A drive-by-wire chassis system based on vehicle-cloud cooperation and a control method thereof

Abstract

The application provides a drive-by-wire chassis system based on vehicle-cloud cooperation and a control method thereof, comprising a cloud controller, a vehicle-mounted controller, a trajectory planning controller, a drive-by-wire steering execution mechanism and a drive-by-wire braking execution mechanism; the application realizes precise cooperative control of each component of the drive-by-wire chassis based on vehicle-cloud cooperation, improves the maneuverability, driving stability and redundant safety of the vehicle, thereby improving the steering characteristics of the vehicle under all working conditions and widening the performance and safety boundaries of the vehicle. The cloud controller located in the remote server in the system receives information such as state parameters sent by the vehicle and information sent by other network-connected devices through wireless network communication, and after calculation by the cloud controller with a high-precision vehicle model in the remote server, active front and rear axle steering and coordinated control of four-wheel yaw moment of the vehicle drive-by-wire chassis can be realized, and the control output is sent to the vehicle-mounted controller, the output of the vehicle-mounted controller is switched, and optimal control and fault-tolerant control are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chassis control, and particularly relates to a drive-by-wire chassis system based on vehicle-cloud cooperation and a control method thereof. BACKGROUND

[0002] Under the two development trends of electrification and intelligentization, as the main carrier of intelligent driving, future high-level automatic driving will be realized based on a drive-by-wire chassis. The drive-by-wire chassis system cancels part of the heavy and low-precision pneumatic, hydraulic and mechanical connections, and replaces them with sensors, control units and electromagnetic actuators driven by electrical signals, so it has the advantages of compact structure, good controllability and fast response speed, but the safety of the system needs to be ensured. With the development of domain centralization of automotive electronics and electrical appliances, the chassis domain controller integrating multiple functions has emerged, but due to the limitation of the computing power of the vehicle-mounted controller, the collaborative work of each component of the drive-by-wire chassis cannot be realized, and the control advantages of the drive-by-wire chassis cannot be fully exerted.

[0003] At the same time, the cloud control system is a system that utilizes new generation information and communication technology, combines the advantages of networked control and cloud computing technology, and realizes precise control of the system in the cloud by combining advanced control methods. The cloud controller and the vehicle controller can perform fusion perception, collaborative decision-making and control, and comprehensively improve traffic efficiency and driving safety, which is also known as an "intelligent networked automobile cloud control system", and is the development trend of future intelligent driving. The invention patent with application number 202110183245.2 discloses a networked cloud control intelligent drive-by-wire chassis control system and a control method thereof, which performs real-time control on the vehicle drive-by-wire chassis based on the virtual digital twin model of the physical drive-by-wire chassis built in the cloud computing platform, and predicts the existing failure risk and fault, but does not involve collaborative control and fault tolerance of the cloud and vehicle controllers. The invention patent with authorized publication number CN112987574B discloses a control method of a cloud control intelligent chassis system based on multiple agents, which only continuously optimizes the control of the multi-agent coordination controller of the drive-by-wire chassis based on reinforcement learning, and does not involve collaborative optimal control of the vehicle controller and the cloud controller. Therefore, the application proposes a drive-by-wire chassis based on vehicle-cloud cooperation and a control method thereof, which realizes optimal control and fault-tolerant control of the vehicle drive-by-wire chassis by cooperation of the cloud and the vehicle. SUMMARY

[0004] In view of the above technical problems, the application provides a drive-by-wire chassis system based on vehicle-cloud cooperation and a control method thereof, which realizes precise collaborative control of each component of the drive-by-wire chassis based on vehicle-cloud cooperation, improves the maneuverability, driving stability and redundant safety of the vehicle, and thus improves the steering characteristics of the vehicle in all working conditions and widens the performance and safety boundaries of the vehicle.

[0005] The cloud controller located at the remote server in the system receives state parameters and other information sent by the vehicle and other network-connected devices through wireless network communication, and after calculation by the cloud controller with high-precision vehicle model in the remote server, active front and rear axle steering and coordinated control of four-wheel yaw moment of the vehicle drive-by-wire chassis can be realized, and the control output is sent to the vehicle-mounted controller to switch with the output of the vehicle-mounted controller to achieve optimal control and fault-tolerant control.

[0006] The application achieves the above technical purposes through the following technical means.

[0007] A drive-by-wire chassis system based on vehicle-cloud cooperation, comprising a cloud controller, a vehicle-mounted controller, a trajectory planning controller, a drive-by-wire steering execution mechanism and a drive-by-wire braking execution mechanism.

[0008] The cloud controller communicates with network-connected vehicles and network-connected roadside infrastructure respectively; the vehicle-mounted controller comprises a network transceiver, a chassis domain controller and a switching control module, the network transceiver is used for communicating with the cloud controller, sending vehicle position signal, vehicle heading angle, lateral and longitudinal vehicle speed and yaw rate state parameter information collected by sensors of the vehicle to the cloud, and receiving control signals transmitted back by the cloud; the chassis domain controller is used for active front axle and rear axle steering distribution, and yaw moment control in unstable state; the switching control module is connected with the cloud controller, the drive-by-wire steering execution mechanism and the drive-by-wire braking execution mechanism respectively; the trajectory planning controller is used for planning the expected path of the vehicle.

[0009] The network transceiver of the vehicle-mounted controller is used for receiving vehicle position signal, vehicle heading angle, vehicle speed and yaw rate state parameter information collected by sensors of the vehicle, and the expected path of the vehicle planned by the trajectory planning controller, and sending them to the cloud controller; the cloud controller is used for outputting target steering wheel angle control signal after receiving the state parameters and the expected path of the vehicle, the cloud controller combines the state information and the target steering wheel angle of the vehicle, decides the steering control signal and whether the yaw moment control is needed according to the vehicle state, and judges whether the limit is reached by comparing the real-time target steering wheel angle with the preset value, if the limit is reached, the active yaw moment control and four-wheel steering distribution are coordinated, and the control signal is transmitted to the switching control module of the vehicle-mounted controller; the switching control module is used for receiving control signals from the cloud controller and the chassis domain controller and calculating cost functions respectively, comparing the cost functions output by the cloud controller and the chassis domain controller, judging the control signal with smaller cost function as the optimal control signal, and controlling the drive-by-wire steering mechanism and the drive-by-wire braking mechanism of the vehicle.

[0010] In the scheme, the steer-by-wire steering actuator includes a front axle steering torque motor controller, a front axle steering torque motor, a clutch a, a front axle steering rack and pinion mechanism, a clutch b, a front axle steering angle motor, a front axle steering angle motor controller, a power supply, a rear axle steering motor controller, a rear axle steering motor, a clutch c, a rear axle steering rack and pinion mechanism, and a steering tie rod mechanism.

[0011] The front axle steering torque motor controller, the front axle steering angle motor controller, and the rear axle steering motor controller receive steering control signals from the switching control module. The front axle steering torque motor controller is connected to the front axle steering torque motor, the front axle steering angle motor controller is connected to the front axle steering angle motor, and the rear axle steering motor controller is connected to the rear axle steering motor. The front axle steering torque motor, the front axle steering angle motor, and the rear axle steering motor are respectively connected to the power supply. The front axle steering torque motor is connected to the front axle steering rack and pinion mechanism through the clutch a. The front axle steering angle motor is connected to the front axle steering rack and pinion mechanism through the clutch b. The rear axle steering motor is connected to the rear axle steering rack and pinion mechanism through the clutch c. The rear axle steering rack and pinion mechanism is connected to the steering tie rod mechanism.

[0012] In the scheme, the brake-by-wire brake actuator includes a brake motor controller and a brake motor.

[0013] The brake motor controller includes a brake motor controller a, a brake motor controller b, a brake motor controller c, and a brake motor controller d.

[0014] The brake motor includes a brake motor a, a brake motor b, a brake motor c, and a brake motor d.

[0015] The brake motor controller a is connected to the brake motor d, the brake motor controller b is connected to the brake motor a, the brake motor controller c is connected to the brake motor b, and the brake motor controller d is connected to the brake motor c.

[0016] The brake motor controller receives brake signals from the vehicle controller switching control module and drives the corresponding brake motor. The brake motor drives the brake hydraulic oil to brake the wheels. The four-wheel braking is independent of each other, and additional yaw moment control is achieved.

[0017] In the scheme, the cloud controller includes a vehicle model based on mechanism and data fusion and an integrated vehicle longitudinal and lateral dynamics controller, which is used for collaborative control of front axle and rear axle independent steering and four-wheel independent braking.

[0018] A control method of the steer-by-wire chassis system based on vehicle-cloud collaboration includes the following steps:

[0019] The network transceiver of the vehicle-mounted controller receives the vehicle heading angle, vehicle speed and yaw rate state parameter information collected by the vehicle sensor and the expected path of the vehicle planned by the trajectory planning controller, and sends them to the cloud controller;

[0020] After receiving the state parameters and the expected path of the vehicle, the cloud controller outputs a target steering wheel angle control signal for trajectory tracking control. The cloud controller combines the state information of the vehicle and the target steering wheel angle to decide the steering control signal and whether to perform yaw moment control. The cloud controller compares the real-time target steering wheel angle with the preset value to determine whether the limit is reached. If the limit is reached, the cloud controller coordinates active yaw moment control and four-wheel steering distribution, and transmits the control signal to the switching control module of the vehicle-mounted controller.

[0021] The switching control module receives the control signals from the cloud controller and the chassis domain controller, calculates the cost functions respectively, compares the cost functions output by the cloud controller and the chassis domain controller, judges the control signal with smaller cost function as the optimal control signal, and performs optimal collaborative control on the vehicle steer-by-wire mechanism and the vehicle brake-by-wire mechanism.

[0022] In the above scheme, the cloud controller predicts the vehicle position and stability index according to the reference trajectory output by the trajectory planning controller and the vehicle model, and outputs a control sequence U2 that minimizes the target function J2 in the prediction time domain N2; the target function J2 includes the sum of the predicted position error e d , the predicted heading angle error , the predicted yaw rate ω and the predicted center side slip angle β in the future N2 time domain; the vehicle-mounted controller outputs a control sequence U1 that minimizes the target function J1 in the prediction time domain N1; the target function J1 includes the sum of the predicted position error e d , the predicted heading angle error and the predicted yaw error e yaw in the future N1 time domain; the switching control module receives the first N p control signals of the control sequences output by the cloud controller and the vehicle-mounted controller, and calculates the cost functions Cost of the first N p control signals of the cloud controller and the vehicle-mounted controller respectively; the cost function Cost includes four parts, which are the predicted position error e d , the predicted heading angle error , the predicted yaw rate ω and the actuator stability

[0023] The target function of the vehicle-mounted controller:

[0024] Objective function of the cloud controller:

[0025] Controller output control variable: U = [δ f , δ r , F fl , F fr , F rl , F rr ] T

[0026] Controller output constraint: δ f ∈ [-δ fmax , δ fmax ]; δ r ∈ [-δ rmax , δ rmax ]; F ∈ [0, F max ]

[0027] Switching control module cost function of the on-board controller:

[0028] Wherein, Cost—cost function value, N1, N2, N p —prediction horizon, wherein the prediction horizon of the cloud controller is much larger than that of the on-board controller, α1—distance error coefficient, α2—heading angle error coefficient, α3—yaw angle error coefficient, γ1—yaw rate coefficient, γ2—center of mass side slip angle coefficient, e di —distance error in the i-th prediction horizon, —heading angle error in the i-th prediction horizon, e yawi —yaw angle error in the i-th prediction horizon, ω i —yaw rate in the i-th prediction horizon, β i —center of mass side slip angle in the i-th prediction horizon, δ f —front wheel steering angle control variable, δ r —rear wheel steering angle control variable, F fl , F fr , F rl , F rr —four-wheel braking force, δ fmax —maximum front wheel steering angle, δ rmax —maximum rear wheel steering angle, F max —maximum braking force, —actuator control signal rate of change;

[0029] The switching control module compares the cost functions of the cloud controller and chassis domain controller outputs, judges the control signal with the smaller cost function as the optimal control signal, performs optimal control output on the vehicle steer-by-wire mechanism and brake-by-wire mechanism, and controls the vehicle steer-by-wire mechanism and brake-by-wire mechanism.

[0030] In the above scheme, the optimal coordinated control of the vehicle's steer-by-wire mechanism and brake-by-wire mechanism by the on-board controller and the cloud controller specifically involves:

[0031] When the car is driving normally, the trajectory planning controller located in the vehicle plans a reference path according to driving needs and vehicle status, and sends the reference path or steering wheel input angle to the on-board controller and cloud controller for trajectory tracking and vehicle control.

[0032] The cloud controller and vehicle controller determine whether the vehicle speed is greater than a preset value V based on the connected roadside measurement equipment or vehicle speed sensor. lim If the preset value V is not reached lim Then determine whether the input steering angle is greater than the preset value δ. lim1 ;

[0033] If the preset value δ is not reached lim1 After calculation by the cloud controller, the control signals for the front and rear axle steering angles that minimize the objective function J2 are output, and the front and rear axles are under reverse steering control. After calculation by the vehicle controller, the control signals for the front and rear axle steering angles that minimize the objective function J1 are also output, and the front and rear axles are also under reverse steering control. After the two control signals are switched by the control module, the control signal with the smaller cost function Cost among the two controllers is output to the front axle steering torque motor controller, the front axle steering angle motor controller, and the rear axle steering motor controller, respectively, to drive the front axle steering torque motor, the front axle steering angle motor, and the rear axle steering motor to execute the steering control signal, thereby completing the active reverse steering of the front and rear axles. At the same time, the vehicle periodically feeds back the state parameters to the vehicle controller for trajectory planning and periodically outputs the reference trajectory signal, so that the controller updates the objective function and cost function and outputs a new optimal control signal again.

[0034] If the input steering angle is greater than the preset value δ lim1 If the vehicle is in U-turn mode, the cloud controller outputs front and rear axle reverse steering signals and torque control braking signals for the inner wheels that minimize the objective function J2, based on the reference trajectory and the vehicle's state. The on-board controller outputs front and rear axle reverse steering control signals that minimize the objective function J1. After switching the control module, the control signal with the smaller cost function among the two controllers is output to the front axle steering torque motor controller, front axle steering angle motor controller, rear axle steering motor controller, and brake motor controller to drive the front axle steering torque motor, front axle steering angle motor, rear axle steering motor, and braking mechanism. At the same time, the vehicle periodically feeds back its state parameters to the on-board controller for trajectory planning and periodically outputs reference trajectory signals, thereby updating the objective function and cost function and outputting new optimal control signals again.

[0035] If the vehicle speed is determined to be greater than the preset value V lim Then determine whether the expected heading angle or the input steering angle is greater than the preset value δ. lim2 Degree, δ lim2 Less than δ lim1 If the preset value δ is not reached lim2 The cloud controller and the vehicle controller output control signals that minimize the objective function for front and rear axle steering in the same direction. These signals are then switched by the control module, which outputs the control signal with the smaller cost function between the two controllers to the front axle steering torque motor controller, the front axle steering angle motor controller, and the rear axle steering motor controller, driving the front and rear axles to steer in the same direction. If the expected heading angle or input steering angle is greater than the preset value δ... lim1 If the vehicle is in an unstable state, the cloud controller outputs the front and rear axle steering signals with the minimum objective function and the differential braking signal for all four wheels. The vehicle controller outputs the front and rear axle steering control signals. After switching the control module, the control signal with the smaller cost function among the two controllers is output to the front axle steering torque motor controller, the front axle steering angle motor controller, the rear axle steering motor controller, and the brake motor controller to drive the front axle steering torque motor, the front axle steering angle motor, the rear axle steering motor, and the braking mechanism.

[0036] The above solution also includes fault-tolerant control steps for drive-by-wire chassis failures;

[0037] The fault-tolerant control of the drive-by-wire chassis includes controller failure modes; the controllers include three types: cloud controller failure, vehicle controller failure, and motor controller failure; when the cloud controller and vehicle controller are working normally, the switching control module performs normal switching control and controls all motor controllers; when the cloud controller fails, the switching control module directly outputs vehicle controller control commands to all motor controllers; when the vehicle controller fails, the switching control module outputs cloud controller control commands to achieve upper-level controller redundancy backup; when the lower-level motor controller fails, the mechanical connection of the motor controlled by the failed motor controller is cut off.

[0038] The above solution also includes sensor failure modes; the sensor failures include vehicle-mounted sensor failures and V2C vehicle-to-cloud communication failures; the vehicle-mounted sensor failures include angle sensor failures, vehicle speed sensor failures, and yaw rate sensor failures. When any of the above sensor failures occur, the cloud controller receives the vehicle status parameters detected by other connected vehicles and roadside equipment transmitted through the V2C network, calculates the parameters to replace the failed sensors, and sends them to the vehicle controller for redundant control; when V2C communication failure occurs, the vehicle-mounted sensors are still used to collect the vehicle status information.

[0039] The scheme further includes an actuator failure fault mode; the actuator failure includes a steering motor failure and a brake motor failure, wherein the steering motor failure includes a front axle steering torque motor failure, a front axle steering angle motor failure and a rear axle steering motor failure; in the front axle steering motor failure, when the front axle steering angle motor failure is detected, the clutch b is disconnected, the motor controller directly controls the front axle steering torque motor to follow the angle, and the front axle double motor coordination control is not performed; when the front axle steering torque motor failure is detected, the clutch a is disconnected, the motor controller directly controls the front axle steering angle motor to follow the angle, and the front axle double motor coordination control is not performed; when the front axle by-wire steering system fails as a whole, the clutch a and the clutch b are disconnected, and the motor controller controls the rear axle steering motor and the four-wheel brake motor to perform differential braking to maintain the vehicle stability control for a short time; when the rear axle steering motor failure is detected, the clutch c is disconnected, and the rear wheel active steering function is cancelled.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] The application provides a by-wire chassis system based on vehicle-cloud cooperation and a control method thereof, and precise cooperative control of each component of the by-wire chassis is realized based on vehicle-cloud cooperation, the maneuverability, driving stability and redundant safety of the vehicle are improved, and thus the steering characteristics of the vehicle under all working conditions are improved, and the performance and safety boundaries of the vehicle are widened.

[0042] The cloud controller used in the application has sufficient computing capacity, thereby improving real-time processing capacity and control precision, and realizing cooperative control of components of the by-wire chassis of the vehicle.

[0043] The vehicle model based on data driving and mechanism used in the cloud controller and updated in real time according to the vehicle state can reflect the running state of the vehicle in real time, and the control precision of the vehicle is improved.

[0044] The cloud controller and the vehicle-mounted controller are switched to control, so that the output control signal is always the optimal control signal, the safety redundancy of the controller is realized, and the control effect of the vehicle is improved.

[0045] The cloud controller can receive signals sent by other connected vehicles, the redundancy of the sensors of the vehicle can be realized, and the driving safety is improved.

[0046] The application adopts coordinated control of front axle and rear axle active by-wire steering and differential braking, so that the radius required in the low-speed large-angle steering process is shortened, and the maneuverability and the driving stability at high speed are improved.

[0047] The application uses a multi-motor actuator, so that the chassis system can effectively cope with the actuator failure problem and provide redundant protection.

[0048] Note that the description of these effects does not preclude the presence of other effects. One embodiment of the present application does not necessarily have all of the effects described above. The effects described above, effects in addition thereto, and the like will become apparent from the description of the specification, the attached drawings, the claims, and the like. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 Structure diagram of one embodiment of the present application;

[0050] Figure 2 Electronic control diagram of one embodiment of the present application;

[0051] Figure 3 Switching control diagram of one embodiment of the present application;

[0052] Figure 4 Fault mode diagram of one embodiment of the present application;

[0053] Figure 5 Control flowchart of one embodiment of the present application.

[0054] In the drawings, 1, brake motor controller a; 2, cloud controller; 3, on-vehicle controller; 4, front axle steering torque motor controller; 5, brake motor controller b; 6, brake motor a; 7, front axle steering torque motor; 8, clutch a; 9, front axle steering rack and pinion mechanism; 10, clutch b; 11, front axle steering angle motor; 12, brake motor b; 13, angle sensor; 14, brake motor controller c; 15, front axle steering angle motor controller; 16, power supply; 17, vehicle speed sensor; 18, yaw rate sensor; 19, rear axle steering motor controller; 20, brake motor controller d; 21, brake motor c; 22, rear axle steering motor; 23, clutch c; 24, rear axle steering rack and pinion mechanism; 25, tie rod mechanism; 26, brake motor d. DETAILED DESCRIPTION

[0055] Embodiments of the present application are described in detail below with reference to the accompanying drawings. In the drawings, like numbers refer to like elements throughout. The embodiments described below are exemplary and are intended to provide examples of the present application, and are not intended to limit the present application in any manner.

[0056] In the description of the present application, it needs to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "front", "back", "left", "right", "up", "down", "axial", "radial", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0057] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0058] Figure 1 The preferred embodiment of the cloud-based vehicle control chassis system is shown, which includes a cloud controller 2, a vehicle-mounted controller 3, a trajectory planning controller, a steer-by-wire steering execution mechanism and a brake-by-wire braking execution mechanism.

[0059] The cloud controller 2 communicates with the connected vehicle and the infrastructure of the connected roadside; the vehicle-mounted controller 3 includes a network transceiver, a chassis domain controller, a sensor and a switching control module, the network transceiver is used for communication with the cloud controller 2, sending the vehicle position signal, vehicle heading angle, transverse and longitudinal vehicle speed and yaw rate state parameter information collected by the vehicle sensor to the cloud, and receiving the control signal transmitted back by the cloud; the chassis domain controller is used for active front axle, rear axle steering distribution, and yaw moment control in unstable state; the switching control module is connected with the cloud controller 2, the steer-by-wire steering execution mechanism and the brake-by-wire braking execution mechanism; the trajectory planning controller is used for planning the expected path of the vehicle.

[0060] The network transceiver of the vehicle-mounted controller 3 is used to receive the vehicle position signal collected by the vehicle sensor, the vehicle heading angle, the vehicle speed and the yaw rate state parameter information, and the expected path of the vehicle planned by the trajectory planning controller, and send them to the cloud controller 2; the cloud controller 2 is used to receive the vehicle state parameters and the expected path, and then output the target steering wheel angle control signal for trajectory tracking control; the cloud controller 2 combines the state information of the vehicle and the target steering wheel angle, decides the steering control signal and whether the yaw moment control is needed according to the vehicle state, and judges whether the limit is reached according to the comparison between the real-time target steering wheel angle and the preset value, if the limit is reached, the active yaw moment control and four-wheel steering distribution are coordinated, and the control signal is transmitted to the switching control module of the vehicle-mounted controller 3; the switching control module is used to receive the control signals from the cloud controller 2 and the chassis domain controller and calculate the cost function respectively, compare the cost functions output by the cloud controller 2 and the chassis domain controller, judge the control signal with smaller cost function as the optimal control signal, and control the vehicle steer-by-wire mechanism and the brake-by-wire mechanism.

[0061] The cloud controller 2 is located in a remote server, communicates with the vehicle and other networked devices through a vehicle-mounted wireless network, can receive the state signals sent by the vehicle and other networked devices and complete calculation before sending the control signals back to the vehicle, is configured with a vehicle model based on mechanism and data fusion which is dynamically updated according to the vehicle state and has strong computing power, and can complete complex vehicle control task calculation.

[0062] The cloud controller 2 can realize real-time processing and control output of information; the cloud controller 2 reads information including vehicle speed, vehicle mass, tire parameters, road adhesion coefficient, etc. at certain time intervals, updates the vehicle model mathematical model based on mechanism and data fusion in the cloud controller 2; the cloud controller 2 integrates the vehicle chassis domain longitudinal and lateral dynamics control based on the vehicle mathematical model, which can realize the collaborative control of front and rear axle independent steering and four-wheel independent braking.

[0063] The vehicle-mounted controller 3 includes a network transceiver, a chassis domain controller, and a switching control module; the network transceiver is used for wireless communication with the cloud controller 2 at a fixed frequency, and can send the information collected by the vehicle to the cloud and receive the control signals transmitted back by the cloud; the chassis domain controller includes a linearized vehicle mathematical model, which can realize real-time control of the vehicle's linear control chassis, including control of active front and rear axle linear control steering and passive vehicle body stability control, and can realize active front and rear axle steering distribution and yaw moment control in an unstable state; the switching control module inputs control signals from the cloud controller 2 and the chassis domain controller of the vehicle-mounted controller 3 and calculates the corresponding cost function, and outputs the control signal with the smaller cost function; the cost function represents the pros and cons of the controller performance, which includes tracking error indicators, vehicle stability indicators, and actuator stability indicators, and the corresponding weight coefficients change under different vehicle speed conditions.

[0064] The linear control steering actuator includes a front axle steering torque motor controller 4, a front axle steering torque motor 7, a clutch a 8, a front axle steering gear rack mechanism 9, a clutch b 10, a front axle steering angle motor 11, a front axle steering angle motor controller 15, a power supply 16, a rear axle steering motor controller 19, a rear axle steering motor 22, a clutch c 23, a rear axle steering gear rack mechanism 24, and a steering tie rod mechanism 25; the front axle steering torque motor controller 4, the front axle steering angle motor controller 15, and the rear axle steering motor controller 19 receive steering control signals from the switching control module; the front axle steering torque motor controller 4 is connected with the front axle steering torque motor 7, the front axle steering angle motor controller 15 is connected with the front axle steering angle motor 11, and the rear axle steering motor controller 19 is connected with the rear axle steering motor 22; the front axle steering torque motor 7, the front axle steering angle motor 11, and the rear axle steering motor 22 are respectively connected with the power supply 16; the front axle steering torque motor 7 is connected with the front axle steering gear rack mechanism 9 through the clutch a 8, the front axle steering angle motor 11 is connected with the front axle steering gear rack mechanism 9 through the clutch b 10, and the rear axle steering motor 22 is connected with the rear axle steering gear rack mechanism 24 through the clutch c 23; the rear axle steering gear rack mechanism 24 is connected with the steering tie rod mechanism 25.

[0065] The steering torque motor controller 4, the steering angle motor controller 15 and the rear axle steering motor controller 19 receive the optimal steering control signal from the switching control module output, and drive the corresponding front axle steering torque motor 7, front axle steering angle motor 11 and rear axle steering motor 22 respectively; the front axle steering torque motor 7, front axle steering angle motor 11 and rear axle steering motor 22 are powered by the power supply 16, and are connected with the rack and pinion mechanism through the clutch a8, clutch b10 and clutch c23 respectively; when the clutch is closed, the power is successfully transmitted to the steering gear in the rack and pinion mechanism; when the clutch is disconnected, the power transmission is disconnected; the steering gear rack and pinion mechanism is connected with the steering tie rod mechanism, the steering gear rotates to drive the rack to move left and right, and the rack moves left and right to drive the steering tie rod mechanism to move, so as to realize the left and right steering of the wheels.

[0066] The brake-by-wire actuator includes a brake motor controller and a brake motor; the brake motor controller includes a brake motor controller a1, a brake motor controller b5, a brake motor controller c14 and a brake motor controller d20; the brake motor includes a brake motor a6, a brake motor b12, a brake motor c21 and a brake motor d26; the brake motor controller a1 is connected with the brake motor d26, the brake motor controller b5 is connected with the brake motor a6, the brake motor controller c14 is connected with the brake motor b12, and the brake motor controller d20 is connected with the brake motor c21; the brake motor controller receives the brake signal from the switching control module of the vehicle-mounted controller 3, and drives the corresponding brake motor; the brake motor drives the brake hydraulic oil to brake the wheels, and the four-wheel brake is independent, so as to realize the additional yaw moment control. Specifically, the brake motor a6, brake motor b12, brake motor c21 and brake motor d26 drive the left front, right front, right rear and left rear brake hydraulic circuits to brake respectively, so as to provide the vehicle with different directions of additional yaw moment, and the four brake circuits are independent.

[0067] In an embodiment of the present application, the cloud controller 2 contains a vehicle model based on mechanism and data fusion and an integrated vehicle longitudinal and lateral dynamics controller, which is used for the collaborative control of the independent front axle and rear axle steering and four-wheel independent braking.

[0068] In an embodiment of the present application, the cloud controller 2 and the vehicle-mounted controller 3 can independently control the drive-by-wire chassis of the vehicle, and the two controllers back up each other to achieve the controller redundancy effect.

[0069] In an embodiment of the present application, the cloud controller 2 can obtain the sensor parameters required by calculating the vehicle state information sent by other connected vehicles, and send the sensor parameters to the vehicle-mounted controller when the sensor of the vehicle fails, so as to achieve the sensor redundancy effect.

[0070] In one embodiment of the application, the cloud controller 2 can output the steering wheel angle according to the desired path when unmanned, and realize the optimal coordinated control of front and rear axle steering and four-wheel braking according to the input steering wheel angle when manned.

[0071] In one embodiment of the application, the steering actuator is divided into front axle steering and rear axle steering, wherein the front axle angle motor and the front axle torque motor are designed with different front axle double motor coordination coefficients under different working conditions according to the steering resistance torque variation characteristics under different speeds and angles.

[0072] The front axle double motor is to reduce the load of a single motor and increase the service life of the motor; the front axle angle motor and the front axle torque motor are the same in body, and the connection between the motor and the steering mechanism can be disconnected when one motor fails, so that the front axle steering can be driven by a single motor to realize the redundancy effect of the front axle steering motor.

[0073] The steer-by-wire steering mechanism can realize front axle steering and rear axle steering, wherein the front axle steering utilizes the front axle steering torque motor 7 and the front axle steering angle motor 11 to provide power through the clutch a8 and the clutch b10 to drive the gear in the front axle gear and rack mechanism 9 to rotate; the gear and the rack are meshed with each other to drive the rack to move left and right, thereby realizing the left and right steering of the wheels; the front axle steering is designed with different coordination coefficients of the front axle steering torque motor 7 and the front axle steering angle motor 11 under different working conditions with the target of stable angle motor load according to the steering resistance torque variation characteristics under different speeds and angles; the rear axle steering utilizes the rear axle steering motor 22 to provide power through the clutch c23 to drive the rear axle steering gear and rack mechanism 24 and the steering tie rod mechanism 25 to realize the left and right steering of the rear wheels; the front axle steering and the rear axle steering are independent of each other and act according to the control commands from the controller, thereby realizing the tracking of the target trajectory and the stability of the vehicle.

[0074] As Figure 2As shown, in one embodiment of the present application, the target vehicle collects the state parameters of the vehicle through the angle sensor 13, the vehicle speed sensor 17, the yaw rate sensor 18, etc.; the angle sensor 13 is used to collect the vehicle heading angle signal to determine the trajectory tracking error of the vehicle; the vehicle speed sensor 17 is used to collect the vehicle speed signal; and the yaw rate sensor 18 is used to collect the yaw rate signal. There is a trajectory planning controller on the target vehicle, which is used to plan the expected path of the vehicle; there is a network transceiver device on the target vehicle, which receives the collected state parameters and the planned expected path and sends them to the cloud controller; and there is a vehicle-mounted controller on the target vehicle, which directly receives the state parameters collected by the angle sensor 13, the vehicle speed sensor 17, the yaw rate sensor 18, etc. and the expected path of the trajectory planning module controller. After the cloud controller 2 receives the vehicle state parameters and the expected path transmitted through the network, it performs trajectory tracking control through the feedback control K containing feedforward control and outputs the target steering wheel angle control signal; there is an automatic driving lateral dynamics decision control module in the cloud controller, which has an integrated active four-wheel steering and active direct yaw moment control system, and after receiving the state information from the vehicle and the target steering wheel angle, it can decide the steering control signal and whether to perform yaw moment control according to the vehicle state; there are also an expected functional safety module and a coordinated integrated control module in the cloud controller, the yaw moment control is an expected functional safety SOTIF requirement considering the system performance, which realizes the advance coordination of active yaw moment control and four-wheel steering distribution in extreme working conditions, aims to quickly realize vehicle body stability control, reduces the steady-state expected yaw rate deviation, and improves the vehicle safety in extreme working conditions. The cloud controller finally transmits the control signal back to the switching control module located on the target vehicle. There is a chassis domain controller in the vehicle-mounted control, which contains an independent steering control system and a passive electronic vehicle body stability system, and can realize active four-wheel steering control of the vehicle and passive yaw moment control of the vehicle in unstable state according to the state information of the vehicle and the expected path. The chassis domain controller finally transmits the control signal to the switching control module and the control signal of the cloud controller for optimal control switching, and transmits the optimal control signal to the steering execution structure and the brake execution mechanism of the vehicle for execution, realizing the optimal control of the vehicle.

[0075] A control method according to the drive-by-wire chassis system based on vehicle-cloud cooperation, comprising the following steps:

[0076] The network transceiver device of the vehicle-mounted controller 3 receives the vehicle heading angle, vehicle speed and yaw rate state parameter information collected by the sensors of the vehicle and the expected path of the vehicle planned by the trajectory planning controller, and sends them to the cloud controller 2;

[0077] The cloud controller 2 receives the vehicle state parameters and the expected path, and then outputs a target steering wheel angle control signal for trajectory tracking control. The cloud controller 2 combines the state information of the vehicle and the target steering wheel angle, decides the steering control signal and whether the yaw moment control is needed according to the vehicle state, and judges whether the limit is reached according to the comparison between the real-time yaw moment and the preset value. If the limit is reached, the control coordination active yaw moment control and four-wheel steering distribution are performed, and the control signal is transmitted to the switching control module of the vehicle-mounted controller 3.

[0078] The switching control module receives the control signals from the cloud controller 2 and the chassis domain controller, and calculates the cost functions respectively. The cost functions output by the cloud controller 2 and the chassis domain controller are compared, and the control signal with the smaller cost function is judged as the optimal control signal. The vehicle-mounted controller 3 and the cloud controller 2 perform optimal collaborative control on the vehicle steer-by-wire mechanism and the vehicle brake-by-wire mechanism.

[0079] As shown in Figure 3 In an embodiment of the present application, the cloud controller 2 outputs a control sequence U2 that minimizes the target function J2 in a prediction time domain N2 according to the reference trajectory output by the trajectory planning controller and the high-precision vehicle model for accurate prediction of the vehicle position and stability indicators. The target function J2 includes the sum of the predicted position error e d , the predicted heading angle error , the predicted yaw rate ω and the predicted center side slip angle β in the future N2 time domain. The vehicle-mounted controller 3 outputs a control sequence U1 that minimizes the target function J1 in a prediction time domain N1. The target function J1 includes the sum of the predicted position error e d , the predicted heading angle error and the predicted yaw error e yaw Due to the limitation of computing power, the prediction time domain N2 of the cloud controller 2 is much larger than the prediction time domain N1 of the vehicle-mounted controller 3, so that more advanced prediction control can be achieved. The switching control module receives the first N P control signals of the control sequences output by the cloud controller 2 and the vehicle-mounted controller 3, and calculates the cost functions Cost of the first N P control signals of the cloud controller 2 and the vehicle-mounted controller 3 respectively. The cost function Cost includes four parts, which are the predicted position error e d , the predicted heading angle error , the predicted yaw rate ω and the actuator stability

[0080] The target function of the vehicle-mounted controller 3:

[0081] The target function of the cloud controller 2:

[0082] Controller output control variables: U = [δ f , δ r , F fl , F fr , F rl , F rr ] T

[0083] Controller output constraints: δ f ∈ [-δ fmax , δ fmax ]; δ r ∈ [-δ rmax , δ rmax ]; F ∈ [0, F max ]

[0084] Vehicle controller switching control module cost function:

[0085] wherein, Cost—cost function value, N1, N2, N p —prediction horizon, wherein the prediction horizon of the cloud controller is much larger than that of the vehicle controller, α1—distance error coefficient, α2—heading angle error coefficient, α3—yaw angle error coefficient, γ1—yaw rate coefficient, γ2—center of mass side slip angle coefficient, e di —distance error in the i prediction horizon, —heading angle error in the i prediction horizon, e yawi —yaw angle error in the i prediction horizon, ω i —yaw rate in the i prediction horizon, β i —center of mass side slip angle in the i prediction horizon, δ f —front wheel steering angle control variable, δ r —rear wheel steering angle control variable, F fl , F fr , F rl , F rr —four-wheel braking force, δ fmax —maximum front wheel steering angle, δ rmax —maximum rear wheel steering angle, F max —maximum braking force, —actuator control signal change rate;

[0086] The switching control module compares the cost functions output by the cloud controller 2 and the chassis domain controller, judges the control signal with smaller cost function as the optimal control signal, and performs optimal control output on the vehicle steer-by-wire mechanism and the brake-by-wire mechanism to control the vehicle steer-by-wire mechanism and the brake-by-wire mechanism, which are respectively executed by the corresponding front and rear axle steering mechanisms and brake-by-wire mechanisms.

[0087] The optimal collaborative control of the vehicle steer-by-wire mechanism and the brake-by-wire mechanism by the vehicle controller 3 and the cloud controller 2 is specifically:

[0088] When the vehicle is normally driving, the trajectory planning controller located in the vehicle plans a reference path according to the driving demand and the vehicle state, and sends the reference path or the steering wheel input angle to the vehicle controller 3 and the cloud controller 2 for trajectory tracking and vehicle control.

[0089] The cloud controller 2 and the vehicle controller 3 judge whether the vehicle speed is greater than a preset value V lim based on the networked roadside measurement equipment or the vehicle speed sensor 17. lim If the preset value V lim1 is not reached, it is judged whether the input steering angle is greater than a preset value δ lim1 .

[0090] If the preset value δ lim1 is not reached, the control signal of the front and rear axle steering angles with the minimum target function J2 output by the cloud controller 2 after calculation, and the front and rear axles are controlled in reverse steering; the control signal of the front and rear axle steering angles with the minimum target function J1 output by the vehicle controller 2 after calculation, and the front and rear axles are also controlled in reverse steering; the control signal with smaller cost function Cost from the two controllers is output to the front and rear axle steering motor controllers after the switching control module, and the front and rear axle steering motors are driven to execute the steering control signal, completing the active reverse steering of the front and rear axles, and the vehicle state parameters are periodically fed back to the vehicle controller 3 for trajectory planning and periodic output of the reference trajectory signal, so that the controller updates the target function and the cost function, and outputs new optimal control signals again.

[0091] If the input steering angle is greater than the preset value δ lim1If the vehicle is in U-turn mode, the cloud controller 2 outputs the front and rear axle reverse steering signals that minimize the objective function J2 and the torque control braking signal of the inner wheel, based on the reference trajectory and the vehicle's state. The vehicle controller 3 outputs the front and rear axle reverse steering control signal that minimizes the objective function J1. After switching the control module, the control signal with the smaller cost function among the two controllers is output to the front and rear axle steering motor controller and brake motor controller to drive the front and rear axle steering mechanism and braking mechanism. At the same time, the vehicle periodically feeds back the state parameters to the vehicle controller 3 for trajectory planning and periodically outputs the reference trajectory signal, thereby updating the objective function and cost function and outputting a new optimal control signal.

[0092] If the vehicle speed is determined to be greater than the preset value V lim Then determine whether the expected heading angle or the input steering angle is greater than the preset value δ. lim2 Degree, δ lim2 Less than δ lim1 If the preset value δ is not reached lim2 Then, the cloud controller 2 and the vehicle controller 3 output control signals that minimize the objective function for front and rear axle steering in the same direction. After switching the control module, the control signal with the smaller cost function among the two controllers is output to the front and rear axle steering motor controllers to drive the front and rear axles to steer in the same direction. If the expected heading angle or the input steering angle is greater than the preset value δ, lim1 If the vehicle is in an unstable state, the cloud controller 2 outputs the front and rear axle steering signals with the minimum objective function and the differential braking signal of the four wheels. The vehicle controller 3 outputs the front and rear axle steering control signals. After switching the control module, the control signal with the smaller cost function of the two controllers is output to the front and rear axle steering motor controller and the brake motor controller to drive the front and rear axle steering mechanism and braking mechanism.

[0093] like Figure 4 As shown, in one embodiment of the present invention, a fault-tolerant control step for the drive-by-wire chassis is further included; the fault-tolerant control for the drive-by-wire chassis includes three fault modes: controller failure, sensor failure, and actuator failure.

[0094] The controller failure refers to controller failure caused by hardware failure, software failure, communication failure, etc. The controller failure includes three types: cloud controller 2 failure, vehicle controller 3 failure, and motor controller failure. When cloud controller 2 and vehicle controller 3 are working normally, the switching control module performs normal switching control and controls all motor controllers. When cloud controller 2 fails, the switching control module directly outputs vehicle controller control commands to all motor controllers. When vehicle controller 3 fails, the switching control module outputs cloud controller control commands to achieve upper-level controller redundancy backup. When a lower-level motor controller fails, the mechanical connection of the motor controlled by the failed motor controller is severed.

[0095] The sensor failure refers to measurement failures caused by high-temperature aging, calibration errors, mechanical vibration, and communication failures. The sensor failures include vehicle-mounted sensor failures and V2C vehicle-to-cloud communication failures. The vehicle-mounted sensor failures include the failure of angle sensor 13, vehicle speed sensor 17, and yaw rate sensor 18. When the above-mentioned sensor failures occur, the cloud controller 2 receives the vehicle status parameters detected by other connected vehicles and roadside equipment through the V2C network to calculate the sensor parameters of the vehicle failure and sends them to the vehicle controller for redundant control. When V2C communication failure occurs, the vehicle-mounted sensors are still used to collect the vehicle status information.

[0096] The actuator failure refers to motor malfunctions caused by open circuits in components, unsoldered windings, or short circuits between turns. Actuator failures include steering motor failure and brake motor failure. Steering motor failure includes failure of the front axle steering torque motor (7), the front axle steering angle motor (11), and the rear axle steering motor (22). In the case of a front axle steering motor failure, when the front axle steering angle motor (11) is detected to be faulty, clutch b10 disengages, and the motor controller directly controls the front axle torque motor (7) for angle following, without coordinated control of the two front axle motors. When the front axle torque motor (7) is detected to be faulty, clutch a8 disengages, and the motor controller directly controls the front axle steering angle motor (11) for angle following, without coordinated control of the two front axle motors. When the entire front axle steering system fails, clutches a8 and b10 disengage, and the motor controller controls the rear axle steering motor (22) and the four-wheel brake motors to perform differential braking to maintain short-term vehicle stability. When the rear axle steering motor (22) is detected to be faulty, clutch c23 disengages, canceling the rear wheel active steering function.

[0097] like Figure 5 As shown, in one embodiment of the present invention, the specific flow of the control method for the vehicle-cloud collaborative drive-by-wire chassis system is as follows: When the vehicle is driving normally, the trajectory planning controller located in the vehicle plans a reference path according to driving needs and vehicle status, and sends the reference path or steering wheel input angle to the vehicle controller 3 and the cloud controller 2 for trajectory tracking and vehicle control. The cloud controller 2 and the vehicle controller 3 determine whether the vehicle speed is greater than 40km / h based on the connected roadside measurement equipment or the vehicle speed sensor 17; if it is less than 40km / h, they then determine whether the input steering angle is greater than 30 degrees.

[0098] If the input steering angle is greater than 30 degrees, it is determined that the vehicle is in a turning mode, at this time, the cloud controller 2 outputs the front and rear axle reverse steering signal and the torque control brake signal of the inner steering wheel according to the reference trajectory and the vehicle state, the vehicle controller 3 outputs the front and rear axle reverse steering control signal of the target function J1 minimum, and the switching control module outputs the control signal of the smaller cost function of the two controllers to the front and rear axle steering motor controller and brake motor controller to drive the brake mechanism; at the same time, the vehicle state parameters are fed back to the vehicle controller for trajectory planning, and the reference trajectory signal is periodically output, so that the controller updates the target function and the cost function, and outputs the new optimal control signal again.

[0099] If the input steering angle is greater than 30 degrees, it is determined that the vehicle is in a turning mode, at this time, the cloud controller 2 outputs the front and rear axle reverse steering signal and the torque control brake signal of the inner steering wheel according to the reference trajectory and the vehicle state, the vehicle controller 3 outputs the front and rear axle reverse steering control signal of the target function J1 minimum, and the switching control module outputs the control signal of the smaller cost function of the two controllers to the front and rear axle steering motor controller and brake motor controller to drive the brake mechanism; at the same time, the vehicle state parameters are fed back to the vehicle controller for trajectory planning, and the reference trajectory signal is periodically output, so that the controller updates the target function and the cost function, and outputs the new optimal control signal again.

[0100] If the vehicle speed is greater than 40km / h, it is determined whether the expected heading angle or the input steering angle is greater than 10 degrees; if it is not reached 10 degrees, the cloud controller 2 and the vehicle controller 3 output the front and rear axle same direction steering control signal of the target function minimum, and the switching control module outputs the control signal of the smaller cost function of the two controllers to drive the front and rear axle same direction steering, thereby improving the vehicle stability at medium and high speed; if it is determined that the expected heading angle or the input steering angle is greater than 10 degrees, it is determined that the vehicle is in an unstable mode, the cloud controller 2 outputs the front and rear axle same direction steering signal and the differential brake signal of the four wheels of the target function minimum, the vehicle controller 3 outputs the front and rear axle same direction steering control signal, and the switching control module outputs the control signal of the smaller cost function of the two controllers to the front and rear axle steering motor controller and brake motor controller to drive the brake motor controller, drive the front and rear axle steering mechanism and brake mechanism, thereby reducing the risk of vehicle instability. In addition, the error weight of the cost function under different vehicle speeds can be different, the trajectory tracking error weight is larger at low speed, and the stability index weight is larger at medium and high speed.

[0101] In order to realize optimal collaborative control and redundancy fault tolerance of the vehicle chassis-by-wire components, when the vehicle is running normally, the cloud controller 2 in the remote server communicates with the vehicle controller through the wireless network, can receive the sensor parameters sent by the vehicle sensor and the vehicle state parameters sent by other networked equipment, the cloud controller with strong computing power can make real-time decisions on different chassis-by-wire control commands according to the input expected path, steering wheel angle and vehicle speed, realize active front and rear axle chassis-by-wire steering angle distribution and direct yaw moment collaborative control of chassis-by-wire braking; At the same time, the vehicle controller 3 on the vehicle in running can also realize active front and rear axle chassis-by-wire steering and passive vehicle body stability control in unstable state. The actuator control commands output by the cloud controller 2 and the vehicle controller 3 enter the switching control module in the vehicle controller, and the optimal control signal with smaller cost function is sent to the actuator of the chassis-by-wire, including the front and rear axle steering mechanism and the four-wheel braking mechanism, the actuator executes the action, so that the vehicle realizes tracking the target path and keeping the vehicle stable, and realizes the purpose of improving the maneuverability of the vehicle at low speed and the stability at medium and high speed. In addition, considering the redundancy safety requirement of the system, the cloud controller and the vehicle controller are independent of each other. When one of the cloud controller 2 and the vehicle controller 3 fails, it will not affect the normal work of the other controller, so as to achieve the redundancy purpose of the controller; When the vehicle sensor fails, the state information of the vehicle sent by other networked vehicles and roadside networked infrastructure can be obtained through the cloud controller 2, so as to replace the vehicle state signal collected by the sensor and realize vehicle control, so as to achieve the redundancy purpose of the sensor; When the steering actuator fails, the front and rear axle steering and the front axle double motor system structure can realize the normal running of the vehicle, and ensure the driving safety. It aims to solve the problems that the vehicle controller cannot realize complex chassis coordination control strategy calculation and fault tolerance.

[0102] It should be understood that although the present specification is described in terms of various embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be combined appropriately to form other embodiments that those skilled in the art can understand.

[0103] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present application, and are not used to limit the protection scope of the present application, and any equivalent embodiments or changes made without departing from the spirit of the present application should be included in the protection scope of the present application.

Claims

1. A drive-by-wire chassis system based on vehicle-cloud cooperation, characterized in that, The cloud controller (2), the vehicle controller (3), the trajectory planning controller, the steer-by-wire steering actuator and the brake-by-wire braking actuator are included. The cloud controller (2) communicates with the connected vehicle and the infrastructure of the connected roadside respectively; the vehicle controller (3) includes a network transceiver, a chassis domain controller and a switching control module, the network transceiver is used for communicating with the cloud controller (2), sending the vehicle position signal, the vehicle heading angle, the lateral and longitudinal vehicle speed and the yaw rate state parameter information collected by the sensors of the vehicle to the cloud, and receiving the control signal transmitted back by the cloud; the chassis domain controller is used for the active front axle, rear axle steering distribution, and the yaw moment control in the unstable state; the switching control module is connected with the cloud controller (2) and the steer-by-wire steering actuator and the brake-by-wire braking actuator respectively; the trajectory planning controller is used for planning the expected path of the vehicle; The network transceiver of the vehicle controller (3) is used for receiving the vehicle position signal, the vehicle heading angle, the vehicle speed and the yaw rate state parameter information collected by the sensors of the vehicle and the expected path of the vehicle planned by the trajectory planning controller, and sending them to the cloud controller (2); the cloud controller (2) is used for receiving the vehicle state parameters and the expected path, and then outputting the target steering wheel angle control signal for trajectory tracking control, the cloud controller (2) combines the state information of the vehicle and the target steering wheel angle, decides the steering control signal and whether the yaw moment control is needed according to the vehicle state, and judges whether the limit is reached by comparing the real-time target steering wheel angle with the preset value, if the limit is reached, the active yaw moment control and four-wheel steering distribution are coordinated, and the control signal is transmitted to the switching control module of the vehicle controller (3); the switching control module is used for receiving the control signals from the cloud controller (2) and the chassis domain controller and calculating the cost functions respectively, comparing the cost functions output by the cloud controller (2) and the chassis domain controller, judging the control signal with smaller cost function as the optimal control signal, and controlling the steer-by-wire steering mechanism and the brake-by-wire braking mechanism; The cloud controller (2) and the vehicle-mounted controller (3) judge whether the vehicle speed is greater than a preset value V according to the networked roadside measurement equipment or the vehicle speed sensor (17) lim If the preset value V is not reached lim , it is further judged whether the input steering angle is greater than a preset value δ lim1 ; If the preset value δ is not reached lim1 The cloud controller (2) calculates the minimum target function J2 and outputs the control signal of the front and rear axle steering angle. At this time, the front and rear axle is a reverse steering control. The vehicle-mounted controller (3) calculates the minimum target function J1 and outputs the control signal of the front and rear axle steering angle. The front and rear axle is also a reverse steering control signal. The two control signals are output through the switching control module to output the control signal with the smallest cost function Cost in the two controllers. If the vehicle speed is determined to be greater than the preset value V lim Then determine whether the expected heading angle or the input steering angle is greater than the preset value δ. lim2 Degree, δ lim2 Less than δ lim1 If the preset value δ is not reached lim2 Then, the cloud controller (2) and the vehicle controller (3) output control signals for front and rear axles to steer in the same direction with the minimum objective function. After switching the control module, the control signal with the smaller cost function among the two controllers is output to the front axle steering torque motor controller (4), the front axle steering angle motor controller (15), and the rear axle steering motor controller (19) to drive the front and rear axles to steer in the same direction. If the expected heading angle or the input steering angle is greater than the preset value δ, lim1 If the vehicle is in an unstable state, the cloud controller (2) outputs the front and rear axle steering signals with the minimum objective function and the differential braking signals of the four wheels, and the vehicle controller (3) outputs the front and rear axle steering control signals with the same direction.

2. The drive-by-wire chassis system based on vehicle-cloud collaboration according to claim 1, characterized in that, The steer-by-wire steering actuator includes a front axle steering torque motor controller (4), a front axle steering torque motor (7), a clutch a (8), a front axle steering gear rack mechanism (9), a clutch b (10), a front axle steering angle motor (11), a front axle steering angle motor controller (15), a power supply (16), a rear axle steering motor controller (19), a rear axle steering motor (22), a clutch c (23), a rear axle steering gear rack mechanism (24), a steering tie rod mechanism (25). The front axle steering torque motor controller (4), the front axle steering angle motor controller (15), and the rear axle steering motor controller (19) receive the steering control signal from the switching control module, the front axle steering torque motor controller (4) is connected with the front axle steering torque motor (7), the front axle steering angle motor controller (15) is connected with the front axle steering angle motor (11), and the rear axle steering motor controller (19) is connected with the rear axle steering motor (22); the front axle steering torque motor (7), the front axle steering angle motor (11), and the rear axle steering motor (22) are respectively connected with the power supply (16), the front axle steering torque motor (7) is connected with the front axle steering rack and pinion mechanism (9) through the clutch a (8), the front axle steering angle motor (11) is connected with the front axle steering rack and pinion mechanism (9) through the clutch b (10), and the rear axle steering motor (22) is connected with the rear axle steering rack and pinion mechanism (24) through the clutch c (23); the rear axle steering rack and pinion mechanism (24) is connected with the tie rod mechanism (25).

3. The cloud-vehicle collaborative-based drive-by-wire chassis system according to claim 1, wherein, The brake-by-wire actuator comprises a brake motor controller and a brake motor; The brake motor controller comprises a brake motor controller a (1), a brake motor controller b (5), a brake motor controller c (14), and a brake motor controller d (20); The brake motor comprises a brake motor a (6), a brake motor b (12), a brake motor c (21), and a brake motor d (26); The brake motor controller a (1) is connected with the brake motor d (26), the brake motor controller b (5) is connected with the brake motor a (6), the brake motor controller c (14) is connected with the brake motor b (12), and the brake motor controller d (20) is connected with the brake motor c (21); The brake motor controller receives the brake signal from the switching control module of the vehicle-mounted controller (3) and drives the corresponding brake motor; the brake motor drives the brake hydraulic oil to brake the wheels, and the four-wheel brakes are independent of each other, thereby realizing the additional yaw moment control.

4. The cloud-in-vehicle cooperation based drive-by-wire chassis system according to claim 1, characterized in that, The cloud controller (2) comprises a vehicle model based on mechanism and data fusion and an integrated vehicle longitudinal and lateral dynamics controller, which are used for the cooperative control of the front axle and rear axle independent steering and four-wheel independent braking.

5. The control method of the drive-by-wire chassis system based on vehicle cloud cooperation according to claim 4, characterized in that, The steps comprise: The network transceiver of the vehicle-mounted controller (3) receives the vehicle heading angle, vehicle speed, and yaw rate state parameter information collected by the vehicle sensor and the expected path planned by the trajectory planning controller, and sends them to the cloud controller (2); The cloud controller (2) receives the vehicle state parameters and the expected path, and outputs a target steering wheel angle control signal for trajectory tracking control. The cloud controller (2) combines the state information of the vehicle and the target steering wheel angle, decides the steering control signal and whether the yaw moment control is needed according to the vehicle state, and judges whether the limit is reached by comparing the real-time target steering wheel angle with the preset value. If the limit is reached, the active yaw moment control and four-wheel steering distribution are coordinated, and the control signal is transmitted to the switching control module of the vehicle-mounted controller (3). The switching control module receives the control signals from the cloud controller (2) and the chassis domain controller, calculates the cost functions respectively, compares the cost functions output by the cloud controller (2) and the chassis domain controller, judges the control signal with smaller cost function as the optimal control signal, and the vehicle-mounted controller (3) and the cloud controller (2) perform optimal collaborative control on the vehicle steer-by-wire mechanism and the vehicle brake-by-wire mechanism.

6. The control method of the drive-by-wire chassis system based on vehicle cloud cooperation according to claim 5, characterized in that, The cloud controller (2) predicts the vehicle position and stability index according to the reference trajectory output by the trajectory planning controller and the vehicle model, and outputs the control sequence U2 that minimizes the objective function J2 in the prediction time domain N2; the objective function J2 includes the sum of the predicted position error , the predicted heading angle error , the predicted yaw rate , and the predicted side slip angle in the future N2 time domain; the on-board controller (3) outputs the control sequence U1 that minimizes the objective function J1 in the prediction time domain N1; the objective function J1 includes the sum of the predicted position error , the predicted heading angle error , and the predicted yaw error in the future N1 time domain; the switching control module receives the first N p control signals from the control sequences output by the cloud controller (2) and the on-board controller (3), and respectively calculates the cost function Cost for the first N p control signals of the cloud controller (2) and the on-board controller (3); the cost function Cost includes four parts, which are the predicted position error , the predicted heading angle error , the predicted yaw rate , and the actuator stability ​ The objective function of the vehicle-mounted controller (3): ; The objective function of the cloud controller (2): ; Controller output control quantity: ; Controller output constraints: ; Vehicle controller switching control module cost function: ; wherein, a cost function value, a prediction horizon, wherein the cloud controller prediction horizon is much larger than the on-board controller prediction horizon, a distance error coefficient, a heading angle error coefficient, a yaw angle error coefficient, a yaw rate coefficient, a center of mass side slip angle coefficient, a first distance error of the prediction horizon, a first heading angle error of the prediction horizon, a first yaw angle error of the prediction horizon, a first yaw rate of the prediction horizon, a first center of mass side slip angle of the prediction horizon, a front wheel steering angle control amount, a rear wheel steering angle control amount, a four-wheel braking force, a front wheel steering angle maximum value, a rear wheel steering angle maximum value, a braking force maximum value, an actuator control signal change rate; The switching control module compares the cost functions output by the cloud controller (2) and the chassis domain controller, judges the control signal with smaller cost function as the optimal control signal, and performs optimal control output on the vehicle steer-by-wire mechanism and the vehicle brake-by-wire mechanism.

7. The control method of the drive-by-wire chassis system based on vehicle cloud cooperation according to claim 6, characterized in that, The optimal collaborative control of the vehicle-mounted controller (3) and the cloud controller (2) on the vehicle steer-by-wire mechanism and the vehicle brake-by-wire mechanism is as follows: When the vehicle is normally driven, the trajectory planning controller located in the vehicle plans a reference path according to the driving demand and the vehicle state, and sends the reference path or the steering wheel input angle to the vehicle-mounted controller (3) and the cloud controller (2) for trajectory tracking and vehicle control. The cloud controller (2) and the vehicle-mounted controller (3) judge whether the vehicle speed is greater than a preset value V according to the networked roadside measurement equipment or the vehicle speed sensor (17) lim If the preset value V is not reached lim , it is further judged whether the input steering angle is greater than a preset value δ lim1 ; If the preset value δ is not reached lim1 , the cloud controller (2) calculates the output of the target function J2 minimum front and rear axle angle control signal, this time the front and rear axle for reverse steering control; through the vehicle controller (3) after the calculation output of the target function J1 minimum front and rear axle angle control signal, the front and rear axle is also a reverse steering control signal; two control signal after the switching control module output two controller cost function Cost small control signal to the front axle steering torque motor controller (4), front axle steering angle motor controller (15), rear axle steering motor controller (19), respectively drive front axle steering torque motor (7), front axle steering angle motor (11), rear axle steering motor (22) to execute steering control signal, complete the front and rear axle active reverse steering, at the same time the state parameters of the vehicle are fed back to the vehicle controller (3) for trajectory planning, and the reference trajectory signal is periodically output, so that the controller updates the target function and the cost function, and the new optimal control signal is output again; If the input steering angle is greater than the preset value δ lim1 , it is determined that the vehicle is in the turning mode at this time. At this time, the cloud controller (2) outputs the front and rear axle reverse steering signals and the steering inner wheel torque control brake signal with the minimum target function J2 according to the reference trajectory and the vehicle state, the vehicle-mounted controller (3) outputs the front and rear axle reverse steering control signal with the minimum target function J1, and the control signal with the smaller cost function of the two controllers is output to the front axle steering torque motor controller (4), the front axle steering angle motor controller (15), the rear axle steering motor controller (19), and the brake motor controller through the switching control module, to drive the front axle steering torque motor (7), the front axle steering angle motor (11), the rear axle steering motor (22), and the brake mechanism. At the same time, the vehicle state parameters are periodically fed back to the vehicle-mounted controller (3) for trajectory planning, and the reference trajectory signal is periodically output, so that the controller updates the target function and the cost function, and outputs new optimal control signals again. If the vehicle speed is determined to be greater than the preset value V lim Then determine whether the expected heading angle or the input steering angle is greater than the preset value δ. lim2 Degree, δ lim2 Less than δ lim1 If the preset value δ is not reached lim2 Then, the cloud controller (2) and the vehicle controller (3) output control signals for front and rear axles to steer in the same direction with the minimum objective function. After switching the control module, the control signal with the smaller cost function among the two controllers is output to the front axle steering torque motor controller (4), the front axle steering angle motor controller (15), and the rear axle steering motor controller (19) to drive the front and rear axles to steer in the same direction. If the expected heading angle or the input steering angle is greater than the preset value δ, lim1 If the vehicle is in an unstable state, the cloud controller (2) outputs the front and rear axle steering signals with the minimum objective function and the differential braking signals of the four wheels. The vehicle controller (3) outputs the front and rear axle steering control signals. After switching the control module, the control signal with the smaller cost function among the two controllers is output to the front axle steering torque motor controller (4), the front axle steering angle motor controller (15), the rear axle steering motor controller (19) and the brake motor controller to drive the front axle steering torque motor (7), the front axle steering angle motor (11), the rear axle steering motor (22) and the braking mechanism.

8. The control method of the drive-by-wire chassis system based on vehicle cloud cooperation according to claim 5, characterized in that, It also includes a line control chassis fault tolerance control step. The line control chassis fault tolerance control includes a controller failure fault mode; the controller includes three types of cloud controller (2) failure, vehicle-mounted controller (3) failure and motor controller failure; when the cloud controller (2) and the vehicle-mounted controller (3) are working normally, the switching control module normally performs switching control and controls all motor controllers; when the cloud controller (2) fails, the switching control module directly outputs the vehicle-mounted controller control command to all motor controllers; when the vehicle-mounted controller (3) fails, the switching control module outputs the cloud controller control command, realizing the upper controller redundancy backup; when the lower motor controller fails, the mechanical connection of the motor controlled by the failed motor controller is cut off.

9. The control method of the drive-by-wire chassis system based on vehicle cloud cooperation according to claim 8, characterized in that, Also include sensor failure failure mode; the sensor failure includes vehicle-mounted sensor failure and V2C vehicle cloud communication failure; the vehicle-mounted sensor failure includes angle sensor (13) failure, vehicle speed sensor (17) failure, yaw rate sensor (18) failure, when the above-mentioned sensor failure occurs, the cloud controller (2) receives the other networked vehicles and road side equipment detected vehicle state parameters transmitted through the V2C network to calculate the vehicle failure sensor and send to the vehicle-mounted controller for redundant control; When V2C communication failure occurs, the vehicle-mounted sensor is still used to collect the vehicle state information.

10. The control method of the drive-by-wire chassis system based on vehicle cloud cooperation according to claim 8, characterized in that, Also include actuator failure failure mode; the actuator failure includes steering motor failure and brake motor failure, wherein the steering motor failure includes front axle steering torque motor (7) failure, front axle steering angle motor (11) failure, rear axle steering motor (22) failure; In the front axle steering motor failure, when the front axle steering angle motor (11) failure is detected, the clutch b (10) is disconnected, the motor controller directly controls the front axle steering torque motor (7) to follow the angle, and the front axle double motor coordination control is not performed; When the front axle steering torque motor (7) failure is detected, the clutch a (8) is disconnected, the motor controller directly controls the front axle steering angle motor (11) to follow the angle, and the front axle double motor coordination control is not performed; When the front axle by-wire steering system fails as a whole, the clutch a (8), the clutch b (10) are disconnected, and the motor controller controls the rear axle steering motor (22) and the four-wheel brake motor to differential brake to keep the vehicle stable control for a short time; When the rear axle steering motor (22) failure is detected, the clutch c (23) is disconnected, and the rear wheel active steering function is cancelled.

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