Braking control method and system of distributed braking system

Abstract

The embodiment of the present application provides a brake control method and system for a distributed brake system, which is applied to a vehicle, wherein the brake domain controller is connected to the wheel side controller via a high-speed bus communication, and the wheel side controller is connected to the wheel speed sensor via a signal line communication; when the high-speed bus communication fails, the brake domain controller enters a fault state, and the wheel side controller applies a target clamping force to the vehicle's wheel through an electronic caliper, and controls the electronic caliper according to the wheel speed signal collected by the wheel speed sensor to achieve wheel braking. The safe braking of the vehicle is achieved through the wheel side controller, improving the safety and robustness of the distributed brake system, and the wheels are controlled by the target clamping force to achieve safe braking with the minimum deceleration, ensuring that the vehicle can still achieve safe braking even when the high-speed bus communication fails and cannot be controlled by the brake domain controller, thereby improving safety and system robustness.

Description

Technical Field

[0001] The present application relates to the field of vehicle braking, and in particular to a braking control method and system for a distributed braking system. Background Art

[0002] Distributed braking systems (such as Figure 1 As shown in the figure, it is precisely constructed by the electronic brake pedal, brake domain controller and four wheel side controllers (Wheel Control Unit, WCU). Each WCU is closely connected with the wheel speed sensor (Wheel Speed ​​Sensor, WSS) to achieve accurate monitoring of wheel speed and independently control the electronic caliper of a single wheel.

[0003] Among them, the electronic brake pedal is used to convert the driver's brake control into an electrical signal and transmit it to the brake domain controller, and at the same time convert it into a vehicle high-speed bus signal, which is transmitted to the brake domain controller and four wheel-side controllers in the electric control brake system as a redundant signal channel. The brake domain controller, as the brain, analyzes the electrical signal of the electronic brake pedal, correctly identifies the driver's braking intention, and then performs logical operations on the brake assist function, and outputs the brake control command to the wheel-side controller through the vehicle high-speed bus; the wheel speed sensor, as a sensor unit for wheel dynamic perception, is a necessary input signal for the chassis control function.

[0004] In the distributed braking system, the wheel speed sensor is directly connected to the wheel-side controller, which supplies power to the sensor, collects and processes signals, and sends the four wheel speed sensor signals to the vehicle's high-speed bus. The wheel-side controller receives the wheel-side braking instructions from the brake domain controller, controls the clamping and release of the electronic caliper, and can provide a parking control interface.

[0005] To realize the anti-lock braking system (ABS), the brake domain controller receives the wheel speed sensor on the high-speed bus, verifies the rationality of the four wheel speed sensor signals, and calculates the reference speed of the vehicle and the slip rate of each wheel. The brake domain controller adjusts the single wheel braking force command in real time according to the slip rate of each wheel to avoid wheel locking.

[0006] However, when a failure occurs in the vehicle's high-speed communication bus, how to achieve normal braking of the vehicle is a technical problem that needs to be solved urgently. Summary of the invention

[0007] The purpose of this application is to solve the technical problem in the prior art of how to achieve safe braking of a vehicle when a high-speed communication bus in a distributed braking system fails. Therefore, this application provides a braking control method and system for a distributed braking system. When a high-speed bus fails, safe braking of the vehicle is achieved through a wheel-side controller, thereby improving the safety and robustness of the distributed braking system.

[0008] The embodiment of the present application provides a brake control method of a distributed brake system, which is applied to a vehicle. The distributed brake system includes: a brake domain controller, a wheel side controller, a wheel speed sensor and an electronic caliper. The brake domain controller is connected to the wheel side controller via a high-speed bus communication, and the wheel side controller is connected to the wheel speed sensor via a signal line communication.

[0009] When the high-speed bus communication fails, the brake domain controller enters a fault state. The wheel-side controller applies the target clamping force to the vehicle's wheels through the electronic caliper, and controls the electronic caliper according to the wheel speed signal collected by the wheel speed sensor to achieve wheel braking. The target clamping force is used to control the wheel to brake at the lowest deceleration. When the vehicle is moving, the wheel speed sensor collects the wheel speed signal in real time.

[0010] By adopting the above technical solution, when the high-speed bus in the distributed braking system fails, the vehicle can be safely braked through the wheel-side controller, thereby improving the safety and robustness of the distributed braking system. In addition, the wheels can be controlled with the minimum deceleration through the target clamping force to achieve safe braking, thereby ensuring that the vehicle can still achieve safe braking even when the high-speed bus communication fails and cannot be controlled by the brake domain controller, thereby improving safety and system robustness.

[0011] In some embodiments, after applying the target clamping force to the wheel through the electronic caliper, the wheel controller controls the wheel to brake at the minimum deceleration according to the wheel speed signal.

[0012] By adopting the above technical solution, when a high-speed bus in the distributed braking system fails, the wheel-side controller applies the target clamping force to the wheel and then controls the vehicle to brake at the minimum deceleration through the wheel speed signal collected in real time, so as to prevent the vehicle from suddenly decelerating drastically or the wheels from locking, causing the vehicle to lose stability, thereby ensuring safe braking of the vehicle and improving safety.

[0013] In some embodiments, the wheel controller calculates the wheel deceleration and the wheel deceleration change rate according to the wheel speed signal;

[0014] Determine whether to release the target clamping force based on the wheel deceleration and the deceleration threshold, and the deceleration threshold is used to determine whether the wheel is locked;

[0015] and\or,

[0016] Whether to release the target clamping force is determined based on the wheel deceleration change rate and the change rate threshold. The change rate threshold is used to determine whether the wheel is prone to locking.

[0017] In some embodiments, if the wheel deceleration is greater than the deceleration threshold, the electronic caliper is controlled to release the target clamping force;

[0018] If the wheel deceleration is less than or equal to the wheel deceleration threshold, the electronic caliper is controlled to apply the target clamping force;

[0019] and\or,

[0020] If the wheel deceleration change rate is greater than the change rate threshold, the electronic caliper is controlled to release the target clamping force;

[0021] If the wheel deceleration change rate is less than or equal to the change rate threshold, the electronic caliper is controlled to apply the target clamping force.

[0022] By adopting the above technical solution, the wheel-side controller prevents wheel locking or sudden drastic deceleration during the vehicle's braking process based on the wheel deceleration threshold and the wheel deceleration change rate threshold, thereby ensuring the safety of vehicle braking and smooth braking of the vehicle.

[0023] In some embodiments, the wheel controller calculates the wheel deceleration and the wheel deceleration change rate according to the wheel speed signal, including:

[0024] According to the wheel speed signal of the first collection cycle collected by the wheel speed sensor and the average wheel speed of N-1 collection cycles before the first collection cycle, the average wheel speed of the first collection cycle is obtained, where N is a positive integer;

[0025] The wheel deceleration and the wheel deceleration change rate are obtained according to the average wheel speed of the first collection period and the second collection period, and the second collection period is the period before the first collection period.

[0026] By adopting the above technical solution, during the braking process of the vehicle, the wheel speed sensor collects the wheel speed signal of the wheel in real time, and calculates the wheel deceleration and the wheel deceleration change rate, so as to monitor the braking effect of the vehicle in real time and ensure the safe braking of the vehicle.

[0027] In some embodiments, when the braking system of the vehicle is calibrated, the target clamping force under different vehicle operating conditions is determined based on the minimum deceleration.

[0028] In some embodiments, the vehicle includes front wheels and rear wheels, and the target clamping force includes: a front wheel clamping force and a rear wheel clamping force;

[0029] Determine the front wheel braking force applied to the front wheel and the rear wheel braking force applied to the rear wheel by the wheel-side controller according to the front wheel normal reaction force applied to the front wheel and the rear wheel normal reaction force applied to the rear wheel when the vehicle brakes at the minimum deceleration;

[0030] According to the front wheel braking force and the rear wheel braking force, the front wheel clamping force of the front wheel and the rear wheel clamping force of the rear wheel are obtained.

[0031] In some embodiments, the front wheels include: a left front wheel and a right front wheel, and the rear wheels include: a left rear wheel and a right rear wheel;

[0032] The left and right front wheels are controlled by front wheel clamping force;

[0033] The left and right rear wheels are controlled by rear wheel clamping force.

[0034] By adopting the above technical solution, the braking control of the four wheels of the vehicle is performed simultaneously, which can ensure the safety of vehicle braking.

[0035] In some embodiments, the brake domain controller sends a warning message to the vehicle when entering a fault state.

[0036] By adopting the above technical solution, when a high-speed bus fails, a warning message can be sent to the vehicle to remind the vehicle driver to take safe braking measures or to inspect the vehicle's braking system, thereby ensuring safe braking and safety of the vehicle.

[0037] An embodiment of the present application also provides a braking control system of a distributed braking system, including the braking control method of the distributed braking system described above.

[0038] The present application provides a braking control method and system for a distributed braking system. When a high-speed bus in the distributed braking system fails, safe braking of the vehicle is achieved through a wheel-side controller, thereby improving the safety and robustness of the distributed braking system. Furthermore, the wheel is controlled with a target clamping force to achieve safe braking at a minimum deceleration, thereby ensuring that the vehicle can still achieve safe braking even when the high-speed bus communication fails and the vehicle cannot be controlled by the braking domain controller, thereby improving safety and system robustness. This method ensures to the greatest extent that the vehicle can still perform parking braking when a distributed braking system fails, thereby effectively shortening the impact time of the failure and ensuring the safe operation of the vehicle. The method has strong versatility and expansibility, thereby providing strong support for maintenance and management and reducing maintenance costs. Furthermore, the wheel-side controller does not need to add more redundant communication buses, thereby saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of the structure of a distributed braking system according to an embodiment of the present application;

[0040] Figure 2 A schematic diagram of a high-speed bus failure in a distributed braking system according to an embodiment of the present application;

[0041] Figure 3A schematic diagram of a wheel speed curve according to an embodiment of the present application;

[0042] Figure 4 A schematic diagram of a wheel deceleration curve in an embodiment of the present application;

[0043] Figure 5 A schematic diagram of a curve of a wheel deceleration change rate in an embodiment of the present application;

[0044] Description of reference numerals:

[0045] WSS, wheel speed sensor;

[0046] FL_WCU, left front wheel controller; FR_WCU, right front wheel controller; RL_WCU, left rear wheel controller; RR_WCU, right rear wheel controller;

[0047] Vt, wheel speed; a, acceleration; , wheel deceleration change rate; t, time;

[0048] , minimum deceleration; , deceleration threshold; , change rate threshold;

[0049] S1, release the target clamping force at S1;

[0050] S2. Apply target clamping force at S2. DETAILED DESCRIPTION

[0051] The following specific embodiments illustrate the implementation of the present application, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Although the description of the present application will be introduced in conjunction with some embodiments, this does not mean that the features of this application are limited to the implementation. On the contrary, the purpose of introducing the application in conjunction with the implementation is to cover other options or modifications that may be extended based on the claims of the present application. In order to provide a deep understanding of the present application, the following description will include many specific details. The present application can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0052] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0053] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0054] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0055] In the description of the present application, it should be understood that in the present application, "electrical connection" can be understood as physical contact and electrical conduction between components; it can also be understood as a form in which different components in the circuit structure are connected through physical lines such as printed circuit board (PCB) copper foil or wires that can transmit electrical signals. "Coupled by..." can be understood as electrical conduction through air by indirect coupling. Indirect coupling can be understood as contactless coupling, in which, it can be understood by those skilled in the art that the coupling phenomenon refers to the phenomenon that there is close cooperation and mutual influence between the input and output of two or more circuit elements or electrical networks, and energy is transmitted from one side to the other through interaction. In order to make the purpose, technical solution and advantages of the present application clearer, the implementation method of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0056] In a distributed braking system, such as Figure 1 As shown, electronic calipers and corresponding WCUs are respectively provided for the four wheels of the vehicle, specifically including a left front wheel side controller (FL_WCU), a right front wheel side controller (FR_WCU), a left rear wheel side controller (RL_WCU) ​​and a right rear wheel side controller (RR_WCU), wherein a wheel speed sensor (WSS) is respectively provided on the four wheels, the WSS is communicatively connected with the corresponding WCU through a signal line, the FL_WCU, FR_WCU, RL_WCU and RR_WCU are communicatively connected with the brake domain controller through a high-speed bus, the electronic brake pedal is communicatively connected with the brake domain controller through a signal line, and is communicatively connected with the brake domain controller and all WCUs through a high-speed bus.

[0057] In the prior art, when a brake domain controller, a wheel side controller, or a wheel speed sensor fails, there are corresponding brake control methods to implement vehicle brake control. However, when a high-speed bus fails, there is no corresponding method to implement vehicle brake control.

[0058] When the high-speed bus in the distributed braking system fails, although the braking domain controller and the four wheel-side controllers can still operate normally, the braking domain controller cannot pass the braking instructions to the four wheel-side controllers, and the wheel-side controllers cannot pass the wheel speed signals to the braking domain controller. Therefore, the vehicle's braking control cannot be completed normally, and there is a safety issue.

[0059] Based on the above technical problems, an embodiment of the present application provides a braking control method and system for a distributed braking system to improve the safety and robustness of the distributed braking system.

[0060] The present application embodiment provides a brake control method and system of a distributed brake system, which is applied to a vehicle, such as Figure 1 As shown, the distributed braking system includes: a brake domain controller, a wheel side controller (WCU), a wheel speed sensor (WSS) and an electronic caliper.

[0061] Among them, the brake domain controller and the wheel side controller are connected through high-speed bus communication, and the wheel side controller and the wheel speed sensor are connected through signal line communication.

[0062] It is known that communication connection is used to describe data transmission and information exchange between devices, systems or components in some way (such as wired or wireless). Exemplary, it can be a high-speed bus, signal line, etc.

[0063] like Figure 2 As shown, when the high-speed bus communication fails, the brake domain controller enters a fault state, and the wheel-side controller applies a target clamping force to the vehicle's wheels through the electronic caliper, and controls the electronic caliper according to the wheel speed signal collected by the wheel speed sensor to achieve wheel braking.

[0064] Specifically, when a high-speed bus fails in the distributed braking system, safe braking of the vehicle is achieved through the wheel-side controller, thereby improving the safety and robustness of the distributed braking system. In addition, the wheels are controlled with the target clamping force to achieve safe braking with the minimum deceleration, ensuring that the vehicle can still achieve safe braking even when the high-speed bus communication fails and the vehicle cannot be controlled by the braking domain controller, thereby improving safety and system robustness.

[0065] Among them, the target clamping force is used to control the wheel to brake at the minimum deceleration, and the wheel speed sensor collects the wheel speed signal in real time when the vehicle is moving.

[0066] It is known that in order to ensure public safety, many countries and regions have stipulated the minimum deceleration standard for vehicles when the brakes fail, so as to ensure that the vehicle can still be safely parked in the event of a brake system failure. For example, the "Technical Conditions for Motor Vehicle Operation Safety" GB 7258 stipulates that the minimum deceleration of a vehicle when the brakes fail is 2.44 meters per second squared (m / s). ), therefore, in the embodiment of the present application, there is no restriction on the setting of the minimum deceleration, which is mainly set according to relevant regulations and the conditions that can make the vehicle stop safely in the event of brake failure. For example, the minimum deceleration can be set to be greater than or equal to 2.44m / .

[0067] Specifically, when a high-speed bus communication fails, the brake domain controller enters a fault state, including: after power-on, the brake domain controller will enter the initialization self-test state by default; after completing the self-test, it enters the normal working state; when the wheel speed signals of the four wheel-side controllers cannot be received or a high-speed bus off state (BUS OFF) fault occurs, the brake domain controller enters a fault state and needs to send an electronic control brake system warning message to the vehicle through the human-computer interaction interface and light up the warning light.

[0068] The embodiment of the present application can send a warning message to the vehicle when a high-speed bus fails to remind the vehicle driver to take safe braking measures or to inspect the vehicle's braking system, thereby ensuring safe braking and safety of the vehicle.

[0069] Furthermore, after applying the target clamping force to the wheel through the electronic caliper, the wheel controller controls the wheel to brake at the minimum deceleration according to the wheel speed signal.

[0070] In actual situations, after the wheel-side controller is powered on, it enters the normal working state after the initialization self-check state; when it detects that there is no high-speed bus communication or the high-speed bus BUS OFF, it enters the high-speed bus network fault state. At this time, the wheel-side controller controls the clamping and release of the electronic caliper.

[0071] Furthermore, in the embodiment of the present application, when the braking system of the vehicle is calibrated, the target clamping force under different operating conditions of the vehicle is determined based on the minimum deceleration.

[0072] How to determine the target clamping force under different vehicle working conditions according to the minimum deceleration will be described below in conjunction with specific embodiments.

[0073] In the embodiment of the present application, the vehicle includes front wheels and rear wheels; the target clamping force includes: front wheel clamping force and rear wheel clamping force.

[0074] In some optional embodiments, the front wheel braking force applied to the front wheel and the rear wheel braking force applied to the rear wheel by the wheel-side controller are determined based on the front wheel normal reaction force received by the front wheel and the rear wheel normal reaction force received by the rear wheel when the vehicle is braked at the minimum deceleration; the front wheel clamping force of the front wheel and the rear wheel clamping force of the rear wheel are obtained based on the front wheel braking force and the rear wheel braking force.

[0075] Among them, the front wheels include: a left front wheel and a right front wheel, and the rear wheels include: a left rear wheel and a right rear wheel; the left front wheel and the right front wheel are controlled by the front wheel clamping force; the left rear wheel and the right rear wheel are controlled by the rear wheel clamping force.

[0076] In the embodiment of the present application, braking control is performed on the four wheels of the vehicle simultaneously, thereby ensuring the safety of vehicle braking.

[0077] First, under the same road adhesion coefficient, in order to ensure that the front and rear wheels of the vehicle can generate maximum braking force, it is necessary to consider the ideal braking force distribution between the front and rear wheels. ) The distribution of front wheel braking force and rear wheel braking force during braking is checked.

[0078] Since the torque generated by the vehicle's center of mass on the front and rear axles is different under different decelerations, the normal reaction force on the front wheel is first calculated using formula (1), and the normal reaction force on the rear wheel is calculated using formula (2).

[0079]

[0080] Wherein, represents the normal reaction force of the front wheel; represents the normal reaction force of the rear wheel; L represents the wheelbase of the vehicle; a represents the distance from the center of gravity of the vehicle to the front axle; b represents the distance from the center of gravity of the vehicle to the rear axle; m represents the mass of the vehicle; mg represents the gravity of the vehicle; represents the height of the center of gravity of the vehicle; g represents the acceleration due to gravity (g=9.8m / ).

[0081] After the front wheel normal reaction force and the rear wheel normal reaction force are calculated, the front wheel braking force and the rear wheel braking force are obtained according to the magnitude relationship between the front wheel normal reaction force and the rear wheel normal reaction force using formula (3).

[0082]

[0083] in, Indicates the front wheel braking force; Indicates the rear wheel braking force.

[0084] Then, the front wheel clamping force and the rear wheel clamping force are obtained according to the front wheel braking force and the rear wheel brake wheel, and the front wheel clamping force is obtained by formula (4) and the rear wheel clamping force is obtained by formula (5) considering the equal distribution of the braking force on the left and right sides.

[0085] in, Indicates the front wheel clamping force of the left front wheel; Indicates the front wheel clamping force of the right front wheel; ; Indicates the rear wheel clamping force of the left rear wheel; Indicates the rear wheel clamping force of the right rear wheel; ; Indicates the dynamic rolling radius of the front wheel; Indicates the dynamic rolling radius of the rear wheel; Indicates the effective braking radius of the front electronic caliper; Indicates the effective braking radius of the rear electronic caliper; Indicates the front electronic caliper effectiveness factor; Indicates the rear electronic caliper effectiveness factor.

[0086]

[0087]

[0088] Finally, according to the vehicle parameters, the minimum deceleration of the vehicle can be obtained ( ) The clamping force corresponding to the wheel-side controllers of the front and rear four wheels under different working conditions, namely the front wheel clamping force and the rear wheel clamping force.

[0089] In the embodiment of the present application, there is no restriction on the method of distributing the braking force on the left and right sides of the front wheels and the rear wheels, and it can be set according to actual conditions to achieve safe braking of the vehicle by distributing the braking force on the left and right sides. Exemplarily, the braking force on the left and right sides is set to be evenly distributed.

[0090] In an embodiment of the present application, in order to ensure smooth and safe braking of the vehicle, after the wheel-side controller applies the target clamping force to the wheel through the electronic caliper, the wheel speed sensor continues to collect the wheel speed signal in real time and upload it to the wheel speed sensor. The wheel speed sensor controls the wheel to brake at the lowest deceleration according to the wheel speed signal.

[0091] In some optional embodiments, the wheel controller calculates the wheel deceleration and the wheel deceleration change rate based on the wheel speed signal, including: obtaining the average wheel speed of the first collection period based on the wheel speed signal of the first collection period collected by the wheel speed sensor and the average wheel speed of N-1 collection periods before the first collection period, where N is a positive integer; obtaining the wheel deceleration and the wheel deceleration change rate based on the average wheel speed of the first collection period and the second collection period, where the second collection period is the period before the first collection period.

[0092] Optionally, the wheel-side controller calculates the wheel deceleration and the wheel deceleration change rate based on the wheel speed signal, including: obtaining a first average speed based on the wheel speed signal of N collection cycles collected by the wheel speed sensor in a first round, where N is an integer; obtaining a second average speed based on the wheel speed signal of N collection cycles collected by the wheel speed sensor in a second round, the second round and the second round indicate that the wheel speed sensor continuously collects the wheel speed signal with a collection cycle when the vehicle is moving; obtaining the wheel deceleration and the wheel deceleration change rate based on the speed difference between the second average speed and the first average speed, and the collection cycle.

[0093] Specifically, during the braking process of the vehicle, the wheel speed sensor collects the wheel speed signal of the wheel in real time, and calculates the wheel deceleration and the wheel deceleration change rate, which can monitor the braking effect of the vehicle in real time and ensure the safe braking of the vehicle.

[0094] In some optional embodiments, the wheel-side controller calculates the wheel deceleration and the wheel deceleration change rate based on the wheel speed signal; determines whether to release the target clamping force based on the wheel deceleration and the deceleration threshold; and\or, determines whether to release the target clamping force based on the wheel deceleration change rate and the change rate threshold.

[0095] The deceleration threshold is used to determine whether the wheel is locked, and the change rate threshold is used to determine the tendency of the wheel to lock.

[0096] Specifically, the wheel controller prevents wheel locking or sudden drastic deceleration during the braking process of the vehicle based on the wheel deceleration threshold and the wheel deceleration change rate threshold, thereby ensuring the safety of vehicle braking and smooth braking of the vehicle.

[0097] Furthermore, if the wheel deceleration is greater than the deceleration threshold, the electronic caliper is controlled to release the target clamping force; if the wheel deceleration is less than or equal to the wheel deceleration threshold, the electronic caliper is controlled to apply the target clamping force; and\or, if the wheel deceleration change rate is greater than the change rate threshold, the electronic caliper is controlled to release the target clamping force; if the wheel deceleration change rate is less than or equal to the change rate threshold, the electronic caliper is controlled to apply the target clamping force.

[0098] The following describes a specific embodiment in which the wheel speed sensor controls the wheel to brake at the minimum deceleration according to the wheel speed signal.

[0099] Due to the minimum deceleration of the vehicle ( ) has been determined, therefore, the target value of the wheel deceleration of each wheel is set to The wheel controller periodically collects the wheel speed sensor signal of a single wheel, analyzes the wheel speed signal, and calculates the wheel deceleration and wheel deceleration change rate for the slip rate control of a single wheel.

[0100] Specifically, Figure 3As shown in the figure, the horizontal axis is time and the vertical axis is wheel speed. The dotted straight line represents the target wheel speed when braking at the minimum deceleration, and the solid curve represents the wheel speed collected by the wheel speed sensor in real time. The wheel speed sensor signal needs to be collected continuously for N collection cycles (N is recommended to be an integer of 3 to 5). The wheel speed signals of N collection cycles are averaged, and then the average speed of the previous collection cycle is subtracted and divided by the collection cycle ( ) then the wheel deceleration is obtained.

[0101] Exemplarily, when N is selected as 3, the first acquisition cycle acquires the wheel speed signal of the Mth cycle, and also needs to acquire the wheel speed signals of the M-1th cycle and the M-2th cycle, where M represents an arbitrary integer; the second acquisition cycle acquires the wheel speed signal of the M-1th cycle, and also needs to acquire the wheel speed signals of the M-2th cycle and the M-3th cycle, and the wheel deceleration and the wheel deceleration change rate are obtained by formula (6), formula (7), formula (8) and formula (9).

[0102] Average wheel speed in cycle M-1:

[0103] Va(M-1) =(Va(M-3)+Va(M-2)+Vt(M-1)) / 3; (6)

[0104] Average wheel speed in cycle M:

[0105] Va(M) =(Va(M-2)+Va(M-1)+Vt(M)) / 3; (7)

[0106] The wheel deceleration in the Mth cycle:

[0107] a(M)=(Va(M) - Va(M-1)) / ; (8)

[0108] The rate of change of wheel deceleration in the Mth cycle:

[0109] =|(a(M)-a(M-1))| / . (9)

[0110] Among them, Vt (M) represents the wheel speed signal of the Mth cycle; Vt (M-1) represents the wheel speed signal of the M-1th cycle; Va (M-3) represents the average wheel speed of the M-3th cycle; Va (M-2) represents the average wheel speed of the M-2th cycle; Va (M-1) represents the average wheel speed corresponding to the M-1th cycle; Va (M) represents the average wheel speed corresponding to the Mth cycle; a (M) represents the wheel deceleration corresponding to the Mth cycle; a (M-1) represents the wheel deceleration corresponding to the M-1th cycle; Indicates the rate of change of wheel deceleration corresponding to the Mth cycle.

[0111] Furthermore, when the wheel deceleration occurs, the wheel deceleration range should be controlled not to exceed the deceleration threshold ( ), if the deceleration threshold is exceeded, wheel locking may occur and the wheels will lose lateral force, causing the vehicle to lose stability. The parameter setting needs to be completed through vehicle calibration, and 15% of the wheel slip rate is usually used to determine it. When the wheel deceleration drops back to After that, the wheel-side controller reapplies the target clamping force so that the wheel can keep turning, thus achieving stable braking.

[0112] For example, Figure 4 As shown, the vertical axis is acceleration, the dashed line represents the target deceleration after the vehicle starts to decelerate, and the solid line represents the actual deceleration of the vehicle during braking. At S1, the wheel deceleration range exceeds the deceleration threshold ( ), in order to prevent the vehicle from locking or other situations, the wheel side controller releases the target clamping force at S1 to allow the wheels to resume normal rotation; when the vehicle's wheel deceleration returns to After that, the wheel-side controller reapplies the target controller.

[0113] Furthermore, the wheel deceleration change rate is used to determine the tendency of wheel locking in advance and control the target clamping force of the wheel edge in advance to avoid causing the vehicle to lose stability. ) requires the vehicle to be calibrated to complete parameter setting. When the wheel deceleration change rate exceeds the change rate threshold ( ), the wheel side controller releases the target clamping force. When the wheel deceleration rate drops back to After that, the wheel side controller reapplies the target clamping force.

[0114] For example, Figure 5 The vertical axis is the rate of change of acceleration. At S1, the rate of change of the wheel deceleration of the vehicle exceeds the rate of change threshold, that is, the speed of the vehicle decreases sharply. To avoid the situation where the speed of the vehicle decreases sharply, the wheel side controller releases the target clamping force at S1, and the rate of change of the wheel deceleration drops back to the target value at S2. After that, the wheel side controller reapplies the target clamping force.

[0115] Finally, the vehicle is braked and brought to a stop by controlling the wheel deceleration and the slip rate of the wheel deceleration change rate. When the vehicle stops, in order to prevent slipping, the vehicle is braked for a period of time ( ), and the target clamping force is still maintained within 10 minutes. The maintenance time can be adjusted according to the vehicle voltage conditions. Exemplarily, the maintenance time is greater than 10 minutes.

[0116] In the embodiment of the present application, the four wheel-side controllers are all controlled by the above-mentioned braking control method, and at the same time provide braking clamping force for the longitudinal deceleration control of the vehicle. The vehicle can be parked slowly and ensure that the vehicle does not lose control.

[0117] It can be seen that the wheel-side controller in the embodiment of the present application does not need to add more redundant communication buses, thus saving costs.

[0118] An embodiment of the present application also provides a braking control system of a distributed braking system, including the braking control method of the distributed braking system described above.

[0119] The present application provides a braking control method and system for a distributed braking system. When a high-speed bus in the distributed braking system fails, safe braking of the vehicle is achieved through a wheel-side controller, thereby improving the safety and robustness of the distributed braking system. Furthermore, the wheel is controlled with a target clamping force to achieve safe braking at a minimum deceleration, thereby ensuring that the vehicle can still achieve safe braking even when the high-speed bus communication fails and the vehicle cannot be controlled by the braking domain controller, thereby improving safety and system robustness. This method ensures to the greatest extent that the vehicle can still perform parking braking when a distributed braking system fails, thereby effectively shortening the impact time of the failure and ensuring the safe operation of the vehicle. The method has strong versatility and expansibility, thereby providing strong support for maintenance and management and reducing maintenance costs. Furthermore, the wheel-side controller does not need to add more redundant communication buses, thereby saving costs.

[0120] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and modifications of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and modifications.

Claims

1. A braking control method of a distributed braking system, applied to a vehicle, wherein the distributed braking system comprises: The brake domain controller, wheel side controller, wheel speed sensor and electronic caliper are characterized in that: The brake domain controller is connected to the wheel side controller via a high-speed bus communication, and the wheel side controller is connected to the wheel speed sensor via a signal line communication; When the high-speed bus communication fails, the brake domain controller enters a fault state, the wheel-side controller applies a target clamping force to the wheel of the vehicle through the electronic caliper, and controls the electronic caliper according to the wheel speed signal collected by the wheel speed sensor to achieve wheel braking, the target clamping force is used to control the wheel to brake at the minimum deceleration, and the wheel speed sensor collects the wheel speed signal in real time when the vehicle is moving; After the wheel controller applies the target clamping force to the wheel through the electronic caliper, the wheel controller controls the wheel to brake at the minimum deceleration according to the wheel speed signal; The wheel controller calculates the wheel deceleration and the wheel deceleration change rate according to the wheel speed signal; determining whether to release the target clamping force according to the wheel deceleration and a deceleration threshold, wherein the deceleration threshold is used to determine whether the wheel is locked; and\or, determining whether to release the target clamping force according to the wheel deceleration change rate and a change rate threshold, wherein the change rate threshold is used to determine whether the wheel has a tendency to lock; If the wheel deceleration is greater than the deceleration threshold, controlling the electronic caliper to release the target clamping force; If the wheel deceleration is less than or equal to the wheel deceleration threshold, controlling the electronic caliper to apply the target clamping force; and\or, If the wheel deceleration change rate is greater than the change rate threshold, controlling the electronic caliper to release the target clamping force; If the wheel deceleration change rate is less than or equal to the change rate threshold, controlling the electronic caliper to apply the target clamping force; The deceleration threshold is set by vehicle calibration; The deceleration threshold is set to 15% of the wheel slip rate.

2. The brake control method of the distributed brake system according to claim 1, characterized in that: The wheel controller calculates the wheel deceleration and the wheel deceleration change rate according to the wheel speed signal, including: The average wheel speed of the first collection period is obtained according to the wheel speed signal of the first collection period collected by the wheel speed sensor and the average wheel speed of N-1 collection periods before the first collection period, where N is a positive integer; The wheel deceleration and the wheel deceleration change rate are obtained according to the average wheel speeds in the first collection period and the second collection period, wherein the second collection period is a period before the first collection period.

3. The brake control method of the distributed brake system according to claim 1, characterized in that: When the braking system of the vehicle is calibrated, the target clamping force under different working conditions of the vehicle is determined according to the minimum deceleration.

4. The brake control method of the distributed brake system according to claim 3, characterized in that: The vehicle comprises front wheels and rear wheels, and the target clamping force comprises: front wheel clamping force and rear wheel clamping force; Determining the front wheel braking force and the rear wheel braking force applied by the wheel-side controller to the front wheel and the rear wheel braking force to the rear wheel according to the front wheel normal reaction force received by the front wheel and the rear wheel normal reaction force received by the rear wheel when the vehicle is braked at the minimum deceleration; According to the front wheel braking force and the rear wheel braking force, a front wheel clamping force of the front wheel and a rear wheel clamping force of the rear wheel are obtained.

5. The brake control method of the distributed brake system according to claim 4, characterized in that: The front wheels include a left front wheel and a right front wheel, and the rear wheels include a left rear wheel and a right rear wheel; The left front wheel and the right front wheel are controlled by the front wheel clamping force; The left rear wheel and the right rear wheel are controlled by the rear wheel clamping force.

6. The brake control method of the distributed brake system according to claim 1, characterized in that: The brake domain controller sends a warning message to the vehicle when entering a fault state.

7. A brake control system of a distributed brake system, characterized in that: A braking control method for a distributed braking system comprising any one of claims 1 to 6.

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