Vehicle braking system and control unit and control method thereof

Abstract

The invention provides a vehicle braking system and a control unit and a control method thereof. The vehicle braking system is suitable for providing braking control for a vehicle when a main braking system of the vehicle fails. The control unit includes: a receiving module configured to receive wheel speed information including a left front wheel speed and a right front wheel speed coupled with a front axle of the vehicle, and a left rear wheel speed and a right rear wheel speed coupled with a rear axle of the vehicle; the calculation module is configured to calculate the slip rate of each wheel based on the wheel speed of each wheel; a comparison module configured to compare a larger one of the slip rate of the left front wheel and the slip rate of the right front wheel with a front axle reference slip rate, and to compare a larger one of the slip rate of the left rear wheel and the slip rate of the right rear wheel with a rear axle reference slip rate; and the dynamic adjusting module is configured to dynamically adjust the front axle target braking force and the rear axle target braking force of the vehicle based on the comparison result.

Description

Technical Field

[0001] The present invention generally relates to the technical field of vehicle braking. Specifically, the present invention relates to a vehicle braking system and a control unit thereof. The present invention also relates to a corresponding braking control method. Background Art

[0002] According to the current design requirements of vehicle braking systems, a backup function is required in case the main braking system fails. Therefore, one solution is to provide a redundant braking system for the vehicle. However, due to factors such as system complexity and cost, the vehicle braking provided by the redundant braking system when the vehicle is in a backup state often has poor performance. Summary of the invention

[0003] In view of the above problems in the prior art, an embodiment of the present invention provides a solution for providing high-performance braking control for a vehicle when a main braking system of the vehicle fails.

[0004] According to one aspect of the present invention, a control unit for vehicle braking is provided, which is suitable for providing braking control for the vehicle when the main braking system of the vehicle fails. The control unit includes: a receiving module, configured to receive wheel speed information, which includes the left front wheel speed and the right front wheel speed coupled to the front axle of the vehicle, and the left rear wheel speed and the right rear wheel speed coupled to the rear axle of the vehicle; a calculation module, configured to calculate the slip rate of each wheel based on the wheel speed of each wheel; a comparison module, configured to compare the larger of the slip rate of the left front wheel and the slip rate of the right front wheel with the reference slip rate of the front axle, and compare the larger of the slip rate of the left rear wheel and the slip rate of the right rear wheel with the reference slip rate of the rear axle; and a dynamic adjustment module, configured to dynamically adjust the front axle target braking force and the rear axle target braking force of the vehicle based on the comparison result. The dynamic adjustment includes: reducing the target braking force of the front axle when the larger of the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the reference slip rate of the front axle; reducing the target braking force of the rear axle when the larger of the slip rate of the left rear wheel and the slip rate of the right rear wheel is greater than the reference slip rate of the rear axle; increasing the target braking force of the front axle when the larger of the slip rate of the left front wheel and the slip rate of the right front wheel is less than the reference slip rate of the front axle; and increasing the target braking force of the rear axle when the larger of the slip rate of the left rear wheel and the slip rate of the right rear wheel is less than the reference slip rate of the rear axle.

[0005] According to another aspect of the present invention, a vehicle braking system is provided, which includes: a main braking system for providing four-wheel independent control braking; and an auxiliary braking system for providing split-axle control braking when the main braking system fails. The auxiliary braking system includes: a wheel speed sensor for sensing the wheel speed of the left front wheel and the right front wheel coupled to the front axle of the vehicle, and the wheel speed of the left rear wheel and the right rear wheel coupled to the rear axle of the vehicle; and a control unit as described above, configured to: dynamically adjust the front axle target braking force and the rear axle target braking force of the vehicle based on the comparison result. The auxiliary braking system also includes a first hydraulic linear valve, configured to perform a valve opening corresponding to the front axle target braking force to achieve the adjustment of the slip ratio of the left front wheel and the right front wheel; and a second hydraulic linear valve, configured to perform a valve opening corresponding to the rear axle target braking force to achieve the adjustment of the slip ratio of the left rear wheel and the right rear wheel.

[0006] According to another aspect of the present invention, a vehicle braking control method is provided, comprising: when a main braking system of a vehicle fails, receiving wheel speed information, which includes the left front wheel speed and the right front wheel speed coupled to the front axle of the vehicle, and the left rear wheel speed and the right rear wheel speed coupled to the rear axle of the vehicle; calculating the slip rate of each wheel based on the wheel speed of each wheel; comparing the larger of the slip rate of the left front wheel and the slip rate of the right front wheel with a front axle reference slip rate, and comparing the larger of the slip rate of the left rear wheel and the slip rate of the right rear wheel with a rear axle reference slip rate; and dynamically adjusting the front axle target braking force and the rear axle target braking force of the vehicle based on the comparison result. The dynamic adjustment includes: when the larger of the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the reference slip rate of the front axle, reducing the target braking force of the front axle; when the larger of the slip rate of the left rear wheel and the slip rate of the right rear wheel is greater than the reference slip rate of the rear axle, reducing the target braking force of the rear axle; when the larger of the slip rate of the left front wheel and the slip rate of the right front wheel is less than the reference slip rate of the front axle, increasing the target braking force of the front axle; and when the larger of the slip rate of the left rear wheel and the slip rate of the right rear wheel is less than the reference slip rate of the rear axle, increasing the target braking force of the rear axle. Optionally, the method can be performed by the control unit as described above or the system as described above.

[0007] According to another aspect of the present invention, a machine-readable storage medium is provided, which contains executable instructions, which, when executed by one or more processors, enable the method described above to be performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic block diagram of a vehicle braking system according to an embodiment of the present invention.

[0009] Figure 2 is a flow chart of a vehicle braking control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0010] Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0011] Figure 1 A vehicle braking system 100 according to an embodiment of the present invention is schematically shown, hereinafter referred to as the braking system 100. The braking system 100 is mounted on a vehicle, and thus may also be referred to as a vehicle-mounted braking system.

[0012] See also Figure 1 , the braking system 100 includes two braking systems (redundant braking systems), namely, a main braking system 10 and an auxiliary braking system 20. The main braking system 10 can communicate with the auxiliary braking system 20 and exchange information so that each of them can promptly know the status of the other, for example, normal working state or failure state (for example, loss of electronic brake boost function, loss of control, loss of power, etc.). The embodiments of the present invention mainly relate to the braking control provided by the auxiliary braking system 20 in the event of failure of the main braking system 10. Under such braking control, the stability of the vehicle during braking is high and safety can be guaranteed.

[0013] The main brake system 10 can realize wheel-controlled braking, that is, during the vehicle braking process, each of the four wheels can be independently controlled.

[0014] The auxiliary brake system 20 can provide split-axle controlled braking when the main brake system fails, that is, it can independently control the front wheels (left front wheel and right front wheel) coupled to the front axle of the vehicle and the rear wheels (left rear wheel and right rear wheel) coupled to the rear axle of the vehicle.

[0015] Continue to see Figure 1 The auxiliary brake system 20 includes: a wheel speed sensor 21 , a control unit 22 , a first hydraulic linear valve 23 and a second hydraulic linear valve 24 .

[0016] The wheel speed sensor 21 may include four wheel speed sensors 211 ˜ 214 , which are respectively coupled to each of the four wheels so as to measure the wheel speed of each wheel and output the measured wheel speed information.

[0017] The control unit 22 calculates the slip rate of each wheel based on the wheel speed information measured by the wheel speed sensor, and dynamically adjusts the front axle target braking force and the rear axle target braking force of the vehicle based on the deviation of each wheel slip rate (i.e., the actual wheel slip rate) from the corresponding reference slip rate (the front axle reference slip rate and the rear axle reference slip rate), so that the deviated reference slip rate becomes or is as close as possible to the corresponding reference slip rate.

[0018] In one embodiment, the control unit 22 includes a receiving module 221, a calculation module 222, a comparison module 223, a dynamic adjustment module 224 and an allocation module 225. These modules can be implemented in hardware or software or a combination of software and hardware. For the hardware-implemented part, it can be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic units designed to perform their functions, or combinations thereof. For the software-implemented part, it can be implemented with the aid of microcodes, program codes or code segments, and they can also be stored in machine-readable storage media such as storage components.

[0019] It is to be understood that the naming of each module of the control unit 22 should be understood as a logical (functional) description, and should not be understood as a limitation of physical form or physical location. For example, these modules can be implemented on the same chip or circuit, or on different chips or circuits. In addition, each of these modules can be further divided into sub-modules. In addition, two or more of these modules can be combined into one module.

[0020] In one embodiment, the control unit 22 may be implemented as a memory and a processor. The memory contains instructions, which, when executed by the processor, enable the processor to perform a brake control strategy / brake control method according to an embodiment of the present invention.

[0021] It is worth noting that Figure 1 2 shows an example in which the control unit 22 is arranged in the auxiliary brake system 20. According to an embodiment of the present invention, the control unit 22 may also be arranged in other vehicle-mounted systems or a vehicle ECU or a VCU.

[0022] The first hydraulic linear valve 23 is coupled to the front axle of the vehicle, so that the braking of the left front wheel and the right front wheel can be controlled by manipulating the first hydraulic linear valve 23. The first hydraulic linear valve 23 can be implemented as a solenoid valve, and its control signal is a current signal corresponding to the target braking force of the front axle. The first hydraulic linear valve 23 is adjusted to a corresponding opening based on the current signal, thereby achieving braking control that meets the target braking force of the front axle.

[0023] Similarly, the second hydraulic linear valve 24 is coupled to the rear axle of the vehicle, so that the braking of the left and right front wheels can be controlled by manipulating the second hydraulic linear valve 24. The second hydraulic linear valve 24 can be implemented as a solenoid valve, and its control signal is a current signal corresponding to the target braking force of the front axle. The second hydraulic linear valve 24 is adjusted to a corresponding opening based on the control current, thereby achieving braking control that meets the target braking force of the rear axle.

[0024] The advantage of using a hydraulic linear valve is that the target braking force can be achieved quickly and accurately.

[0025] Figure 2 A braking control method 200 according to an embodiment of the present invention is shown. The method 200 can be executed by the control unit 22 or the braking system 100, so the above description of the control unit 22 and the braking system 100 also applies here.

[0026] In frame 210, the receiving module 221 receives wheel speed information. The wheel speed information includes the wheel speed of each wheel of the vehicle, that is, the left front wheel speed, the right front wheel speed, the left rear wheel speed and the right rear wheel speed. The left front wheel and the right front wheel are coupled to the front axle of the vehicle, and the left rear wheel and the right rear wheel are coupled to the rear axle of the vehicle. According to an embodiment of the present invention, the wheel speed sensor 21 can directly transmit the wheel speed information to the control unit 20, or transmit the wheel speed information to the control unit via the vehicle bus.

[0027] In block 220, the calculation module 222 calculates the slip rate of each wheel based on the received wheel speed information. For example, the calculation module 222 calculates the speed difference between the wheel speed of each wheel and the reference vehicle speed, and then calculates the ratio between the speed difference and the reference vehicle speed to obtain the slip rate of each wheel. It is understood that other methods or other expressions may be used to obtain the slip rate of each wheel, and the present invention is not limited thereto.

[0028] In block 230 , the comparison module 223 compares the calculated wheel slip ratios and the calculated wheel slip ratios with the front axle reference slip ratio or the rear axle reference slip ratio. Some embodiments of the comparison step of block 230 are described below.

[0029] In one embodiment, referring to block 231, the comparison module 223 compares the slip rate of the left front wheel with the slip rate of the right front wheel to obtain the larger slip rate or the slip rate difference between the two. In addition, the comparison module 223 compares the slip rate of the left rear wheel with the slip rate of the right rear wheel to obtain the larger slip rate or the slip rate difference between the two.

[0030] In another embodiment, referring to block 232, the comparison module 223 compares the slip rate of the left front wheel with the reference slip rate of the front axle to obtain a difference or ratio between the two. The comparison module 223 compares the slip rate of the right front wheel with the reference slip rate of the front axle to obtain a difference or ratio between the two. The comparison module 223 compares the slip rate of the left rear wheel with the reference slip rate of the rear axle to obtain a difference or ratio between the two. The comparison module 223 compares the slip rate of the right rear wheel with the reference slip rate of the rear axle to obtain a difference or ratio between the two.

[0031] In an embodiment of the present invention, the front axle reference slip rate can be understood as an ideal front axle slip rate. The rear axle reference slip rate can be understood as an ideal rear axle slip rate. The front axle reference slip rate and the rear axle reference slip rate are both predetermined, for example, the front axle reference slip rate and the rear axle reference slip rate are predetermined based on actual vehicle testing and / or model calculation. In addition, the front axle reference slip rate and the rear axle reference slip rate can be adjusted according to specific application scenarios, user needs (for example, the needs of vehicle manufacturers) and user preferences (for example, the driving preferences of end users).

[0032] In the embodiment of the present invention, the reference slip rate of the front axle and the reference slip rate of the rear axle are determined separately, and the two can be the same or different, and there is no special constraint relationship between the two.

[0033] In an embodiment of the present invention, the front axle reference slip rate can be implemented as a curve that varies with time. When comparing the slip rate of the left front wheel with the front axle reference slip rate, the curve of the slip rate of the left front wheel varying with time can be compared with the curve of the front axle reference slip rate. When comparing the slip rate of the right front wheel with the front axle reference slip rate, the curve of the slip rate of the right front wheel varying with time can be compared with the curve of the front axle reference slip rate. Similarly, the rear axle reference slip rate can be implemented as a curve that varies with time. When comparing the slip rate of the left rear wheel with the rear axle reference slip rate, the curve of the slip rate of the left rear wheel varying with time can be compared with the curve of the rear axle reference slip rate. When comparing the slip rate of the right rear wheel with the rear axle reference slip rate, the curve of the slip rate of the right rear wheel varying with time can be compared with the curve of the rear axle reference slip rate.

[0034] In box 240 , the dynamic adjustment module 224 dynamically adjusts the front axle target braking force and the rear axle target braking force based on the comparison result in box 230 to achieve vehicle stability during braking. Some embodiments of the dynamic adjustment step of box 240 are described below.

[0035] In one embodiment, referring to block 241 , the dynamic adjustment module 224 adjusts the front axle target braking force based on the larger of the slip ratio of the left front wheel and the slip ratio of the right front wheel, and adjusts the rear axle target braking force based on the larger of the slip ratio of the left rear wheel and the slip ratio of the right rear wheel.

[0036] For example, when the larger of the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the front axle reference slip rate, the front axle target braking force is reduced, with the result that both the slip rate of the left front wheel and the slip rate of the right front wheel are reduced. When the larger of the slip rate of the left rear wheel and the slip rate of the right rear wheel is greater than the rear axle reference slip rate, the rear axle target braking force is reduced, with the result that both the slip rate of the left rear wheel and the slip rate of the right rear wheel are reduced.

[0037] For example, when the larger of the slip ratio of the left front wheel and the slip ratio of the right front wheel is less than the reference slip ratio of the front axle, the target braking force of the front axle is increased, and as a result, both the slip ratio of the left front wheel and the slip ratio of the right front wheel are increased. When the larger of the slip ratio of the left rear wheel and the slip ratio of the right rear wheel is less than the reference slip ratio of the rear axle, the target braking force of the rear axle is increased, and as a result, both the slip ratio of the left rear wheel and the slip ratio of the right rear wheel are increased.

[0038] In this embodiment, when the larger of the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the front axle reference slip rate, the dynamic adjustment module 224 may also monitor the slip rate increase rate of the larger of the slip rate of the left front wheel and the slip rate of the right front wheel, and reduce the front axle target braking force faster as the slip rate increase rate increases. When the larger of the slip rate of the left rear wheel and the slip rate of the right rear wheel is greater than the rear axle reference slip rate, the dynamic adjustment module 224 may also monitor the slip rate increase rate of the larger of the slip rate of the left rear wheel and the slip rate of the right rear wheel, and reduce the rear axle target braking force faster as the slip rate increase rate increases.

[0039] Similarly, when the larger of the slip ratio of the left front wheel and the slip ratio of the right front wheel is less than the front axle reference slip ratio, the dynamic adjustment module 224 may also monitor the slip ratio reduction rate of the larger of the slip ratio of the left front wheel and the slip ratio of the right front wheel, and increase the front axle target braking force faster as the slip ratio reduction rate increases. When the larger of the slip ratio of the left rear wheel and the slip ratio of the right rear wheel is less than the rear axle reference slip ratio, the dynamic adjustment module 224 may also monitor the slip ratio reduction rate of the larger of the slip ratio of the left rear wheel and the slip ratio of the right rear wheel, and increase the rear axle target braking force faster as the slip ratio reduction rate increases.

[0040] It can be seen that if the wheel slip ratio increases faster, the target braking force decreases faster accordingly. And if the wheel slip ratio decreases faster, the target braking force increases faster accordingly. In this way, vehicle stability can be ensured even when the wheel slip ratio changes rapidly.

[0041] In another embodiment, referring to frame 242, the dynamic adjustment module 224 determines whether to perform adjustment of the target braking force of the front axle based on the difference between the slip rate of the left front wheel and the slip rate of the right front wheel, and determines whether to perform adjustment of the target braking force of the rear axle based on the difference between the slip rate of the left rear wheel and the slip rate of the right rear wheel.

[0042] For example, when the difference between the slip ratio of the left front wheel and the slip ratio of the right front wheel is greater than the front axle slip ratio difference threshold, one strategy is that the dynamic adjustment module 224 prohibits the adjustment of the front axle target braking force; another strategy is that the dynamic adjustment module 224 causes the front axle target braking force to change slowly, for example, the change rate is less than the predetermined change rate threshold. Alternatively, when the ratio between the difference between the slip ratio of the left front wheel and the slip ratio of the right front wheel and the front axle reference slip ratio is greater than a predetermined ratio, one strategy is that the dynamic adjustment module 224 prohibits the adjustment of the front axle target braking force; another strategy is that the dynamic adjustment module 224 causes the front axle target braking force to change slowly, for example, the change rate is less than the predetermined change rate threshold.

[0043] Similarly, when the difference between the slip ratio of the left rear wheel and the slip ratio of the right rear wheel is greater than the rear axle slip ratio difference threshold, one strategy is that the dynamic adjustment module 224 prohibits the adjustment of the rear axle target braking force; another strategy is that the dynamic adjustment module 224 makes the rear axle target braking force change slowly, for example, the change rate is less than the predetermined change rate threshold. Alternatively, when the ratio between the difference between the slip ratio of the left rear wheel and the slip ratio of the right rear wheel and the rear axle reference slip ratio is greater than the predetermined ratio, one strategy is that the dynamic adjustment module 224 prohibits the adjustment of the rear axle target braking force; another strategy is that the dynamic adjustment module 224 makes the rear axle target braking force change slowly, for example, the change rate is less than the predetermined change rate threshold.

[0044] The reason for the large difference in slip rates between the left and right wheels may be that the adhesion coefficients of the roads on which the wheels on both sides of the vehicle are located are very different, for example, one wheel is located on a very smooth road (e.g., an icy road), while the other wheel is located on a very rough road (e.g., a grassy road). In such a situation, the adjustment of the target braking force can be prohibited first, and after the vehicle has traveled through such a road section, when the difference in slip rates between the left and right wheels is not so large, the target braking force can be adjusted; or the target braking force can be adjusted slowly, and the wheel on one side is allowed to lock.

[0045] It can be understood that the front axle slip rate difference threshold, the rear axle slip rate difference threshold and the predetermined ratio described in the above embodiments are predetermined by actual vehicle testing and / or model calculation, and can be adjusted according to specific application scenarios, user needs (e.g., the needs of vehicle manufacturers) and user preferences (e.g., the driving preferences of end users).

[0046] It can be understood that the multiple embodiments of dynamic adjustment introduced above are not mutually exclusive; on the contrary, they can be combined.

[0047] In addition, for vehicles having both hydraulic braking and electric braking functions, such as electric vehicles or hybrid vehicles, the target braking force can also be divided into a portion achieved by hydraulic braking and a portion achieved by electric braking.

[0048] In block 250, the distribution module 225 distributes the front axle target braking force into the hydraulic braking force implemented by the hydraulic brake unit coupled to the front axle and the electric braking force implemented by the front axle motor coupled to the front axle. Similarly, the distribution module 225 distributes the rear axle target braking force into the hydraulic braking force implemented by the hydraulic brake unit coupled to the rear axle and the electric braking force implemented by the rear axle motor coupled to the rear axle.

[0049] In one embodiment, the electric braking force achieved by the motor can be allocated first, that is, the hydraulic braking force is allocated when the maximum electric braking force that the motor can achieve cannot meet the target braking force. In this way, the electric braking capacity of the motor can be fully utilized.

[0050] The braking control for the front axle is described below with reference to some left front wheel and right front wheel slip rate situations listed in Table 1.

[0051] Table 1

[0052]

[0053] In Table 1, the first column indicates the number of the situation, the second column indicates the front axle reference slip rate, the third column indicates the slip rate of the left front wheel, the fourth column indicates the slip rate of the right front wheel, and the fifth column indicates the adjustment direction of the front axle target braking force.

[0054] In case ①, the slip ratio of the left front wheel and the slip ratio of the right front wheel are both greater than the reference slip ratio of the front axle. In this case, the front axle target braking force is adjusted in the direction of reduction.

[0055] In case ②, one of the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the front axle reference slip rate, while the other is less than the front axle reference slip rate. This is a case where the larger of the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the front axle reference slip rate. In this case, the front axle target braking force is adjusted in the direction of reduction.

[0056] In case ③, the larger of the slip ratio of the left front wheel and the slip ratio of the right front wheel is smaller than the front axle reference slip ratio. In this case, the front axle target braking force is adjusted in the direction of increasing.

[0057] In case ④, the slip rate of the left front wheel and the slip rate of the right front wheel are exactly equal to the reference slip rate of the front axle. In this case, the front axle target braking force remains unchanged.

[0058] In case ⑤, one of the slip rate of the left front wheel and the slip rate of the right front wheel is equal to the front axle reference slip rate, while the other is greater than the front axle reference slip rate. This is a case where the larger of the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the front axle reference slip rate. In this case, the front axle target braking force is adjusted in a decreasing direction.

[0059] In case ⑥, one of the slip rate of the left front wheel and the slip rate of the right front wheel is equal to the front axle reference slip rate, while the other is slightly smaller than the front axle reference slip rate. In this case, the front axle target braking force remains unchanged.

[0060] In situation ⑦, the difference between the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the front axle slip rate difference threshold. This situation may be that the vehicle is in a special road condition, for example, one side has high adhesion (for example, asphalt road) and the other side has low adhesion (for example, icy road). In this situation, one approach is: do not immediately perform the adjustment of the front axle target braking force, but wait for the difference between the slip rate of the left front wheel and the slip rate of the right front wheel to decrease to less than or equal to the front axle slip rate difference threshold, and then perform the adjustment of the front axle target braking force. Another approach is: the front axle target braking force can be slowly increased while allowing the right front wheel to lock.

[0061] It is understood that the values ​​in Table 1 are exemplary and are not intended to limit the scope of protection of the present invention. In addition, the slip rate of the left rear wheel and the right rear wheel and the corresponding braking control can refer to the above description and will not be repeated.

[0062] It is to be understood that all operations in the method described above are merely exemplary, and the present invention is not limited to any operation in the method or the order of these operations, but should cover all other equivalent transformations under the same or similar concept.

[0063] The present invention also provides a machine-readable storage medium storing executable instructions. When the instructions are executed by one or more processors, the brake control method described above is executed.

[0064] It is understood that software can be widely regarded as representing instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, running threads, processes, functions, etc. Software can reside in a computer-readable medium. A computer-readable medium can include, for example, a memory, which can be, for example, a magnetic storage device (e.g., a hard disk, a floppy disk, a magnetic stripe), an optical disk, a smart card, a flash memory device, a random access memory (RAM), a read-only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), a register, or a removable disk. Although the memory is shown as being separated from the processor in the various aspects provided by the present invention, the memory can also be located inside the processor (e.g., a cache or a register).

[0065] The above description is provided to enable any person skilled in the art to implement the various aspects described herein. Various modifications to these aspects are apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein. All structural and functional equivalents of elements of the various aspects described herein that are known or to be known to those skilled in the art will be expressly included herein by reference and are intended to be covered by the claims.

Claims

1. A control unit for vehicle braking, adapted to provide braking control for the vehicle when the main braking system of the vehicle fails, the control unit comprising: A receiving module configured to receive wheel speed information, which includes a left front wheel speed and a right front wheel speed coupled to a front axle of the vehicle, and a left rear wheel speed and a right rear wheel speed coupled to a rear axle of the vehicle; A calculation module configured to calculate the slip rate of each wheel based on the wheel speed of each wheel; a comparison module configured to compare a larger one of the slip ratio of the left front wheel and the slip ratio of the right front wheel with a front axle reference slip ratio, and to compare a larger one of the slip ratio of the left rear wheel and the slip ratio of the right rear wheel with a rear axle reference slip ratio; as well as a dynamic adjustment module configured to dynamically adjust the front axle target braking force and the rear axle target braking force of the vehicle based on the comparison result, The dynamic adjustment includes: When the larger one of the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the reference slip rate of the front axle, reducing the front axle target braking force; When the larger one of the slip rate of the left rear wheel and the slip rate of the right rear wheel is greater than the rear axle reference slip rate, reducing the rear axle target braking force; When the larger of the slip ratio of the left front wheel and the slip ratio of the right front wheel is smaller than the front axle reference slip ratio, increasing the front axle target braking force; and When the larger one of the slip ratio of the left rear wheel and the slip ratio of the right rear wheel is smaller than the rear axle reference slip ratio, the rear axle target braking force is increased.

2. The control unit according to claim 1, wherein: The dynamic adjustment module is also configured to: prohibiting adjustment of the front axle target braking force when a difference between the slip ratio of the left front wheel and the slip ratio of the right front wheel is greater than a front axle slip ratio difference threshold; and When the difference between the slip ratio of the left rear wheel and the slip ratio of the right rear wheel is greater than the rear axle slip ratio difference threshold, adjustment of the rear axle target braking force is prohibited.

3. A control unit according to claim 1 or 2, wherein: The dynamic adjustment module is also configured to: monitoring an increase rate of a larger one of a slip ratio of a left front wheel and a slip ratio of a right front wheel, and causing the front axle target braking force to decrease faster as the increase rate increases; as well as An increasing rate of the larger one of the slip ratio of the left rear wheel and the slip ratio of the right rear wheel is monitored, and the larger the increasing rate is, the faster the rear axle target braking force is reduced.

4. A control unit according to any one of claims 1 to 3, wherein: The dynamic adjustment module is also configured to: monitoring a decreasing rate of a larger one of a slip ratio of a left front wheel and a slip ratio of a right front wheel, and causing the front axle target braking force to increase faster the larger the decreasing rate is; as well as A decreasing rate of the larger one of the slip ratio of the left rear wheel and the slip ratio of the right rear wheel is monitored, and the rear axle target braking force is increased faster the larger the decreasing rate is.

5. A control unit according to any one of claims 1 to 4, wherein: The dynamic adjustment module is also configured to: monitoring a ratio of a difference between a slip ratio of a left front wheel and a slip ratio of a right front wheel to a reference slip ratio of a front axle, and prohibiting adjustment of a target braking force of the front axle when the ratio is greater than a predetermined ratio; as well as A ratio of a difference between the slip ratio of the left rear wheel and the slip ratio of the right rear wheel to a reference slip ratio of the rear axle is monitored, and when the ratio is greater than the predetermined ratio, adjustment of the rear axle target braking force is prohibited.

6. A control unit according to any one of claims 1 to 5, wherein: The front axle reference slip ratio is greater than the rear axle reference slip ratio.

7. The control unit according to any one of claims 1 to 6, further comprising a distribution module configured to: Distributing the front axle target braking force into a hydraulic braking force achieved by a hydraulic brake unit coupled to the front axle and an electric braking force achieved by a motor coupled to the front axle; and The rear axle target braking force is distributed into a hydraulic braking force achieved by a hydraulic brake unit coupled to the rear axle and an electric braking force achieved by an electric motor coupled to the rear axle.

8. A vehicle braking system, comprising: A main brake system for providing four-wheel independently controlled braking; as well as Auxiliary brake system, used to provide split-axle controlled braking when the main brake system fails; Wherein, the auxiliary braking system comprises: Wheel speed sensors for sensing the wheel speeds of the left front wheel and the right front wheel coupled to the front axle of the vehicle, and the wheel speeds of the left rear wheel and the right rear wheel coupled to the rear axle of the vehicle; and The control unit according to any one of claims 1 to 7, configured to: dynamically adjust the front axle target braking force and the rear axle target braking force of the vehicle based on the comparison result; a first hydraulic linear valve configured to perform a valve opening corresponding to the front axle target braking force to adjust the slip ratios of the left and right front wheels; and The second hydraulic linear valve is configured to perform a valve opening corresponding to the rear axle target braking force to adjust the slip ratio of the left rear wheel and the right rear wheel.

9. A vehicle braking control method, comprising: When the main brake system of the vehicle fails, wheel speed information is received, which includes the wheel speed of the left front wheel and the wheel speed of the right front wheel coupled to the front axle of the vehicle, and the wheel speed of the left rear wheel and the wheel speed of the right rear wheel coupled to the rear axle of the vehicle; Calculate the slip rate of each wheel based on the wheel speed of each wheel; comparing a larger one of a slip ratio of a left front wheel and a slip ratio of a right front wheel with a front axle reference slip ratio, and comparing a larger one of a slip ratio of a left rear wheel and a slip ratio of a right rear wheel with a rear axle reference slip ratio; as well as Based on the comparison results, the front axle target braking force and rear axle target braking force of the vehicle are dynamically adjusted. The dynamic adjustment includes: When the larger one of the slip rate of the left front wheel and the slip rate of the right front wheel is greater than the reference slip rate of the front axle, reducing the front axle target braking force; When the larger one of the slip rate of the left rear wheel and the slip rate of the right rear wheel is greater than the rear axle reference slip rate, reducing the rear axle target braking force; When the larger of the slip ratio of the left front wheel and the slip ratio of the right front wheel is smaller than the front axle reference slip ratio, increasing the front axle target braking force; and When the larger of the slip ratio of the left rear wheel and the slip ratio of the right rear wheel is smaller than the rear axle reference slip ratio, the rear axle target braking force is increased. Optionally, the method is performed by a control unit as described in any one of claims 1 to 7 or a system as described in claim 8.

10. A machine-readable storage medium comprising executable instructions which, when executed by one or more processors, cause the method of claim 9 to be performed.

Images