordinated braking deceleration enhancement method as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a braking deceleration improvement program for coordinated rear-wheel steering and EPB, wherein when the braking deceleration improvement program for coordinated rear-wheel steering and EPB is executed by the processor, the steps of the braking deceleration improvement method for coordinated rear-wheel steering and EPB as described in any one of claims 1 to 7 are implemented.

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