Electromechanical brake system, control method and wheel end electromechanical brake device

Abstract

The application provides an electromechanical brake system, a control method and a wheel end electromechanical brake device, and relates to the technical field of vehicle brake control. The system comprises a first brake controller, a second brake controller, a first communication link, a second communication link, a brake pedal switch and four wheel end electromechanical brake devices; a wheel end controller receives two clamping force instructions respectively, monitors the failure of the clamping force instructions and monitors the state of the two communication links, and determines the available state of the first control branch and the second control branch according to the above. The brake pedal switch is directly connected to each wheel end controller through an independent hard-wire channel; when both control branches are unavailable, each wheel end controller controls the corresponding brake actuator according to the pedal state signal. When the brake pedal is depressed, the target clamping force of the front wheel is a preset non-zero clamping force, and the target clamping force of the rear wheel is zero. The application can realize independent pedal state acquisition and local wheel end brake control when both conventional brake control branches are unavailable.

Description

Technical Field

[0001] This application relates to the field of vehicle braking control technology, and in particular to an electromechanical braking system, control method and wheel-end electromechanical braking device. Background Technology

[0002] With the increasing electrification and intelligence of vehicles, electromechanical braking systems (EMB) are gradually being applied to brake-by-wire systems. EMB systems typically transmit braking requests from the driver or the vehicle control system via electrical signals, and wheel-end controllers located at each wheel control the brake actuators to generate the corresponding clamping force.

[0003] To improve the braking availability of electromechanical braking systems in the event of controller failure or communication failure, existing technologies typically construct redundant braking architectures by setting up multiple brake controllers, configuring redundant communication links, setting up brake signal transmission paths independent of conventional communication links, or having wheel-end controllers implement local braking control in fault conditions.

[0004] In a redundant braking architecture comprising multiple brake controllers and multiple communication links, the braking commands output by different brake controllers and the communication links used to transmit these commands may malfunction. Therefore, each wheel needs to determine whether each control branch can still serve as a valid source of braking control based on the braking command status and communication status from different control sources. When multiple conventional control branches are unavailable, it is also necessary to obtain the driver's braking operation status without relying on these conventional control branches, and based on this, determine whether to implement wheel-end braking control and the corresponding braking force output.

[0005] If braking is triggered directly based on the fault state after an anomaly occurs in the conventional control circuit, unexpected braking force may be generated when the driver does not require braking. If the driver's braking operation status is still transmitted via the malfunctioning brake controller, vehicle gateway, or communication link, the reliable transmission of braking requests to the wheels under fault conditions may be affected. Therefore, there is still room for improvement in how to determine the availability of multiple brake control circuits and, when multiple brake control circuits are unavailable, achieve pedal status acquisition and corresponding wheel-end braking control independent of these control circuits. Summary of the Invention

[0006] This application provides an electromechanical braking system, control method, and wheel-end electromechanical braking device to solve the problem that in an electromechanical braking system with multiple braking control branches, it is difficult to transmit the driver's brake pedal state to the wheel end and implement corresponding braking control without relying on the braking control branches when all of the multiple braking control branches are unavailable.

[0007] To address the aforementioned technical problems, this application provides an electromechanical braking system in a first aspect, comprising a first brake controller, a second brake controller, a first communication link, a second communication link, a brake pedal switch, and four wheel-end electromechanical braking devices; each wheel-end electromechanical braking device includes a wheel-end controller and a brake actuator controlled by the wheel-end controller; the first brake controller is communicatively connected to each wheel-end controller via the first communication link to send a first clamping force command to each wheel-end controller, forming a first control branch; the second brake controller is communicatively connected to each wheel-end controller via the second communication link to send a second clamping force command to each wheel-end controller, forming a second control branch; the brake pedal switch is directly connected to each wheel-end controller via an independent hard-wired channel to output a pedal status signal to each wheel-end controller; Each wheel-end controller is configured to at least: receive a first clamping force command via a first communication link and a second clamping force command via a second communication link; perform failure monitoring on the first clamping force command and the second clamping force command, and monitor the status of the first communication link and the second communication link; determine the availability status of the first control branch and the second control branch based on the failure monitoring results and the monitoring results; and control the corresponding brake actuator based on the pedal status signal when both the first control branch and the second control branch are unavailable.

[0008] Furthermore, in one alternative solution, when the first clamping force command fails or the first communication link is abnormal, the first control branch is determined to be unavailable; when the second clamping force command fails or the second communication link is abnormal, the second control branch is determined to be unavailable.

[0009] Furthermore, in another alternative scheme, when the first clamping force command fails and the first communication link is abnormal, the first control branch is determined to be unavailable; when the second clamping force command fails and the second communication link is abnormal, the second control branch is determined to be unavailable.

[0010] Furthermore, each of the wheel end controllers is also configured to: detect the update status of the first clamping force command and the second clamping force command according to a preset detection cycle, and determine that the first clamping force command is invalid when the first clamping force command has not been updated for a consecutive preset number of detection cycles, and determine that the second clamping force command is invalid when the second clamping force command has not been updated for a consecutive preset number of detection cycles; monitor the communication status of the first communication link and the second communication link, and determine that the first communication link is abnormal when a communication timeout occurs or the first communication link enters a bus shutdown state, and determine that the second communication link is abnormal when a communication timeout occurs or the second communication link enters a bus shutdown state.

[0011] Furthermore, each wheel-end controller is configured to: after determining that both the first control branch and the second control branch are unavailable, determine whether the wheel-end controller has completed initialization; if the wheel-end controller has completed initialization, allow control of the corresponding brake actuator based on the pedal status signal; if the wheel-end controller has not completed initialization, prohibit control of the corresponding brake actuator based on the pedal status signal.

[0012] Furthermore, the independent hardwired channel does not pass through the first brake controller, the second brake controller, and the vehicle gateway node, and the independent hardwired channel is independent of the first communication link and the second communication link in terms of physical wiring and electrical circuit.

[0013] Furthermore, the four wheel-end electromechanical braking devices are respectively installed on the left front wheel, right front wheel, left rear wheel, and right rear wheel of the vehicle; when both the first control branch and the second control branch are unavailable: when the pedal status signal indicates that the brake pedal is not depressed, each wheel-end controller sets the corresponding target clamping force to zero; when the pedal status signal indicates that the brake pedal is depressed, the wheel-end controllers installed on the left front wheel and the right front wheel set the corresponding target clamping force to a preset non-zero clamping force, and the wheel-end controllers installed on the left rear wheel and the right rear wheel set the corresponding target clamping force to zero.

[0014] Furthermore, the wheel end controllers located on the left front wheel and the right front wheel set the corresponding target clamping force to the same preset fixed clamping force when the pedal status signal indicates that the brake pedal is depressed, and maintain the preset fixed clamping force while the pedal status signal continues to indicate that the brake pedal is depressed.

[0015] Furthermore, the preset clamping force corresponding to the electromechanical braking devices at the wheel ends of the left front wheel and the right front wheel is 15kN.

[0016] This application provides a second aspect of an electromechanical braking system control method, applied to the electromechanical braking system described in any of the above technical solutions, comprising: each wheel-end controller determining the availability status of the first control branch and the second control branch based on failure monitoring results of the first clamping force command and the second clamping force command, and status monitoring results of the first communication link and the second communication link; when at least one of the first control branch and the second control branch is available, controlling the corresponding brake actuator according to the clamping force command transmitted by the available control branch; when neither the first control branch nor the second control branch is available, acquiring the pedal status signal transmitted by the independent hard-wired channel, and controlling the corresponding brake actuator according to the pedal status signal.

[0017] Furthermore, when both the first control branch and the second control branch are unavailable, local braking control based on the pedal status signal is enabled; when the pedal status signal indicates that the brake pedal is not depressed, no local braking clamping force is generated; when the pedal status signal indicates that the brake pedal is depressed, a local braking clamping force is generated and the corresponding brake actuator is controlled.

[0018] Furthermore, when the pedal status signal indicates that the brake pedal is depressed, the electromechanical braking devices at the wheel ends of the left and right front wheels of the vehicle are controlled to output preset non-zero clamping forces respectively; the target clamping forces of the electromechanical braking devices at the wheel ends of the left and right rear wheels of the vehicle are controlled to remain at zero.

[0019] This application provides a wheel-end electromechanical braking device in a third aspect, including a wheel-end controller and a brake actuator controlled by the wheel-end controller; the wheel-end controller includes a first communication interface, a second communication interface and an independent hard-wired input interface, the first communication interface is used to receive a first clamping force command, the second communication interface is used to receive a second clamping force command, and the independent hard-wired input interface is used to receive a pedal status signal output by a brake pedal switch; The wheel-end controller is configured to: perform failure monitoring on the first clamping force command and the second clamping force command, and monitor the status of the communication links connected to the first communication interface and the second communication interface, respectively; determine the availability status of the first control branch for transmitting the first clamping force command and the second control branch for transmitting the second clamping force command based on the failure monitoring results and the communication link status monitoring results; control the brake actuator according to the clamping force command transmitted by the available control branch when at least one of the first control branch and the second control branch is available; and control the brake actuator according to the pedal status signal obtained through the independent hard-wired input interface when neither the first control branch nor the second control branch is available.

[0020] Furthermore, the wheel-end controller stores the installation position identifier of the wheel-end electromechanical braking device and the degraded braking parameters corresponding to the installation position identifier; when both the first control branch and the second control branch are unavailable and the pedal status signal indicates that the brake pedal is depressed, the wheel-end controller calls the corresponding degraded braking parameters according to the installation position identifier and controls the brake actuator according to the degraded braking parameters.

[0021] Furthermore, when the installation position indicator indicates that the wheel-end electromechanical braking device is installed on the front axle of the vehicle, the degraded braking parameters include a preset non-zero clamping force; when the installation position indicator indicates that the wheel-end electromechanical braking device is installed on the rear axle of the vehicle, the degraded braking parameters include a zero target clamping force.

[0022] Compared with the prior art, the above technical solution has at least the following beneficial effects: by monitoring the status of the two clamping force commands and their communication links respectively, and the wheel-end controller determines the availability status of the two control branches accordingly, the wheel end can select the braking control source based on the actual availability of each control branch; when both control branches are unavailable, the pedal status signal output by the brake pedal switch is directly transmitted to the wheel-end controller through an independent hard-wired channel, enabling the wheel end to obtain the driver's braking operation status and control the corresponding brake actuator without relying on the first brake controller, the second brake controller and the corresponding communication link, thereby improving the independence and availability of wheel-end braking control when multiple conventional braking control sources are unavailable.

[0023] The above technical solution also has the following advantages: By determining whether the control branch is unavailable based on the clamping force command failure state and the communication link abnormal state, and enabling local braking control based on the pedal status signal in conjunction with the wheel end controller initialization state, the possibility of triggering local braking control when a single state abnormality occurs or the wheel end has not yet completed initialization can be reduced; By making the independent hard-wired channel bypass the brake controller and vehicle gateway, and making it independent of the two communication links in terms of physical wiring and electrical circuits, the impact of conventional control path failures on pedal status signal transmission can be reduced; By setting the target clamping force of each wheel end to zero when the pedal is not depressed, and adopting a differentiated control method of outputting a preset clamping force on the front axle and maintaining a zero target clamping force on the rear axle when the pedal is depressed, the braking force output under fault conditions can be limited while maintaining the driver's triggering conditions; By further limiting the front axle wheel ends to use the same preset fixed clamping force, and calling the corresponding degraded braking parameters based on the wheel end installation position identifier, each wheel end can implement local degraded braking control according to the preset wheel end position and braking parameters after being separated from the upper-level conventional braking control source. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the electromechanical braking system provided in an embodiment of this application; Figure 2 A schematic flowchart illustrating the electromechanical braking system control method provided in this application embodiment; Figure 3 This is a schematic diagram of the structure of the wheel-end electromechanical braking device provided in the embodiments of this application.

[0025] Among them: 110, first brake controller; 120, second brake controller; 130, brake pedal switch; 140, first communication link; 150, second communication link; 160, independent hard-wired channel; 170, wheel-end electromechanical braking device; 171, wheel-end controller; 172, brake actuator; 173, first communication interface; 174, second communication interface; 175, independent hard-wired input interface; 176, status monitoring unit; 177, control arbitration unit. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit the scope of protection of this application. Unless otherwise specified, the following embodiments and their technical features can be combined with each other.

[0027] Figure 1 This is a schematic diagram of the electromechanical braking system provided in an embodiment of this application. Figure 1 As shown, in one embodiment, the electromechanical braking system includes a first brake controller 110, a second brake controller 120, a first communication link 140, a second communication link 150, a brake pedal switch 130, and four wheel-end electromechanical braking devices respectively disposed at the left front wheel FL, right front wheel FR, left rear wheel RL, and right rear wheel RR of the vehicle.

[0028] Each wheel-end electromechanical braking device includes a wheel-end controller and a brake actuator controlled by the wheel-end controller. For ease of explanation, in this specific embodiment, any wheel-end electromechanical braking device is referred to as wheel-end electromechanical braking device 170, its wheel-end controller as wheel-end controller 171, and its brake actuator as brake actuator 172. Each wheel-end controller 171 only controls the brake actuator 172 in its respective wheel-end electromechanical braking device 170.

[0029] In one specific embodiment, the first brake controller 110 may correspond to the main brake controller or main domain controller in the vehicle braking system, and the second brake controller 120 may correspond to the auxiliary brake controller or backup domain controller in the vehicle braking system. The first communication link 140 may adopt a first private CAN communication link, and the second communication link 150 may adopt a second private CAN communication link.

[0030] The first brake controller 110 is communicatively connected to four wheel end controllers 171 via a first communication link 140, and is used to send a first clamping force command to each wheel end controller 171. The first brake controller 110, the first communication link 140, and the first clamping force command transmitted via the first communication link 140 form a first control branch.

[0031] The second brake controller 120 is connected to each of the four wheel end controllers 171 via a second communication link 150, and is used to send a second clamping force command to each wheel end controller 171. The second brake controller 120, the second communication link 150, and the second clamping force command transmitted via the second communication link 150 form a second control branch.

[0032] In this application, "control branch available" means that the corresponding control branch can provide clamping force commands to the wheel end controller 171 that can be used for normal braking control; correspondingly, "control branch unavailable" means that the control branch cannot continue to serve as an effective control source for normal wheel end braking control due to the failure of the clamping force command itself, the abnormality of the communication link, or a combination of the two.

[0033] Under normal operating conditions, the first control branch and the second control branch constitute redundant braking control sources. In one specific embodiment, the first control branch can be configured as the priority control branch, and the second control branch can be configured as the backup control branch. When both the first and second control branches are available, each wheel-end controller 171 can preferentially use the first clamping force command to control the corresponding brake actuator 172; when the first control branch is unavailable but the second control branch is available, each wheel-end controller 171 uses the second clamping force command to control the corresponding brake actuator 172; when the second control branch is unavailable but the first control branch is still available, each wheel-end controller 171 continues to control the corresponding brake actuator 172 according to the first clamping force command.

[0034] In other embodiments, when both the first control branch and the second control branch are available, one of the control branches can be selected as the current effective control source according to a preset priority or a preset control source arbitration rule. The focus of this application is not on limiting the specific priority between the two available control branches under normal conditions, but on the fact that the wheel-end controller 171 can determine the availability status of the two control branches separately, and switch to local braking control independent of the two control branches after both control branches become unavailable.

[0035] The brake pedal switch 130 is located at the brake pedal assembly of the vehicle and is used to output a pedal status signal indicating whether the brake pedal is depressed. The brake pedal switch 130 is directly connected to the four wheel end controllers 171 through independent hard-wired channels 160, so that the pedal status signal can be directly input to each wheel end controller 171.

[0036] The independent hard-wired channel 160 does not pass through the first brake controller 110, the second brake controller 120, or the vehicle gateway node, and the independent hard-wired channel 160 is physically independent of the first communication link 140 and the second communication link 150 in terms of wiring and electrical circuitry. Therefore, even if neither the first control branch nor the second control branch can continue to provide effective clamping force commands, the wheel-end controller 171 can still obtain the pedal status signal output by the brake pedal switch 130 via the independent hard-wired channel 160.

[0037] It should be noted that the independent hard-wired channel 160 is used to input the pedal status signal to the wheel-end controller 171, rather than to directly drive the brake actuator 172. After receiving the pedal status signal, the wheel-end controller 171 determines the local target clamping force based on the current available state of the control branch and the pedal status, and then controls the corresponding brake actuator 172 based on the determined local target clamping force.

[0038] In one embodiment, the brake pedal switch 130 can output two voltage levels: high and low. For example, the first voltage level can be predefined as the brake pedal not being depressed, and the second voltage level can be predefined as the brake pedal being depressed. The specific high and low voltage level correspondence can be determined according to the vehicle electrical system design and is not limited to a specific high and low voltage level correspondence.

[0039] The independent hardwire channel 160 can consist of one or more hardwires. For example, it can use a single hardwire with a shielding structure, or it can use two independent redundant hardwires. Regardless of the implementation, the independent hardwire channel 160 bypasses the first brake controller 110 and the second brake controller 120 and is directly connected to the digital input terminals of each wheel-end controller 171. The digital input terminals can be configured with hardware filtering circuits to reduce the impact of transient interference on pedal status recognition.

[0040] Each wheel end controller 171 receives the first clamping force command and the second clamping force command respectively, and performs failure monitoring on the first clamping force command and the second clamping force command, while monitoring the communication status of the first communication link 140 and the second communication link 150.

[0041] Failure monitoring of clamping force commands may include at least command update status monitoring. In one specific embodiment, the wheel end controller 171 cyclically reads the first clamping force command and the second clamping force command at a preset detection cycle. For example, the preset detection cycle may be 10 ms. When the first clamping force command has not been updated for a preset number of consecutive detection cycles, it can be determined that the first clamping force command has failed; when the second clamping force command has not been updated for a preset number of consecutive detection cycles, it can be determined that the second clamping force command has failed.

[0042] For example, the preset number can be 3, meaning that if no new data is obtained for the corresponding clamping force command for 3 consecutive detection cycles, the clamping force command is determined to be invalid. The above 10 ms and 3 detection cycles are only a specific example. In actual applications, they can be set according to the normal sending cycle of the clamping force command, system response requirements, and communication fault tolerance requirements.

[0043] In addition to determining whether a command is invalid based on its update status, the validity of a clamping force command can also be determined by combining the command validity flag, data integrity verification results, or message verification results. For example, if a clamping force command message is received but fails the preset data integrity verification, the corresponding clamping force command can be determined to be invalid.

[0044] The status of the first communication link 140 and the second communication link 150 can be monitored by the communication interface or communication controller corresponding to the wheel-end controller 171. In one embodiment, when the first communication link 140 experiences a communication timeout, it is determined that the first communication link 140 is abnormal; when the second communication link 150 experiences a communication timeout, it is determined that the second communication link 150 is abnormal.

[0045] The communication timeout refers to the failure to receive a preset message that the corresponding control branch should periodically send within a preset communication monitoring period. Communication anomalies can also include the communication controller entering a bus-off state, i.e., a Bus-Off state. Therefore, when a communication timeout occurs on a corresponding communication link or the corresponding communication interface enters a Bus-Off state, the communication link can be identified as abnormal.

[0046] Based on the failure monitoring results of the clamping force command and the status monitoring results of the communication link, the wheel end controller 171 determines the availability status of the first control branch and the second control branch, respectively.

[0047] In the first method for determining if a control branch is unavailable, the first control branch is determined to be unavailable when either the first clamping force command fails or the first communication link 140 malfunctions; the second control branch is determined to be unavailable when either the second clamping force command fails or the second communication link 150 malfunctions.

[0048] When using this determination method, if a control branch can no longer continuously provide the wheel-end controller 171 with an effective clamping force command that can be used for normal braking control, the control branch can be determined as unusable.

[0049] In the second method for determining if a control branch is unavailable, the first control branch is determined to be unavailable when the first clamping force command fails and the first communication link 140 is abnormal; the second control branch is determined to be unavailable when the second clamping force command fails and the second communication link 150 is abnormal.

[0050] Compared to the first determination method mentioned above, the second determination method uses both the clamping force command status and the communication link status for confirmation, which can reduce the possibility of control source switching caused by a single transient status anomaly.

[0051] The first and second methods for determining the unavailability of control branches can be used as different system configuration methods, and it is not required that both methods be used simultaneously within the same operating cycle.

[0052] When at least one of the first and second control branches is available, the wheel-end controller 171 continues to control the corresponding brake actuator 172 according to the clamping force command transmitted by the available control branch. In this state, the pedal status signal transmitted by the independent hardwire channel 160 can remain as a backup input and is not used as the local clamping force control source for the current brake actuator 172.

[0053] When both the first control branch and the second control branch are determined to be unavailable, the wheel end controller 171 further determines whether it has completed initialization.

[0054] In one embodiment, the wheel-end controller 171 can determine its initialization status based on the initialization completion flags of the underlying hardware and control program, such as determining whether the wheel-end controller 171 has completed initialization based on the power-on self-test completion flag. Since the communication buffer, communication interface, and state variables may not have been established yet during the vehicle power-on or wheel-end controller 171 reset process, the inability to obtain a valid clamping force command at this time should not be used as the basis for entering local braking control.

[0055] Therefore, when both the first and second control branches are unavailable, but the wheel-end controller 171 has not yet completed initialization, it is prohibited to control the corresponding brake actuator 172 based on the pedal status signal.

[0056] When both the first and second control branches are unavailable and the wheel-end controller 171 has been initialized, enable local braking control based on the pedal state signal.

[0057] In other words, the state where both control branches are unavailable is used to determine whether local braking control is allowed, while the pedal status signal output by the brake pedal switch 130 is used to further determine whether a non-zero local braking clamping force is actually generated. Thus, the control branch failure state and the actual braking action form a two-level judgment relationship.

[0058] When the pedal status signal indicates that the brake pedal is not depressed, the four wheel end controllers 171 set the corresponding local target clamping force to zero, so that each brake actuator 172 does not generate a non-zero clamping force based on local degradation control.

[0059] When the pedal status signal indicates that the brake pedal is depressed, the wheel end controllers 171 corresponding to the left front wheel FL and the right front wheel FR set their respective local target clamping forces to preset non-zero clamping forces; the wheel end controllers 171 corresponding to the left rear wheel RL and the right rear wheel RR set their respective local target clamping forces to zero.

[0060] Thus, when both the first and second control branches are unavailable, a preset braking clamping force is generated at the front axle wheel end, while the rear axle wheel end maintains zero target clamping force, forming a local braking control mode that differentiates between the front and rear axles.

[0061] In another embodiment, when both the first and second control branches are unavailable, and the pedal status signal indicates that the brake pedal is depressed, the wheel-end controllers 171 corresponding to the left front wheel FL, right front wheel FR, left rear wheel RL, and right rear wheel RR can all set their corresponding local target clamping forces to preset non-zero clamping forces, so that both the front and rear axles of the vehicle generate local degraded braking forces. The preset non-zero clamping forces corresponding to each wheel end can be the same, or they can be set separately according to the wheel-end mounting position; for example, the preset non-zero clamping forces corresponding to the front axle and the rear axle can use different calibration values. Each preset non-zero clamping force can be calibrated according to vehicle parameters, brake structure parameters, and preset degraded braking requirements.

[0062] Furthermore, the wheel end controllers 171 corresponding to the left front wheel FL and the right front wheel FR can set their respective target clamping forces to the same preset fixed clamping force, and maintain the preset fixed clamping force while the pedal status signal continuously indicates that the brake pedal is depressed.

[0063] In one specific embodiment, the preset clamping force of the wheel-end electromechanical braking devices 170 corresponding to the left front wheel FL and the right front wheel FR can each be set to 15kN. 15kN is a specific calibration example. In other embodiments, other non-zero clamping forces can also be determined based on the vehicle's weight, brake structure parameters, and preset degraded braking capacity.

[0064] When the pedal status signal changes from indicating that the brake pedal is depressed to indicating that the brake pedal is not depressed, the local target clamping force corresponding to the front axle can be reset to zero.

[0065] Figure 2 This is a schematic flowchart illustrating the electromechanical braking system control method provided in an embodiment of this application. Figure 2 As shown, in one embodiment, each wheel-end controller 171 continuously monitors the first clamping force command and the second clamping force command, and monitors the status of the first communication link 140 and the second communication link 150. Subsequently, based on the failure monitoring results of the first clamping force command and the second clamping force command, and the status monitoring results of the first communication link 140 and the second communication link 150, the availability status of the first control branch and the second control branch are determined respectively.

[0066] The system determines whether both the first and second control branches are unavailable. If the determination is negative, meaning at least one of the first and second control branches is still available, the corresponding brake actuator 172 is controlled according to the clamping force command transmitted by the available control branch. After completing the current control cycle, the system returns to monitoring the clamping force command and communication link status. If both the first and second control branches are unavailable, the system further determines whether the wheel end controller 171 has completed initialization.

[0067] When the wheel-end controller 171 has not completed initialization, it is prohibited to control the corresponding brake actuator 172 based on the pedal status signal, and the control branch status monitoring continues. When the wheel-end controller 171 has completed initialization, it obtains the pedal status signal output by the brake pedal switch 130 through the independent hard-wired channel 160.

[0068] The brake pedal is determined based on the pedal status signal. When the brake pedal is not depressed, the target clamping force at each wheel end is set to zero. When the brake pedal is depressed, the target clamping forces corresponding to the left front wheel FL and the right front wheel FR are set to preset non-zero clamping forces, and the target clamping forces corresponding to the left rear wheel RL and the right rear wheel RR are set to zero.

[0069] After determining the target clamping force for each wheel end, the wheel end controller 171 controls the corresponding brake actuator 172 according to the target clamping force.

[0070] After completing the current wheel-end braking control, the control process returns to the monitoring process of the first clamping force command, the second clamping force command, and the status of the first communication link 140 and the second communication link 150, thus forming a continuous loop of status monitoring and control source selection process.

[0071] Therefore, during vehicle operation, the wheel-end controller 171 can continuously monitor the availability status of the two normal control branches. When at least one control branch is available, braking control based on the normal clamping force command is maintained first; when both control branches are unavailable and the local control enable condition is met, the system switches to the pedal status signal obtained through the independent hard-wired channel 160 as the basis for local braking triggering.

[0072] In subsequent monitoring cycles, if the first or second control branch is detected to meet the preset availability conditions again, normal braking control can be re-implemented based on the clamping force command transmitted by the available control branch. The specific control recovery confirmation duration or number of recovery judgments can be determined according to the actual system configuration.

[0073] Figure 3 This is a schematic diagram of the wheel-end electromechanical braking device provided in an embodiment of this application. Figure 3 As shown, the wheel-end electromechanical braking device 170 includes a wheel-end controller 171 and a brake actuator 172 controlled by the wheel-end controller 171. The wheel-end controller 171 includes a first communication interface 173, a second communication interface 174, an independent hardwired input interface 175, a status monitoring unit 176, and a control arbitration unit 177. The status monitoring unit 176 and the control arbitration unit 177 represent the internal functional division of the wheel-end controller 171. They can be implemented by the same processor in the wheel-end controller 171 executing different program modules, or they can be implemented in other ways that can achieve the corresponding functions according to the specific hardware architecture. It is not required that the status monitoring unit 176 and the control arbitration unit 177 correspond to separate physical control chips.

[0074] The first communication interface 173 is connected to the first communication link 140 and is used to receive the first clamping force command sent by the first brake controller 110 through the first communication link 140.

[0075] The second communication interface 174 is connected to the second communication link 150 and is used to receive the second clamping force command sent by the second brake controller 120 through the second communication link 150.

[0076] The independent hard-wire input interface 175 is connected to the independent hard-wire channel 160 and is used to receive the pedal status signal output by the brake pedal switch 130.

[0077] The first communication interface 173 and the second communication interface 174 respectively provide information related to the first clamping force command and the second clamping force command to the status monitoring unit 176. Based on the received command status and the communication status corresponding to the first communication interface 173 and the second communication interface 174, the status monitoring unit 176 monitors the status of the first clamping force command, the second clamping force command, and the corresponding communication links, and determines the availability status of the first control branch and the second control branch.

[0078] The status monitoring unit 176 provides the available status of the first control branch and the second control branch to the control arbitration unit 177.

[0079] The first communication interface 173 and the second communication interface 174 can also provide the received first clamping force command and second clamping force command to the control arbitration unit 177 through the data path inside the wheel end controller 171. The internal data path can be implemented using a processor internal bus, a shared memory area, a message buffer, or other structures that can transmit clamping force commands inside the wheel end controller 171.

[0080] The independent hard-wired input interface 175 provides the pedal status signal to the control arbitration unit 177.

[0081] Therefore, the control arbitration unit 177 can obtain the first clamping force command, the second clamping force command, the availability status of the first control branch and the second control branch, and the pedal status signal, and determine the target clamping force for controlling the brake actuator 172 based on the above information.

[0082] When at least one of the first control branch and the second control branch is available, the control arbitration unit 177 selects the clamping force command transmitted by the available control branch as the target control input of the brake actuator 172.

[0083] When both the first and second control branches are unavailable, the control arbitration unit 177 no longer relies on the clamping force commands provided by the two normal control branches, but instead determines the local target clamping force based on the pedal status signal obtained through the independent hard-wired input interface 175.

[0084] The control arbitration unit 177 outputs a corresponding braking control signal based on the determined target clamping force, and the wheel end controller 171 controls the brake actuator 172 to generate the corresponding braking clamping force.

[0085] Therefore, the first communication interface 173, the second communication interface 174, and the independent hard-wired input interface 175 are only used to input control information from different sources into the wheel end controller 171. The actual control output acting on the brake actuator 172 is generated by the wheel end controller 171 after completing the control branch status judgment and control source arbitration. The independent hard-wired channel 160 does not directly drive the brake actuator 172.

[0086] In one embodiment, the wheel-end controller 171 also stores an installation position identifier indicating the current installation position of the wheel-end electromechanical braking device 170 and degraded braking parameters corresponding to the installation position identifier.

[0087] The mounting position markings can at least indicate whether the current wheel-end electromechanical braking device 170 is located on the front or rear axle of the vehicle. In a further embodiment, the mounting position markings can use FL, FR, RL, and RR to represent the positions of the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0088] Degraded braking parameters can be pre-stored in the non-volatile storage area, parameter configuration area, or other storage area that can be read by the control program in the wheel end controller 171.

[0089] When both the first and second control branches are unavailable, and the pedal status signal indicates that the brake pedal is depressed, the wheel end controller 171 reads the corresponding degraded braking parameters according to its own installation position identifier, and determines the local target clamping force based on the degraded braking parameters.

[0090] When the installation position indicator indicates that the current wheel-end electromechanical braking device 170 is located on the front axle of the vehicle, the corresponding degraded braking parameters include a preset non-zero clamping force. The preset non-zero clamping force can further be a preset fixed clamping force.

[0091] When the installation position indicator indicates that the current wheel-end electromechanical braking device 170 is located on the rear axle of the vehicle, the corresponding degraded braking parameters include zero target clamping force.

[0092] For example, for the two front axle wheel-end electromechanical brake devices 170 with installation positions marked FL and FR, a fixed clamping force parameter of 15kN can be configured respectively; for the two rear axle wheel-end electromechanical brake devices 170 with installation positions marked RL and RR, a zero target clamping force parameter can be configured.

[0093] In another embodiment, when the installation position indicator indicates that the current wheel-end electromechanical braking device 170 is located on the rear axle of the vehicle, the corresponding degraded braking parameters may also include a preset non-zero clamping force, so that the wheel-end electromechanical braking devices 170 corresponding to the front axle and the rear axle can output a non-zero clamping force under local braking control.

[0094] After adopting the above parameter configuration method, the four wheel-end electromechanical braking devices 170 can adopt the same or similar wheel-end controller hardware architecture, and determine the braking strategy that the current wheel end should execute under the local braking control state through the locally configured installation position identifier and degraded braking parameters.

[0095] In one embodiment, neither the first control branch nor the second control branch can be used to enable local braking control. The pedal status signal output by the brake pedal switch 130 is used to determine whether non-zero clamping force control is actually executed, while the installation position identifier and corresponding degraded braking parameters are used to determine the specific local target clamping force used at each wheel end. Thus, the determination of the control source status, the acquisition of the driver's pedal status, and the selection of wheel end braking parameters can be completed locally at the wheel end.

[0096] It should be noted that the 10 ms detection cycle, three consecutive detection cycles, and 15 kN clamping force mentioned above are specific implementation parameters used to illustrate the technical solution of this application. Without changing the basic control relationship of control branch status monitoring, independent hard-wired pedal status input, and wheel-end local arbitration described in this application, the above parameters can be adjusted accordingly based on the specific vehicle model and control system configuration.

[0097] Similarly, the first communication link 140 and the second communication link 150 are described in this embodiment using a private CAN communication link, which is mainly used to establish independent normal braking control communication paths between the first brake controller 110, the second brake controller 120 and the wheel end controller 171 respectively.

[0098] This application monitors the availability of two normal control branches at the wheel-end controller 171 and configures a pedal status signal input path independent of the two normal control branches. This enables the wheel-end controller 171 to implement local braking control based on the driver's actual pedal operation state when both normal control branches are unavailable. At the same time, by configuring different local target clamping forces corresponding to the front and rear axles, each wheel end can still be controlled according to the preset degraded braking mode after being disconnected from the upper normal control source.

[0099] The above embodiments are only for illustrating the technical concept and features of this application, and are intended to enable those skilled in the art to understand the content of this application and implement it accordingly. They should not be used to limit the scope of protection of this application. It is obvious to those skilled in the art that this application is not limited to the details of the above exemplary embodiments, and that this application can be implemented in other specific forms without departing from the spirit or basic characteristics of this application. Therefore, all embodiments should be considered exemplary and non-limiting, and all changes within the meaning and scope of equivalent elements of the technical features of this application are included within this application.

Claims

1. An electromechanical braking system, characterized in that, It includes a first brake controller, a second brake controller, a first communication link, a second communication link, a brake pedal switch, and four wheel-end electromechanical braking devices; Each of the aforementioned wheel-end electromechanical braking devices includes a wheel-end controller and a brake actuator controlled by the wheel-end controller; The first brake controller communicates with each of the wheel end controllers via the first communication link to send a first clamping force command to each of the wheel end controllers, forming a first control branch; The second brake controller communicates with each of the wheel end controllers via the second communication link to send a second clamping force command to each of the wheel end controllers, forming a second control branch; The brake pedal switch is directly connected to each of the wheel end controllers via an independent hard-wired channel to output a pedal status signal to each of the wheel end controllers; Each of the wheel-end controllers is configured to at least: The first clamping force command is received through the first communication link, and the second clamping force command is received through the second communication link; Failure monitoring is performed on the first clamping force command and the second clamping force command, and the status of the first communication link and the status of the second communication link are monitored; The availability status of the first control branch and the second control branch is determined based on the failure monitoring results and the monitoring results. When neither the first control branch nor the second control branch is available, the corresponding brake actuator is controlled according to the pedal status signal.

2. The electromechanical braking system according to claim 1, characterized in that, If the first clamping force command fails or the first communication link is abnormal, it is determined that the first control branch is unavailable; If the second clamping force command fails or the second communication link is abnormal, the second control branch is determined to be unavailable.

3. The electromechanical braking system according to claim 1, characterized in that, When the first clamping force command fails and the first communication link is abnormal, it is determined that the first control branch is unavailable; When the second clamping force command fails and the second communication link is abnormal, it is determined that the second control branch is unavailable.

4. The electromechanical braking system according to claim 1, characterized in that, Each of the wheel-end controllers is further configured to: The update status of the first clamping force command and the second clamping force command is detected according to a preset detection cycle. If the first clamping force command has not been updated for a preset number of consecutive detection cycles, the first clamping force command is determined to be invalid. If the second clamping force command has not been updated for a preset number of consecutive detection cycles, the second clamping force command is determined to be invalid. Monitor the communication status of the first communication link and the second communication link, and determine that the first communication link is abnormal when a communication timeout occurs or the bus is shut down. Determine that the second communication link is abnormal when a communication timeout occurs or the bus is shut down.

5. The electromechanical braking system according to claim 1, characterized in that, Each of the wheel-end controllers is further configured to: After determining that both the first control branch and the second control branch are unavailable, determine whether the current-round controller has completed initialization; Once the end controller has completed initialization, it is permissible to control the corresponding brake actuator based on the pedal status signal. If the end controller has not completed initialization, it is prohibited to control the corresponding brake actuator based on the pedal status signal.

6. The electromechanical braking system according to claim 1, characterized in that, The independent hardwired channel does not pass through the first brake controller, the second brake controller, and the vehicle gateway node, and the independent hardwired channel is independent of the first communication link and the second communication link in terms of physical wiring and electrical circuit.

7. The electromechanical braking system according to any one of claims 1 to 6, characterized in that, The four wheel-end electromechanical braking devices are respectively installed on the left front wheel, right front wheel, left rear wheel and right rear wheel of the vehicle; When both the first control branch and the second control branch are unavailable: When the pedal status signal indicates that the brake pedal is not depressed, each wheel end controller sets the corresponding target clamping force to zero. When the pedal status signal indicates that the brake pedal is depressed, the wheel end controllers located on the left front wheel and the right front wheel respectively set the corresponding target clamping force to a preset non-zero clamping force, and the wheel end controllers located on the left rear wheel and the right rear wheel respectively set the corresponding target clamping force to zero.

8. The electromechanical braking system according to claim 7, characterized in that, The wheel-end controllers installed on the left front wheel and the right front wheel set the corresponding target clamping force to the same preset fixed clamping force when the pedal status signal indicates that the brake pedal is depressed, and maintain the preset fixed clamping force while the pedal status signal continues to indicate that the brake pedal is depressed.

9. The electromechanical braking system according to claim 8, characterized in that, The preset clamping force corresponding to the electromechanical braking devices installed on the wheel ends of the left front wheel and the right front wheel is 15kN.

10. A control method for an electromechanical braking system, applied to the electromechanical braking system according to any one of claims 1 to 9, characterized in that, include: The wheel end controllers determine the availability status of the first control branch and the second control branch based on the failure monitoring results of the first clamping force command and the second clamping force command, as well as the status monitoring results of the first communication link and the second communication link. When at least one of the first control branch and the second control branch is available, the corresponding brake actuator is controlled according to the clamping force command transmitted by the available control branch; When both the first control branch and the second control branch are unavailable, the pedal status signal transmitted by the independent hardwire channel is acquired, and the corresponding brake actuator is controlled according to the pedal status signal.

11. The control method according to claim 10, characterized in that, After both the first control branch and the second control branch become unavailable, enable local braking control based on the pedal state signal; When the pedal status signal indicates that the brake pedal is not depressed, no local braking clamping force is generated; When the pedal status signal indicates that the brake pedal is depressed, a local braking clamping force is generated and the corresponding brake actuator is controlled.

12. The control method according to claim 11, characterized in that, When the pedal status signal indicates that the brake pedal is depressed... The electromechanical braking devices located at the wheel ends of the left and right front wheels of the vehicle output preset non-zero clamping forces respectively; The target clamping force of the electromechanical braking devices located at the wheel ends of the left and right rear wheels of the vehicle is kept at zero.

13. A wheel-end electromechanical braking device, characterized in that, Includes a wheel-end controller and a brake actuator controlled by the wheel-end controller; The wheel-end controller includes a first communication interface, a second communication interface, and an independent hard-wired input interface. The first communication interface is used to receive a first clamping force command, the second communication interface is used to receive a second clamping force command, and the independent hard-wired input interface is used to receive a pedal status signal output by the brake pedal switch. The wheel-end controller is configured to: Failure monitoring is performed on the first clamping force command and the second clamping force command, and the status of the communication links connected to the first communication interface and the second communication interface are monitored respectively; Based on the failure monitoring results and the communication link status monitoring results, the availability status of the first control branch used to transmit the first clamping force command and the second control branch used to transmit the second clamping force command are determined respectively. When at least one of the first control branch and the second control branch is available, the brake actuator is controlled according to the clamping force command transmitted by the available control branch; When both the first control branch and the second control branch are unavailable, the brake actuator is controlled according to the pedal status signal obtained through the independent hard-wired input interface.

14. The wheel-end electromechanical braking device according to claim 13, characterized in that, The wheel-end controller stores the installation position identifier of the wheel-end electromechanical braking device and the degraded braking parameters corresponding to the installation position identifier. When both the first control branch and the second control branch are unavailable and the pedal status signal indicates that the brake pedal is depressed, the wheel end controller calls the corresponding degraded braking parameters according to the installation position identifier, and controls the brake actuator according to the degraded braking parameters.

15. The wheel-end electromechanical braking device according to claim 14, characterized in that, When the installation position indicator indicates that the wheel-end electromechanical braking device is installed on the front axle of the vehicle, the degraded braking parameters include a preset non-zero clamping force; When the installation location identifier indicates that the wheel-end electromechanical braking device is installed on the rear axle of the vehicle, the degraded braking parameters include zero target clamping force.

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