A distributed drive-brake integrated control system and fault processing method for intelligent driving

Abstract

The application discloses a kind of distributed drive-brake integration control systems and fault processing methods for intelligent driving, control system includes wheel hub motor, electronic mechanical brake system, brake pedal feeling simulator, automatic driving system control unit, drive-brake integration control unit and power supply battery, wherein wheel hub motor is provided with four, four wheel hub motors are respectively assembled in the wheel hub of four drive wheels of vehicle body, fault processing method is: first step, open fault driving function;Second step, do not intervene vehicle travel;Third step, set each wheel target clamping force;Fourth step, realize anti-lock braking control;Fifth step, when the processing of first CAN communication module failure;Sixth step, when the control mode of second CAN communication module failure.Affirmative effect: meet the needs of intelligent driving and intelligent chassis technology "layout flexibility, architecture compatibility, control integration is good".

Description

Technical Field

[0001] This invention relates to an integrated drive and braking control system and a fault handling method, and particularly to a distributed integrated drive and braking control system and a fault handling method for intelligent driving. Background Technology

[0002] Currently, electrification, connectivity, and intelligence are the main directions for the future development of the new energy vehicle industry. Intelligent connected vehicles will be widely used in China, and the development prospects of advanced autonomous vehicles are very broad. At the same time, Level 3 and above autonomous driving also puts forward new and higher requirements for vehicle chassis systems, requiring them to have the characteristics of "layout flexibility, architecture compatibility, and control integration". Intelligent chassis systems decouple the mechanical connection between the driver's control mechanism and the actuators of various chassis subsystems, and control the chassis to perform actions through electrical signals. They have the characteristics of faster response, more precise following, and more stable control, making them the best platform to meet the performance requirements of Level 3 and above autonomous driving systems. Therefore, autonomous driving and intelligent chassis are complementary and mutually reinforcing.

[0003] The 2022 roadmap for intelligent chassis in passenger vehicles and electric vehicles outlines the path for intelligent chassis development. Intelligent chassis are evolving towards distributed actuators and integrated control, with the goal of achieving integrated control of X and Y-direction drive and braking by 2025. To meet these requirements, drive system configurations are shifting from centralized to distributed drive, with in-wheel motors (IWM) representing the ultimate form of distributed drive. IWMs increase the flexibility of the vehicle's powertrain layout and offer higher torque response speed and accuracy, significantly improving vehicle handling and stability. They also enable electromechanical braking for higher energy recovery efficiency and leverage the braking potential of in-wheel motors. Simultaneously, braking systems are evolving from traditional hydraulic braking systems towards brake-by-wire systems, enabling independent control of four-wheel braking. Electromechanical braking (EMB) represents the ultimate form of brake-by-wire, with a simpler and clearer structure. It completely eliminates hydraulic braking units, relying entirely on electronic signals for pedal and actuator communication, resulting in faster braking response. Furthermore, it can integrate with other chassis systems to achieve comprehensive chassis control, making it a truly full-line braking system. Therefore, in the context of the development of intelligent driving and intelligent chassis, for the ultimate configuration of distributed chassis with in-wheel motor (IWM) + electromechanical braking system (EMB), it is necessary to design a reasonable control system to give full play to the performance advantages of distributed drive and braking of in-wheel motor (IWM) and electromechanical braking system (EMB), and to design a reasonable integrated drive and braking collaborative control algorithm to realize the integrated drive and braking control of distributed chassis.

[0004] To address the aforementioned issues, this invention proposes a distributed integrated drive and braking control system for intelligent driving. Furthermore, it proposes a control strategy architecture for the key module of the proposed control system—the integrated drive and braking control unit. Simultaneously, to leverage the braking energy recovery advantages and wheel hub motor braking potential of the key module of this control strategy architecture—the electromechanical cooperative braking control module—a cooperative braking control strategy is designed. Finally, to ensure vehicle braking safety, a fault handling method is proposed for the integrated drive and braking control unit and for communication failures. Summary of the Invention

[0005] The main objective of this invention is to design a reasonable control system to leverage the performance advantages of the distributed drive and braking system of the hub motor and electromechanical braking system, and to design a reasonable integrated drive and braking collaborative control algorithm to achieve integrated drive and braking control of the distributed chassis.

[0006] Another objective of this invention is to provide a fault handling method for integrated drive and braking control unit and communication failure.

[0007] In order to achieve the above objectives and solve the above problems, the present invention provides a distributed integrated drive and braking control system and fault handling method for intelligent driving.

[0008] The distributed integrated drive and braking control system for intelligent driving provided by this invention includes hub motors, electromechanical braking systems, a brake pedal feel simulator, an autonomous driving system control unit, an integrated drive and braking control unit, and a power supply battery. Four hub motors are provided, each mounted in the hub of one of the four drive wheels of the vehicle body. Each hub motor is connected to a hub motor control unit. Four electromechanical braking systems are also provided, each mounted on the brake caliper of one of the four drive wheels of the vehicle body. Each electromechanical braking system is connected to an electromechanical braking control unit. A push rod on the brake pedal feel simulator is equipped with a push rod force sensor, which is connected to the integrated drive and braking control unit. The push rod force sensor can transmit the collected data to the drive and brake integrated control unit in real time. The autonomous driving system control unit is connected to the drive and brake integrated control unit. The drive and brake integrated control unit is also connected to a first CAN communication module and a second CAN communication module. The first CAN communication module is connected to the hub motor control unit and the electromechanical brake control unit mounted on the two drive wheels at the front of the vehicle body, respectively. The second CAN communication module is connected to the hub motor control unit and the electromechanical brake control unit mounted on the two drive wheels at the rear of the vehicle body, respectively. The power supply battery is connected to the aforementioned electromechanical brake control unit and electromechanical brake system and provides power to the electromechanical brake control unit and electromechanical brake system.

[0009] Each of the four drive wheels of the vehicle is equipped with a wheel speed sensor. Each wheel speed sensor is connected to an electromechanical braking control unit mounted on the brake caliper of that wheel. The wheel speed sensors can transmit the collected data to the electromechanical braking control unit in real time.

[0010] The brake pedal feel simulator is equipped with a switch signal sensor at the connection between the brake pedal device and the push rod. The switch signal sensor is connected to the electromechanical brake control unit mounted on the brake calipers of the four drive wheels of the vehicle body. The switch signal sensor can transmit the collected data to the electromechanical brake control unit mounted on the four drive wheel brake calipers in real time, so that the electromechanical brake control unit can control the operation of the electromechanical braking system. The switch signal sensor is also connected to the integrated drive and brake control unit, and the switch signal sensor can transmit the collected data to the integrated drive and brake control unit in real time.

[0011] A gateway module is installed on the connection line between the autonomous driving system control unit and the integrated drive and braking control unit.

[0012] Two batteries are installed for power supply.

[0013] The aforementioned hub motor, electromechanical braking system, brake pedal feel simulator, autonomous driving system control unit, integrated drive and brake control unit, power supply battery, hub motor control unit, electromechanical braking control unit, push rod force sensor, wheel speed sensor, switch signal sensor, and gateway module are all assemblies of existing equipment; therefore, specific models and specifications are not detailed.

[0014] The working principle of the distributed integrated drive and braking control system for intelligent driving provided by this invention is as follows:

[0015] The distributed integrated drive-brake control system for intelligent driving provided by this invention includes a brake pedal device mechanically connected to a brake pedal feel simulator. The brake pedal device is used by the driver to input braking intent, and the brake pedal feel simulator provides the driver's braking sensation. A push rod force sensor is installed between the two to collect the brake pedal push rod force and thus identify the driver's braking intent. Additionally, the brake pedal device is connected to a switch signal sensor to collect the brake pedal switch signal and thus identify whether the driver is braking. The push rod force sensor and the switch signal sensor can form mutual backups, and both are hardwired to the integrated drive-brake control unit. The main function of the integrated drive-brake control unit is to analyze the signals from the push rod force sensor and the switch signal sensor to identify the driver's driving intent through an algorithm. Then, it integrates the driving intent input from the autonomous driving system control unit and calculates and outputs the target braking torque of each drive wheel's IWM and EMB using an internal algorithm. Furthermore, the switch signal sensor is also hardwired to the electromechanical braking control units mounted on the four drive wheels, enabling these four wheel-end electromechanical braking control units to receive driver braking signals. The pedal switch signal is used for subsequent fault handling functions. Each drive wheel's electromechanical braking control unit is hardwired to its corresponding electromechanical braking system. These four control units convert the target electromechanical braking torque received from the integrated drive-brake control unit into a target clamping force and control the connected electromechanical braking system to respond. Each of the four electromechanical braking systems feeds back its internal Hall sensor signal to its connected control unit. Each drive wheel's electromechanical braking control unit is also hardwired to its corresponding wheel speed sensor to receive wheel speed signals from the four drive wheels for subsequent fault handling functions. Furthermore, each of the four drive wheels' hub motors is connected to a hub motor control unit. These control units control their respective hub motors to respond to the target electromechanical braking torque received from the integrated drive-brake control unit, and each hub motor feeds back its built-in wheel speed sensor signal to its connected control unit. Two power supply batteries provide redundant power to the electromechanical braking systems on the four drive wheels, ensuring normal braking even if any power supply fails.

[0016] From a communication perspective, the connection relationships and functions of the above systems are described as follows: the autonomous driving system control unit and the integrated drive and brake control unit communicate through a gateway module. The autonomous driving system control unit sends its braking intention-related signals to the gateway module via Ethernet. The gateway module converts these signals into CAN communication signals and sends them to the integrated drive and brake control unit. The integrated drive and brake control unit is connected to a first CAN communication module and a second CAN communication module. The integrated drive and brake control unit supports two CAN communication channels. The integrated drive and brake control unit sends electromechanical braking torque and electric motor braking torque to the electromechanical brake control unit and wheel hub motor control unit on the four drive wheels through the two CAN communication channels, respectively.

[0017] During normal operation, the autonomous driving system control unit perceives the surrounding road and driving environment, determines the braking control intention signal for the vehicle, and inputs it to the integrated drive-brake control unit. Simultaneously, the driver, based on their own judgment of the road and environment, depresses the brake pedal. The push-rod force sensor and switch signal sensor collect sensor signals and input them to the integrated drive-brake control unit. The integrated drive-brake control unit comprehensively processes the braking intentions of the autonomous driving system and the driver, and calculates the electromechanical braking torque and electric motor torque for each drive wheel according to internal algorithms. These are then output to the electromechanical braking control units and wheel motor control units mounted on the four drive wheels, respectively. After receiving the signal, the braking unit enables the electromechanical braking system and hub motor on each drive wheel to respond precisely. In addition, for the vehicle's anti-lock braking function, the hub motors mounted on each drive wheel feed back the internal wheel speed sensor signals to the hub motor control unit on each drive wheel via hard wiring. The hub motor control unit on each drive wheel inputs the wheel speed signal of its own wheel to the integrated drive and brake control unit via CAN communication. The integrated drive and brake control unit analyzes the wheel speed signals to determine whether the vehicle has a tendency to lock up. When a drive wheel is in a locked state, the integrated drive and brake control unit sends a signal to the hub motor control unit of that drive wheel to reduce the braking torque. The anti-lock function is achieved by controlling the target torque of the hub motor.

[0018] The main function of the integrated drive and braking control unit is to receive the autonomous driving and driver's driving intentions, calculate and output the target torques of the IWM and EMB of each drive wheel through internal algorithms. The integrated drive and braking control unit adopts a hierarchical control strategy architecture, which includes three modules: a human-machine co-driving coordination module, a longitudinal and lateral stability control module, and an electromechanical cooperative braking control module. The human-machine co-driving coordination module mainly receives the brake pedal push force F input by the driver. rod and steering wheel angle signal δ sw and the target deceleration signal a input to the autonomous driving system xaand the target front wheel steering angle signal δ fa This module identifies the driving intentions of both the driver and the autonomous driving system. Then, through driving consistency analysis and driving risk assessment, it formulates driving weight allocation rules for both the driver and the autonomous driving system. Finally, based on these rules, it calculates and outputs the comprehensive target deceleration 'a'. xd and the target front wheel steering angle δ fd The longitudinal and lateral stability control module analyzes the vehicle's current stability and formulates different control strategies based on different stability ranges. It calculates and outputs the total longitudinal braking force ΣF based on the input target deceleration and target front wheel steering angle. x Total demand yaw moment ΣM z The electromechanical coordinated braking control module comprehensively considers factors such as the working performance, working state, and working limits of each drive wheel EMB and IWM. Under the premise of ensuring braking efficiency, it aims to improve the braking energy recovery effect and maximize the braking potential of the wheel hub motors, calculating the target electromechanical braking torque T for each drive wheel EMB. EMBi IWM's target motor regenerative braking torque T R-IWMi IWM's target motor power consumption braking torque T C-IWMi It also outputs to the electromechanical brake control unit and hub motor control unit of each drive wheel.

[0019] To leverage the braking energy recovery advantages of the chassis distributed drive and braking system based on IWM and EMB and to maximize the braking potential of IWM, a cooperative braking control strategy is proposed. This function is located in the electromechanical cooperative braking control module of the control strategy architecture proposed in the second aspect. The electromechanical cooperative braking control strategy based on hub motor and EMB is as follows:

[0020] S1: First, receive the total required braking force and yaw moment signals input from the longitudinal and lateral stability control module;

[0021] S2: Calculate the required braking torque for each drive wheel;

[0022] S3: Calculate the maximum regenerative braking torque that can be provided by the hub motors of each drive wheel;

[0023] S4: Calculate the maximum power-consuming braking torque that can be provided by the hub motor of each drive wheel;

[0024] S5: Calculate the maximum mechanical braking torque that the EMB of each drive wheel can provide;

[0025] S6: Solve for the required target hub motor regenerative braking torque, target hub motor power consumption braking torque, and target EMB braking torque for each drive wheel;

[0026] S7: Output the target braking torque to the hub motor control unit and electromechanical brake control unit of each drive wheel respectively.

[0027] Taking the left front wheel as an example, step S6 is as follows:

[0028] S6a: When the battery SOC is greater than the threshold of 90% and the vehicle speed is greater than 5km / h, the motor can perform regenerative braking. When the maximum regenerative braking torque that the left front wheel hub motor can provide is greater than the braking torque required by the drive wheel, the regenerative braking torque of the target hub motor of the drive wheel is equal to the braking torque required by the drive wheel. The power consumption braking torque of the target hub motor and the target EMB braking torque are both 0.

[0029] S6b: When the required braking torque of the left front wheel is greater than the maximum regenerative braking torque that the hub motor of the drive wheel can provide, the regenerative braking torque of the target hub motor of the drive wheel is equal to the maximum regenerative braking torque that the hub motor of the drive wheel can provide, the target EMB braking torque of the drive wheel is equal to the required braking torque of the drive wheel minus the regenerative braking torque of the target hub motor of the drive wheel, and the power consumption braking torque of the target hub motor is 0.

[0030] S6c: When the battery SOC is greater than the threshold of 90% and the vehicle speed is greater than 5km / h, the motor cannot perform regenerative braking and will perform power consumption braking mode. When the maximum power consumption braking torque that the left front wheel hub motor can provide is greater than the braking torque required by the drive wheel, the power consumption braking torque of the target hub motor of the drive wheel is equal to the braking torque required by the drive wheel, and the regenerative braking torque of the target hub motor and the target EMB braking torque are both 0.

[0031] S6d: When the required braking torque of the left front wheel is greater than the maximum power-consuming braking torque that the hub motor of the drive wheel can provide, the power-consuming braking torque of the target hub motor of the drive wheel is equal to the maximum power-consuming braking torque that the hub motor of the drive wheel can provide. The target EMB braking torque of the drive wheel is equal to the required braking torque of the drive wheel minus the power-consuming braking torque of the target hub motor of the drive wheel. The regenerative braking torque of the target hub motor is 0.

[0032] During normal vehicle operation, the integrated drive and braking control unit is responsible for recognizing braking intentions and outputting control targets. These targets are then transmitted via CAN communication to the electromechanical braking control units of each drive wheel and the hub motor control unit, ultimately achieving coordinated braking control of the vehicle. When the integrated drive and braking control unit or CAN communication fails, the vehicle still needs to be able to stop smoothly in order to meet the safety requirements of intelligent driving vehicles.

[0033] When the integrated drive and braking control unit fails, the driver's and autonomous driving commands cannot be implemented, and the vehicle degrades to a fault-driven state. The electromechanical braking control units of each drive wheel use the brake pedal switch signal hard-wired input from the switch signal sensor, the left front wheel speed signal hard-wired input from the left front wheel speed sensor, the right front wheel speed signal hard-wired input from the right front wheel speed sensor, the left rear wheel speed signal hard-wired input from the left rear wheel speed sensor, and the right rear wheel speed signal hard-wired input from the right rear wheel speed sensor. At this time, the vehicle control objective is to bring the vehicle to a safe and smooth stop, and to ensure the vehicle's driving safety as much as possible.

[0034] The fault handling method for a distributed integrated drive and braking control system for intelligent driving provided by this invention includes the following steps:

[0035] The first step is that the electromechanical braking control unit installed on each drive wheel detects the signal of failure of the integrated drive and braking control unit and activates the fault driving function;

[0036] The second step is to determine whether the switch signal sensor indicates that the brake is depressed. If the switch signal sensor does not indicate that the brake is depressed, the electromechanical brake control unit on each drive wheel will not interfere with the vehicle's movement.

[0037] Third step: When the electromechanical brake control unit recognizes that the switch signal sensor signal is in the depressed state, it continues to determine whether each drive wheel is locked based on the wheel speed. If the drive wheel is not locked, the electromechanical brake control unit of each drive wheel sends segmented clamping commands to the electromechanical brake system of its respective drive wheel, setting the target clamping force of each wheel to 5000N in 0 to 1s, 10000N in 1 to 2s, 15000N in 2 to 3s, and 20000N in 3 to 4s.

[0038] Step 4: When a wheel locks up, the electromechanical brake control unit of the locked wheel activates the internal anti-lock braking control algorithm to adjust the wheel and achieve anti-lock braking control.

[0039] Step 5: When the first CAN communication module fails, the electromechanical braking control units on the left and right front drive wheels cannot receive the target electromechanical braking torque signal sent by the integrated drive and brake control unit. The hub motor control units on the left and right front drive wheels also cannot receive the target motor regenerative braking torque signal sent by the integrated drive and brake control unit. However, the electromechanical braking control units on the left and right rear drive wheels can still receive the target electromechanical braking torque signal sent by the integrated drive and brake control unit through the second CAN communication module. Similarly, the hub motor control units on the left and right rear drive wheels can still receive the target motor regenerative braking torque signal sent by the integrated drive and brake control unit through the second CAN communication module. At this time, when the driver presses the brake pedal, the rear axle of the vehicle still has normal service braking function. Simultaneously, the front axle receives the brake pedal switch signal via a hard-wired switch signal sensor, the left front wheel speed signal via a hard-wired wheel speed sensor, and the right front wheel speed signal via a hard-wired wheel speed sensor. The specific fault handling procedure for the first CAN communication module is as follows:

[0040] Step 1: The electromechanical brake control unit of the two front drive wheels detects the signal of failure of the first CAN communication module and activates the fault driving function;

[0041] Step 2: The electromechanical brake control unit of the two front drive wheels determines whether the switch signal sensor signal is depressed. If the switch signal sensor is not depressed, the electromechanical brake control unit of the two front drive wheels will not interfere with the vehicle's driving.

[0042] Step 3: When the two electromechanical brake control units on the front axle detect that the switch signal sensor is in the depressed state, they continue to determine whether the two wheels are locked based on their wheel speeds. If they are not locked, the electromechanical brake control units of the two drive wheels on the front axle send segmented clamping commands to the electromechanical brake systems of their respective drive wheels. The target clamping force of each drive wheel is set to 5000N in 0 to 1s, 10000N in 1 to 2s, 15000N in 2 to 3s, and 20000N in 3 to 4s.

[0043] Step 4: When a drive wheel on the current axle is locked, the anti-lock braking control algorithm inside the electromechanical brake control unit of that drive wheel enables the adjustment of the drive wheel to achieve anti-lock braking control.

[0044] When the rear axle drive wheels are locked, in order to ensure consistent control of the drive wheels, the integrated drive and brake control unit sets the internal anti-lock braking control algorithm enable signal to 0, and at the same time sets the internal anti-lock braking control algorithm enable signal of the electromechanical brake control unit to 1, thereby adjusting the rear axle drive wheels to achieve anti-lock braking control.

[0045] Step 6: When the second CAN communication module fails, the control of the front and rear axles is exactly the opposite of when the first CAN communication module fails. When both the first and second CAN communication modules fail, neither the front and rear axle electromechanical brake control unit nor the wheel hub motor control unit receives the target torque signal from the integrated drive and brake control unit. The control of the front and rear axle wheels is the same as when the integrated drive and brake control unit fails.

[0046] The beneficial effects of this invention are:

[0047] This invention provides a distributed integrated drive and braking control system and fault handling method for intelligent driving. Specifically, it proposes a distributed integrated drive and braking control system for the IWM+EMB chassis, which better leverages the advantages and performance potential of the IWM+EMB distributed chassis, meeting the requirements of intelligent driving and intelligent chassis technologies for "layout flexibility, architecture compatibility, and good control integration." For the key module of the proposed distributed integrated drive and braking control system—the integrated drive and braking control unit—this invention proposes a control strategy architecture for distributed integrated drive and braking control, providing valuable guidance for other researchers exploring the detailed control algorithms of this system. For the key strategy module of the proposed control strategy architecture—the electromechanical cooperative braking control module—this invention proposes a cooperative braking control strategy, which can maximize the braking energy recovery effect of the system and improve vehicle energy efficiency. Finally, this invention proposes a fault handling method for failures in the integrated drive and braking control unit or CAN communication, which can better meet the driving safety requirements of intelligent driving, achieve braking function backup, and ensure vehicle driving safety. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the distributed drive and braking integrated control system described in this invention.

[0049] Figure 2 This is a schematic diagram of the control strategy architecture of the integrated drive and braking control unit described in this invention.

[0050] Figure 3 This is a schematic diagram of the electromechanical coordinated braking control strategy described in this invention.

[0051] Figure 4 This is a schematic diagram of the failure handling method for the integrated drive and braking control unit described in this invention.

[0052] Figure 5 This is a schematic diagram of the fault handling method for the first CAN communication module of the front axle described in this invention.

[0053] The annotations in the image above are as follows:

[0054] 1. Hub motor; 2. Electromechanical braking system; 3. Brake pedal feel simulator

[0055] 4. Automatic driving system control unit; 5. Integrated drive and braking control unit.

[0056] 6. Power supply battery; 7. Drive wheel; 8. Wheel hub motor control unit.

[0057] 9. Electromechanical braking control unit; 10. Push rod force sensor; 11. First CAN communication module

[0058] 12. Second CAN communication module; 13. Wheel speed sensor; 14. Brake pedal device; 15. Push rod.

[0059] 16. Switch signal sensor 17. Gateway module. Detailed Implementation

[0060] Please see Figures 1 to 5 As shown:

[0061] The distributed integrated drive and braking control system for intelligent driving provided by this invention includes hub motors 1, electromechanical braking systems 2, brake pedal feel simulators 3, autonomous driving system control units 4, integrated drive and braking control units 5, and a power supply battery 6. Four hub motors 1 are provided, each mounted in the hub of one of the four drive wheels 7 of the vehicle body. Each hub motor 1 is connected to a hub motor control unit 8. Four electromechanical braking systems 2 are also provided, each mounted on the brake calipers of one of the four drive wheels 7 of the vehicle body. Each electromechanical braking system 2 is connected to an electromechanical braking control unit 9. A push rod 15 on the brake pedal feel simulator 3 is equipped with a push rod force sensor 10, which is connected to the integrated drive and braking control unit 5. The push rod force sensor 10 can transmit the collected data to the drive and brake integrated control unit 5 in real time. The autonomous driving system control unit 4 is connected to the drive and brake integrated control unit 5. The drive and brake integrated control unit 5 is also connected to the first CAN communication module 11 and the second CAN communication module 12. The first CAN communication module 11 is connected to the hub motor control unit 8 and the electromechanical brake control unit 9 mounted on the two drive wheels 7 at the front of the vehicle body, respectively. The second CAN communication module 12 is connected to the hub motor control unit 8 and the electromechanical brake control unit 9 mounted on the two drive wheels 7 at the rear of the vehicle body, respectively. The power supply battery 6 is connected to the aforementioned electromechanical brake control unit 9 and electromechanical brake system 2 and provides power to the electromechanical brake control unit 9 and electromechanical brake system 2.

[0062] Each of the four drive wheels 7 of the vehicle body is equipped with a wheel speed sensor 13. Each wheel speed sensor 13 is connected to the electromechanical brake control unit 9 mounted on the brake caliper of that wheel hub. The wheel speed sensor 13 can transmit the collected data to the electromechanical brake control unit 9 in real time.

[0063] A switch signal sensor 16 is installed at the connection between the brake pedal device 14 and the push rod 15 on the brake pedal feel simulator 3. The switch signal sensor 16 is connected to the electromechanical brake control unit 9 installed on the brake calipers of the four drive wheels 7 of the vehicle body. The switch signal sensor 16 can transmit the collected data to the electromechanical brake control unit 9 installed on the brake calipers of the four drive wheels 7 in real time, so that the electromechanical brake control unit 9 controls the operation of the electromechanical brake system 2. The switch signal sensor 16 is also connected to the drive-brake integrated control unit 5, and the switch signal sensor 16 can transmit the collected data to the drive-brake integrated control unit 5 in real time.

[0064] A gateway module 17 is installed on the connection line between the autonomous driving system control unit 4 and the integrated drive and braking control unit 5.

[0065] Two batteries are installed for power supply.

[0066] The aforementioned hub motor 1, electromechanical braking system 2, brake pedal feel simulator 3, automatic driving system control unit 4, integrated drive and brake control unit 5, power supply battery 6, hub motor control unit 8, electromechanical braking control unit 9, push rod force sensor 10, wheel speed sensor 13, switch signal sensor 16, and gateway module 17 are all assemblies of existing equipment; therefore, their specific models and specifications are not detailed.

[0067] The working principle of the distributed integrated drive and braking control system for intelligent driving provided by this invention is as follows:

[0068] The distributed integrated drive and braking control system for intelligent driving provided by this invention includes a brake pedal device 14 mechanically connected to a brake pedal feel simulator 3. The brake pedal device 14 is used for the driver to input braking intention, and the brake pedal feel simulator 3 is used to provide the driver with braking feel. A push rod force sensor 10 is installed between the two, which is used to collect the brake pedal push rod force to identify the driver's braking intention. Additionally, the brake pedal device 14 is also connected to a switch signal sensor 16, which is used to collect the brake pedal switch signal to identify whether the driver is braking. The push rod force sensor 10 and the switch signal sensor 16 can form a mutual backup. Furthermore, both the push rod force sensor 10 and the switch signal sensor 16 are hard-wired to the integrated drive and brake control unit 5. The main function of the integrated drive and brake control unit 5 is to analyze the signals from the push rod force sensor 10 and the switch signal sensor 16, and then identify the driver's driving intention through an algorithm. Then, it integrates the driving intention of the autonomous driving system input by the autonomous driving system control unit, and calculates and outputs the target braking torque of each drive wheel 7 IWM and EMB through an internal algorithm. In addition, the switch signal sensor 16 is also hard-wired to the electromechanical brake control units 9 mounted on the four drive wheels 7, so that these four wheel-end electromechanical brake control units 9 can receive the driver's driving intention. The driver's brake pedal switch signal is used for subsequent fault handling functions; the electromechanical brake control unit 9 mounted on each drive wheel 7 is hard-wired connected to the electromechanical brake system 2 on that drive wheel 7. The four electromechanical brake control units 9 convert the target electromechanical braking torque received from the drive-brake integrated control unit 5 into the target clamping force and control the connected electromechanical brake system 2 to respond. The four electromechanical brake systems 2 respectively feed back the Hall sensor signals of their respective internal systems to the connected electromechanical brake control units 9; the electromechanical brake control unit 9 mounted on each drive wheel 7 is also hard-wired connected to the wheel speed sensor 13 mounted on that drive wheel 7. It is used to receive wheel speed signals from wheel speed sensors 13 on the four drive wheels 7 for subsequent fault handling functions; in addition, the hub motors 1 mounted on the four drive wheels 7 are all connected to hub motor control units 8. The four hub motor control units 8 will control the hub motors 1 connected to them to respond to the target motor driving torque received from the integrated drive and brake control unit 5. The four hub motors 1 will feed back the wheel speed signals of the built-in wheel speed sensors to the hub motor control units 8 connected to them; the two power supply batteries 6 provide two power supply redundancies for the electromechanical braking system 2 on the four drive wheels 7. When any one power supply fails, the electromechanical braking system 2 can still perform normal braking.

[0069] From a communication perspective, the connection relationship and function of the above system are described. The autonomous driving system control unit 4 and the integrated drive and brake control unit 5 communicate through the gateway module 17. The autonomous driving system control unit 4 sends its braking intention-related signals to the gateway module 17 via Ethernet. The gateway module 17 converts them into CAN communication signals and sends them to the integrated drive and brake control unit 5. The integrated drive and brake control unit 5 is connected to the first CAN communication module 11 and the second CAN communication module 12 respectively. The integrated drive and brake control unit 5 supports two CAN communication channels. The integrated drive and brake control unit 5 sends electromechanical braking torque and electric motor braking torque to the electromechanical brake control unit 9 and the hub motor control unit 8 on the four drive wheels 7 respectively through the two CAN communication channels.

[0070] During normal operation, the autonomous driving system control unit 4 perceives the surrounding road and driving environment, determines the braking control intention signal for the vehicle, and inputs it to the integrated drive and brake control unit 5. Simultaneously, the driver, based on their own judgment of the road and environment, depresses the brake pedal. The push-rod force sensor 10 and the switch signal sensor 16 input the collected sensor signals to the integrated drive and brake control unit 5. The integrated drive and brake control unit 5 comprehensively processes the braking intentions of the autonomous driving system and the driver, and calculates the electromechanical braking torque and electric motor torque of each drive wheel 7 according to its internal algorithm. These are then output to the electromechanical braking control unit 9 and the wheel motor control unit 8 mounted on the four drive wheels 7, respectively. After receiving the signal, the unit 8 enables the electromechanical braking system 2 on each drive wheel 7 to respond precisely to the hub motor 1. In addition, for the vehicle's anti-lock braking function, the hub motor 1 mounted on each drive wheel 7 feeds back the internal wheel speed sensor signal to the hub motor control unit 8 on each drive wheel 7 via hard wiring. The hub motor control unit 8 on each drive wheel 7 inputs the wheel speed signal of its own wheel to the integrated drive and brake control unit 5 via CAN communication. The integrated drive and brake control unit 5 analyzes the wheel speed signal to determine whether the vehicle has a tendency to lock up. When a drive wheel 7 is in a locked state, the integrated drive and brake control unit 5 sends a signal to the hub motor control unit 8 of that drive wheel 7 to reduce the braking torque. The anti-lock function is achieved by controlling the target torque of the hub motor 1.

[0071] The main function of the integrated drive and braking control unit 5 is to receive the driving intentions of the autonomous driving system and the driver, calculate and output the target torques of each drive wheel (7IWM and EMB) through internal algorithms, and the integrated drive and braking control unit 5 adopts a hierarchical control strategy architecture, such as... Figure 2As shown, the control strategy architecture includes three modules: a human-machine co-driving coordination module, a longitudinal and lateral stability control module, and an electromechanical cooperative braking control module. The human-machine co-driving coordination module mainly receives the brake pedal push-rod force F input by the driver. rod and steering wheel angle signal δ sw and the target deceleration signal a input to the autonomous driving system xa and the target front wheel steering angle signal δ fa This module identifies the driving intentions of both the driver and the autonomous driving system. Then, through driving consistency analysis and driving risk assessment, it formulates driving weight allocation rules for both the driver and the autonomous driving system. Finally, based on these rules, it calculates and outputs the comprehensive target deceleration 'a'. xd and the target front wheel steering angle δ fd The longitudinal and lateral stability control module analyzes the vehicle's current stability and formulates different control strategies based on different stability ranges. It calculates and outputs the total longitudinal braking force ΣF based on the input target deceleration and target front wheel steering angle. x Total demand yaw moment ΣM z The electromechanical coordinated braking control module comprehensively considers factors such as the working performance, working state, and working limits of each drive wheel's EMB and IWM. Under the premise of ensuring braking efficiency, it aims to improve the braking energy recovery effect and maximize the braking potential of the wheel hub motors, calculating the target electromechanical braking torque T for each drive wheel's 7EMB. EMBi IWM's target motor regenerative braking torque T R-IWMi IWM's target motor power consumption braking torque T C-IWMi It also outputs to the electromechanical brake control unit 9 and the hub motor control unit 8 of each drive wheel 7.

[0072] To leverage the braking energy recovery advantages of the chassis distributed drive and braking system based on IWM and EMB and to maximize the braking potential of IWM, a cooperative braking control strategy is proposed. This function is located in the electromechanical cooperative braking control module of the control strategy architecture proposed in the second aspect, such as... Figure 3 The flow chart of the electromechanical cooperative braking control strategy based on hub motor 1 and EMB is shown below:

[0073] S1: First, receive the total required braking force and yaw moment signals input from the longitudinal and lateral stability control module;

[0074] S2: Calculate the required braking torque for each drive wheel 7;

[0075] S3: Calculate the maximum regenerative braking torque that can be provided by the hub motor 1 of each drive wheel 7;

[0076] S4: Calculate the maximum power-consuming braking torque that can be provided by the hub motor 1 of each drive wheel 7;

[0077] S5: Calculate the maximum mechanical braking torque that each drive wheel 7EMB can provide;

[0078] S6: Solve for the target hub motor regenerative braking torque, target hub motor power consumption braking torque, and target EMB braking torque required for each drive wheel 7;

[0079] S7: The target braking torque is output to the hub motor control unit 8 and electromechanical brake control unit 9 of each drive wheel 7.

[0080] Taking the left front wheel as an example, step S6 is as follows:

[0081] S6a: When the battery SOC is greater than the threshold of 90% and the vehicle speed is greater than 5km / h, the motor can perform regenerative braking. When the maximum regenerative braking torque that the hub motor 1 of the left front wheel can provide is greater than the braking torque required by the drive wheel 7, the regenerative braking torque of the target hub motor 1 of the drive wheel 7 is equal to the braking torque required by the drive wheel 7, and the power consumption braking torque of the target hub motor 1 and the target EMB braking torque are both 0.

[0082] S6b: When the required braking torque of the left front wheel is greater than the maximum regenerative braking torque that the hub motor 1 of the drive wheel 7 can provide, then the regenerative braking torque of the target hub motor 1 of the drive wheel 7 is equal to the maximum regenerative braking torque that the hub motor 1 of the drive wheel 7 can provide, the target EMB braking torque of the drive wheel 7 is equal to the required braking torque of the drive wheel 7 minus the regenerative braking torque of the target hub motor 1 of the drive wheel 7, and the power consumption braking torque of the target hub motor 1 is 0;

[0083] S6c: When the battery SOC is greater than the threshold of 90% and the vehicle speed is greater than 5km / h, the motor cannot perform regenerative braking and will perform power consumption braking mode. When the maximum power consumption braking torque that the left front wheel hub motor 1 can provide is greater than the braking torque required by the drive wheel 7, the power consumption braking torque of the target hub motor 1 of the drive wheel 7 is equal to the braking torque required by the drive wheel 7, and the regenerative braking torque of the target hub motor 1 and the target EMB braking torque are both 0.

[0084] S6d: When the required braking torque of the left front wheel is greater than the maximum power-consuming braking torque that the hub motor 1 of the drive wheel 7 can provide, then the power-consuming braking torque of the target hub motor 1 of the drive wheel 7 is equal to the maximum power-consuming braking torque that the hub motor 1 of the drive wheel 7 can provide. The target EMB braking torque of the drive wheel 7 is equal to the required braking torque of the drive wheel 7 minus the power-consuming braking torque of the target hub motor 1 of the drive wheel 7. The regenerative braking torque of the target hub motor 1 is 0.

[0085] During normal driving, the integrated drive and brake control unit 5 is responsible for recognizing braking intentions and outputting control targets. These targets are then sent to the electromechanical brake control units 9 and wheel hub motor control units 8 of each drive wheel 7 via CAN communication, ultimately achieving coordinated braking control of the vehicle. When the integrated drive and brake control unit 5 or the CAN communication fails, the vehicle still needs to be able to stop smoothly in order to meet the safety requirements of intelligent driving vehicles.

[0086] When the integrated drive and braking control unit 5 fails, the driver's and autonomous driving commands cannot be implemented, and the vehicle is downgraded to a fault driving state. The electromechanical braking control units 9 of each drive wheel 7 use the brake pedal switch signal hard-wired input from the switch signal sensor 16, the left front wheel speed signal hard-wired input from the left front wheel speed sensor 13, the right front wheel speed signal hard-wired input from the right front wheel speed sensor 13, the left rear wheel speed signal hard-wired input from the left rear wheel speed sensor 13, and the right rear wheel speed signal hard-wired input from the right rear wheel speed sensor 13. At this time, the vehicle control objective is to make the vehicle stop safely and smoothly, and to ensure the driving safety of the vehicle as much as possible.

[0087] The fault handling method for a distributed integrated drive and braking control system for intelligent driving provided by this invention includes the following steps:

[0088] The first step is that the electromechanical brake control unit 9 installed on each drive wheel 7 detects the signal of failure of the integrated drive and brake control unit 5 and activates the fault driving function;

[0089] The second step is to determine whether the signal of the switch signal sensor 16 is pressed. If the signal of the switch signal sensor 16 is not pressed, the electromechanical brake control unit 9 on each drive wheel 7 will not interfere with the vehicle's driving.

[0090] Third step: When the electromechanical brake control unit 9 recognizes that the signal from the switch signal sensor 16 is in the depressed state, it continues to determine whether each drive wheel 7 is in a locked state based on the wheel speed of each wheel. If the drive wheel 7 is not locked, the electromechanical brake control unit 9 of each drive wheel 7 sends a segmented clamping command to the electromechanical brake system 2 of its respective drive wheel 7, setting the target clamping force of each wheel to 5000N in 0 to 1s, 10000N in 1 to 2s, 15000N in 2 to 3s, and 20000N in 3 to 4s.

[0091] Step 4: When a wheel locks up, the electromechanical brake control unit 9 of the locked wheel activates the internal anti-lock braking control algorithm to adjust the wheel and achieve anti-lock braking control.

[0092] Step 5: When the first CAN communication module 11 fails, the electromechanical braking control units 9 on the left front drive wheel 7 and the right front drive wheel 7 cannot receive the target electromechanical braking torque signal sent by the integrated drive and brake control unit 5, and the hub motor control units 8 on the left front drive wheel 7 and the right front drive wheel 7 cannot receive the target motor regenerative braking torque signal sent by the integrated drive and brake control unit 5. At this time, the electromechanical braking control units 9 on the left rear drive wheel 7 and the right rear drive wheel 7 can still receive the target electromechanical braking torque signal sent by the integrated drive and brake control unit 5 through the second CAN communication module 12. The hub motor control units 8 on the rear drive wheel 7 and the right rear drive wheel 7 can still receive the target motor regenerative braking torque signal sent by the integrated drive and brake control unit 5 through the second CAN communication module 12. At this time, when the driver presses the brake pedal, the rear axle of the vehicle still has normal service braking function. At the same time, the front axle uses the brake pedal switch signal hard-wired input from the switch signal sensor 16, the left front wheel speed signal hard-wired input from the wheel speed sensor 13 on the left front drive wheel 7, and the right front wheel speed signal hard-wired input from the wheel speed sensor 13 on the right front drive wheel 7. The specific fault handling process of the first CAN communication module 11 is as follows:

[0093] Step 1: The electromechanical braking control unit 9 of the two front drive wheels 7 detects the signal of failure of the first CAN communication module 11 and activates the fault driving function;

[0094] Step 2: The electromechanical brake control unit 9 of the two front drive wheels 7 determines whether the signal of the switch signal sensor 16 is pressed. If the switch signal sensor 16 is not pressed, the electromechanical brake control unit 9 of the two front drive wheels 7 does not interfere with the vehicle's driving.

[0095] Step 3: The two electromechanical brake control units 9 of the front axle recognize that the switch signal sensor 16 is in the depressed state. They continue to determine whether the two wheels are locked based on their wheel speeds. If they are not locked, the electromechanical brake control units 9 of the two drive wheels 7 of the front axle send segmented clamping commands to the electromechanical brake system 2 of their respective drive wheels 7. The target clamping force of each drive wheel 7 is set to 5000N in 0 to 1s, 10000N in 1 to 2s, 15000N in 2 to 3s, and 20000N in 3 to 4s.

[0096] Step 4: When a certain drive wheel 7 on the current axis is locked, the anti-lock braking control algorithm inside the electromechanical brake control unit 9 of the drive wheel 7 enables the adjustment of the drive wheel 7 to achieve anti-lock braking control.

[0097] When the rear axle drive wheel 7 is locked, in order to ensure the consistency of drive wheel 7 control, the drive and brake integrated control unit 5 sets the internal anti-lock braking control algorithm enable signal to 0, and at the same time sets the internal anti-lock braking control algorithm enable signal of the electromechanical brake control unit 9 to 1, so as to adjust the drive wheel 7 of the rear axle to achieve anti-lock braking control.

[0098] Step 6: When the second CAN communication module 12 fails, the control of the front and rear axles is exactly the opposite of when the first CAN communication module 11 fails. When the first CAN communication module 11 and the second CAN communication module 12 fail at the same time, the front and rear axle electromechanical brake control unit 9 and the wheel hub motor control unit 8 will not receive the target torque signal from the integrated drive and brake control unit 5. The control of the front and rear axle wheels is the same as when the integrated drive and brake control unit 5 fails.

Claims

1. A distributed integrated drive and braking control system for intelligent driving, comprising hub motors, electromechanical braking systems, a brake pedal feel simulator, an autonomous driving system control unit, an integrated drive and braking control unit, and a power supply battery. Four hub motors are provided, each mounted in the hub of one of the four drive wheels of the vehicle body. Each hub motor is connected to a hub motor control unit. Four electromechanical braking systems are also provided, each mounted on the brake calipers of one of the four drive wheels of the vehicle body. Each electromechanical braking system is connected to an electromechanical braking control unit. A pushrod on the brake pedal feel simulator is equipped with a pushrod force sensor, which is connected to the integrated drive and braking control unit. The pushrod force sensor can transmit the collected data to the integrated drive and braking control unit in real time. The autonomous driving system control unit is connected to the integrated drive and braking control unit. The integrated drive and braking control unit is connected to a first CAN communication module and a second CAN communication module. The first CAN communication module is connected to the hub motor control unit and the electromechanical braking control unit mounted on the two front drive wheels of the vehicle body, respectively. The second CAN communication module is connected to the hub motor control unit and the electromechanical braking control unit mounted on the two rear drive wheels of the vehicle body, respectively. A power supply battery is connected to the aforementioned electromechanical braking control unit and electromechanical braking system, providing power to them. Wheel speed sensors are mounted on the four hubs of the four drive wheels of the vehicle body. Each wheel speed sensor is connected to the electromechanical braking control unit mounted on the brake caliper of that hub. The wheel speed sensors can transmit the collected data to the electromechanical braking control unit in real time. The characteristic feature is that: The brake pedal feel simulator is equipped with a switch signal sensor at the connection between the brake pedal device and the push rod. The switch signal sensor is connected to the electromechanical brake control unit mounted on the brake calipers of the four drive wheels of the vehicle body. The switch signal sensor can transmit the collected data to the electromechanical brake control unit mounted on the four drive wheel brake calipers in real time, so that the electromechanical brake control unit controls the operation of the electromechanical braking system. The switch signal sensor is also connected to the integrated drive and brake control unit, and the switch signal sensor can transmit the collected data to the integrated drive and brake control unit in real time.

2. The distributed integrated drive and braking control system for intelligent driving according to claim 1, characterized in that: A gateway module is installed on the connection line between the autonomous driving system control unit and the integrated drive and braking control unit.

3. A distributed integrated drive and braking control system for intelligent driving according to claim 1, characterized in that: The power supply battery consists of two units.

4. A fault handling method for a distributed drive and braking integrated control system for intelligent driving, characterized in that: The method includes the following steps: The first step is that the electromechanical braking control unit installed on each drive wheel detects the signal of failure of the integrated drive and braking control unit and activates the fault driving function; The second step is to determine whether the switch signal sensor indicates that the brake is depressed. If the switch signal sensor does not indicate that the brake is depressed, the electromechanical brake control unit on each drive wheel will not interfere with the vehicle's movement. Third step: When the electromechanical brake control unit recognizes that the switch signal sensor signal is in the depressed state, it continues to determine whether each drive wheel is locked based on the wheel speed. If the drive wheel is not locked, the electromechanical brake control unit of each drive wheel sends segmented clamping commands to the electromechanical brake system of its respective drive wheel, setting the target clamping force of each wheel to 5000N in 0 to 1s, 10000N in 1 to 2s, 15000N in 2 to 3s, and 20000N in 3 to 4s. Step 4: When a wheel locks up, the electromechanical brake control unit of the locked wheel activates the internal anti-lock braking control algorithm to adjust the wheel and achieve anti-lock braking control. Step 5: When the first CAN communication module fails, the electromechanical braking control units on the left and right front drive wheels cannot receive the target electromechanical braking torque signal sent by the integrated drive and brake control unit. The hub motor control units on the left and right front drive wheels also cannot receive the target motor regenerative braking torque signal sent by the integrated drive and brake control unit. However, the electromechanical braking control units on the left and right rear drive wheels can still receive the target electromechanical braking torque signal sent by the integrated drive and brake control unit through the second CAN communication module. Similarly, the hub motor control units on the left and right rear drive wheels can still receive the target motor regenerative braking torque signal sent by the integrated drive and brake control unit through the second CAN communication module. At this time, when the driver presses the brake pedal, the rear axle of the vehicle still has normal service braking function. Simultaneously, the front axle receives the brake pedal switch signal via a hard-wired switch signal sensor, the left front wheel speed signal via a hard-wired wheel speed sensor, and the right front wheel speed signal via a hard-wired wheel speed sensor. The specific fault handling procedure for the first CAN communication module is as follows: Step 1: The electromechanical brake control unit of the two front drive wheels detects the signal of failure of the first CAN communication module and activates the fault driving function; Step 2: The electromechanical brake control unit of the two front drive wheels determines whether the switch signal sensor signal is depressed. If the switch signal sensor is not depressed, the electromechanical brake control unit of the two front drive wheels will not interfere with the vehicle's driving. Step 3: When the two electromechanical brake control units on the front axle detect that the switch signal sensor is in the depressed state, they continue to determine whether the two wheels are locked based on their wheel speeds. If they are not locked, the electromechanical brake control units of the two drive wheels on the front axle send segmented clamping commands to the electromechanical brake systems of their respective drive wheels. The target clamping force of each drive wheel is set to 5000N in 0 to 1s, 10000N in 1 to 2s, 15000N in 2 to 3s, and 20000N in 3 to 4s. Step 4: When a drive wheel on the current axle is locked, the anti-lock braking control algorithm inside the electromechanical brake control unit of that drive wheel enables the adjustment of the drive wheel to achieve anti-lock braking control. When the rear axle drive wheels are locked, in order to ensure consistent control of the drive wheels, the integrated drive and brake control unit sets the internal anti-lock braking control algorithm enable signal to 0, and at the same time sets the internal anti-lock braking control algorithm enable signal of the electromechanical brake control unit to 1, thereby adjusting the rear axle drive wheels to achieve anti-lock braking control. Step 6: When the second CAN communication module fails, the control of the front and rear axles is exactly the opposite of when the first CAN communication module fails. When both the first and second CAN communication modules fail, neither the front and rear axle electromechanical brake control unit nor the wheel hub motor control unit receives the target torque signal from the integrated drive and brake control unit. The control of the front and rear axle wheels is the same as when the integrated drive and brake control unit fails.

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