A kind of by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its power chassis domain integrated control architecture

Abstract

The application discloses a kind of drive-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its power chassis domain integrated control architecture, including driving simulation system, electric drive system, drive-by-wire brake system, drive-by-wire steering system, active suspension system, power chassis domain integrated control system, vehicle real-time simulation system, test bench measurement and control system.Power chassis domain integrated control system receives driver instruction, road environment and vehicle model information and power chassis each execution system and its load simulation device response information, completes decision instruction.By using hierarchical control architecture, power chassis domain integrated control system includes vehicle motion stability judgment layer, vehicle motion integrated control layer and actuator and its load control layer.The application is used for drive-by-wire chassis intelligent electric vehicle horizontal and vertical, horizontal and vertical, horizontal and vertical and other various motion mode control algorithm test and verification, with drive-by-wire chassis function complete, power chassis domain high degree of integration, test coverage wide and other characteristics.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicle hardware-in-the-loop test bench, in particular to a kind of line control chassis electric vehicle hardware-in-the-loop simulation test bench and its power chassis domain integrated control architecture. BACKGROUND

[0002] With the accelerated fusion development of the "new four technologies" of automobile, the research and development of intelligent driving function of electric vehicle is also continuously deepening, and power transmission and chassis as the carrier and execution component of intelligent driving function implementation, the verification of its function and control strategy is crucial to ensure the safety, reliability and comfort of vehicle. At the same time, with the continuous evolution of automobile electronic and electrical architecture, the correlation of the functions of each subsystem in the chassis domain and between the chassis domain and the power domain is also increasingly strong, and the traditional single actuator bench cannot meet the integration and verification of intelligent driving decision, control and other functional modules. In addition, in order to realize intelligent driving, the operation of the vehicle is gradually transferred from the traditional manual driving mode to the man-machine co-driving mode or the automatic driving mode. In the face of different sources of driving instructions and different driving conditions, the traditional electric power steering system and electronic stability system cannot guarantee the optimal vehicle motion control due to their independent ECU control characteristics. Therefore, the line control steering, line control braking and active suspension system have been widely used in intelligent electric vehicle chassis due to their decoupling and fast response characteristics, and the chassis domain control technology can effectively integrate the functions of each subsystem. In addition, the precise and fast response characteristics of the drive motor also make it possible to integrate the control of the chassis and the power domain.

[0003] Patent No. CN113029597A discloses a kind of unmanned vehicle full line control chassis test system, the system includes chassis test execution system, measurement and control system and man-machine interaction system etc., can realize the test of unmanned vehicle full line control chassis in multiple conditions, multiple actuators, multiple motion behaviors. However, this system does not consider the influence of vehicle vertical motion on vehicle system dynamics, so there is a big difference between the test results and the actual vehicle performance. Patent No. CN115452411B discloses a kind of intelligent networked vehicle line control chassis full hardware-in-the-loop coordinated control method and application, which is applied to a system composed of control module, actuator module and vehicle module. The controller coordinates the control of the coupled motion of each subsystem of the intelligent networked vehicle line control chassis in different vehicle conditions, and applies the control method to the hardware-in-the-loop test bench, thereby improving the authenticity and reliability of the test results of the test bench. However, this method only manually divides the working boundary of each subsystem actuator according to the different conditions, gives the corresponding coordinated control signal to the ECU of each subsystem of the line control chassis, and controls each actuator independently, without realizing the integrated control of each subsystem, and cannot guarantee the optimal control response of each actuator.

[0004] In summary, the current hardware-in-the-loop test bench for drive-by-wire chassis vehicles and its control method do not consider the influence of vertical movement of the vehicle on the dynamics of the vehicle system, and most methods only realize coordinated control of vehicle movement through time-sharing and working condition intervention of each actuator subsystem in the chassis domain, lack of consideration of integrated control architecture of each actuator system in the chassis domain or between the chassis and the power domain, and cannot guarantee the authenticity and reliability of the hardware-in-the-loop test results, so as to accurately simulate the actual movement effect of the vehicle. SUMMARY

[0005] The present application aims to overcome the defects of the prior art, fully consider the coupling relationship of multiple actuators, guarantee the authenticity and reliability of the hardware-in-the-loop test results of the vehicle motion control algorithm, and provide a drive-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its power chassis domain integrated control architecture.

[0006] The technical scheme of the drive-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its power chassis domain integrated control architecture comprises eight parts: a driving simulation system, an electric drive system, a drive-by-wire braking system, a drive-by-wire steering system, an active suspension system, a power chassis domain integrated control system, a vehicle real-time simulation system, and a test bench measurement and control system.

[0007] The power chassis domain integrated control system receives driver instructions, road environment and vehicle model information, and response information of each execution system and its load simulation device (including the electric drive system, the drive-by-wire braking system, the drive-by-wire steering system, and the active suspension system), completes control decision and issues control instructions to each execution system,

[0008] Each execution system and its load simulation device receives and executes the control instructions, and feeds back the response state signal to the power chassis domain integrated control system,

[0009] The vehicle real-time simulation system provides vehicle dynamics response information for the power chassis domain integrated control system, and provides road visual information for the driving simulation system,

[0010] The test bench measurement and control system is responsible for test project management, test log recording, test data observation and calibration, and data analysis functions,

[0011] Each system interacts with each other through CAN bus, digital signal and analog signal.

[0012] Preferably, the driving simulation system comprises a steering wheel, a steering column, a steering wheel angle sensor, an accelerator pedal, an accelerator pedal opening sensor, a brake pedal, a brake pedal opening sensor, a display screen, a seat, a driving simulator support and the like. The steering wheel angle sensor is connected to the steering wheel and the steering column. The brake pedal opening sensor is connected to the brake pedal. The accelerator pedal sensor is connected to the accelerator pedal. The display screen, the seat, the brake pedal, the accelerator pedal and the steering column are all mounted on the driving simulator support.

[0013] The driving simulation system collects the steering wheel angle signal input of the driver through the steering wheel angle sensor, collects the brake pedal and accelerator pedal signal input of the driver through the brake and accelerator pedal opening sensors respectively, and simulates the real road view for the driver through the display screen.

[0014] Preferably, the electric drive system comprises a drive motor, a load motor, a gearbox, a torsional damper and a drive system support. The drive motor and the load motor are connected through the gearbox and the torsional damper. The above-mentioned components are all fixed on the drive system support. The gearbox is adjusted to a fixed gear position. The torsional damper reduces the mechanical vibration of the output shaft of the drive motor, thereby improving the stability of the electric drive system. The drive motor receives the demand torque instruction of the powertrain domain integrated control system and responds through the torque control mode. The load motor receives the actual speed instruction of the powertrain domain integrated control system and responds through the speed control mode, thereby simulating the road load.

[0015] More preferably, the brake-by-wire system comprises an integrated electronic hydraulic brake, a hydraulic sensor, a brake pipeline, a brake caliper, a brake disc and a brake system support. The brake pipeline is connected to the integrated electronic hydraulic brake and the hydraulic sensor respectively. The brake disc, the brake caliper and the integrated electronic hydraulic brake are all mounted on the brake system support. The brake caliper is located above the brake disc, and there is a gap between them.

[0016] When braking, the brake cylinder and the valves of the integrated electronic hydraulic brake receive the control instruction of the powertrain domain integrated control system. The inlet valve is opened, the outlet valve is closed, the brake pipeline is pressurized, the brake caliper contacts the brake disc and generates a brake torque, and the hydraulic sensor monitors and feeds back the brake pipeline pressure to the powertrain domain integrated control system. When the braking is cancelled, the inlet valve is closed, the outlet valve is opened, the brake pipeline is depressurized, the brake torque is reduced until it is zero, and the brake caliper and the brake disc are separated.

[0017] More preferably, the steer-by-wire system comprises a double pinion steer-by-wire machine, a steering resistance simulation cylinder and a steering system support. The double pinion steer-by-wire machine and the steering resistance simulation cylinder are mounted on the steering support. One side of the steering knuckle arm of the steering machine is connected to the telescopic rod of the steering resistance simulation cylinder.

[0018] The steering machine receives the front wheel steering angle instruction of the powertrain domain integrated control system, responds through the angle mode, and feeds back the response value to the integrated control system; the steering resistance simulation electric cylinder receives the required steering resistance instruction of the integrated control system, and generates the steering resistance in the opposite direction of the steering knuckle arm movement through the torque control mode.

[0019] More preferably, the active suspension system comprises a continuously variable damper, a coil spring, a road excitation simulation electric cylinder, a force sensor, a displacement sensor, an acceleration sensor, and an active suspension bracket. The road excitation simulation electric cylinder is fixed to the lower bracket of the active suspension system and reciprocates through the speed control mode to simulate road excitation and adjust the amplitude and frequency according to the road grade. The continuously variable damper and the coil spring are connected to the upper bracket and the lower bracket of the active suspension system, respectively. The force sensor is located between the continuously variable damper and the upper bracket, and the acceleration sensor and the displacement sensor are fixed to the upper bracket and the lower bracket, respectively.

[0020] The powertrain domain integrated control system receives the signals of the force sensor, the displacement sensor, and the acceleration sensor, calculates the control current for the continuously variable damper, and realizes the control of the active suspension.

[0021] More preferably, the powertrain domain integrated control system comprises an integrated control module and a signal interaction module.

[0022] The integrated control module comprises a vehicle motion control stability judgment layer, a vehicle motion integrated control layer, and an actuator and load control layer. The module is used to receive the driver's operation instruction, vehicle model, and road environment information, and actuator response information, to realize the stability judgment, integrated control, and actuator and load control of vehicle motion.

[0023] The signal interaction module is used for signal interaction between the integrated control module and other systems, mainly receives the driver's operation instruction, vehicle and road environment simulation information, and actuator response information, and sends control instructions to each actuator.

[0024] More preferably, the vehicle motion stability judgment layer determines the lateral and longitudinal stability of the vehicle through the dissipation energy method, and determines the vertical stability through the roll gradient-pitch gradient-vertical vibration stability determination method.

[0025] The dissipation energy method calculates the dissipation energy at the initial time and the final time by solving the three-degree-of-freedom nonlinear vehicle system differential equation of different vehicle states under the same road adhesion coefficient and front wheel steering angle offline, makes an energy graph in three-dimensional space, determines the lateral and longitudinal stability threshold energy, and thereby divides the boundary between the stable region and the unstable region. On this basis, the stable region is further divided into the critical instability region and the stable region. The nonlinear three-degree-of-freedom vehicle system differential equation is:

[0026]

[0027] wherein, in the formula, m, L f ,L r and I z are vehicle parameters, respectively representing the curb weight, the distance from the front and rear axles to the vehicle center of mass and the moment of inertia of the vehicle about the z axis; v x ,v y and are vehicle motion states, respectively representing the longitudinal speed, lateral speed and yaw angular speed of the vehicle; F yfl ,F yfr ,F yrl ,F yrr are lateral forces of each tire of the vehicle; δ f is the front wheel steering angle. Since the formula is used for judging the XOY plane stability of the vehicle at different longitudinal speeds, only the energy change of the vehicle system in a certain state is considered, and the energy change caused by the driving and braking torque input and by the air resistance is not considered,

[0028] The lateral force calculation formula of each wheel is:

[0029] F y,i = F z,i μDsin(Carctan(Bα i -E(Bα i -arctan(Bα i ))))

[0030] wherein, B, C, D and E are tire lateral force fitting coefficients, respectively representing a tire stiffness factor, a shape factor, a peak factor and a curvature factor; μ is the road adhesion coefficient; α i represents the side slip angle of each tire, i = fl, fr, rl, rr.

[0031] The side slip angles of the front and rear tires are calculated from the vehicle state and parameters:

[0032]

[0033] The vertical force calculation formula of each wheel is:

[0034]

[0035] wherein, a x ,a y ,a z are the longitudinal, lateral and vertical accelerations of the vehicle body, are the pitch and roll angular accelerations of the vehicle body, L w is the wheelbase, and I y,I x Let α and β be the vehicle's rotational inertia about the X and Y axes, respectively; let g be the longitudinal and lateral slopes, respectively; let h be the acceleration due to gravity; and let h be the height of the center of mass of the sprung mass.

[0036] The specific formula for calculating dissipated energy is as follows:

[0037]

[0038] Among them, v x,0 ,v y,0 and Let v be the initial state of the vehicle's motion. x,e ,v y,e and The vehicle's motion state at the final moment is given, and ΔE represents the dissipated energy.

[0039] The roll gradient-pitch gradient-vertical vibration stability discrimination method calculates the vehicle's roll gradient, pitch gradient, and vertical vibration frequency using information such as the vehicle's lateral and longitudinal acceleration, roll angle, and pitch angle. It then creates a vehicle state discrimination diagram in three-dimensional space to classify the vehicle's vertical motion stability. The formulas for calculating the roll / pitch gradient are as follows:

[0040]

[0041] Among them, G pitch G roll Let θ and φ be the pitch and roll gradients, respectively, and let θ and φ be the pitch and roll angles, respectively.

[0042] More preferably, the vehicle motion integrated control layer achieves control through an optimal control method based on a fourteen-degree-of-freedom nonlinear vehicle model, the fourteen-degree-of-freedom nonlinear vehicle motion equation being:

[0043]

[0044] Among them, C f C r C represents the lateral stiffness of the front and rear wheels. D Where A is the drag coefficient, ρ is the frontal area, and A is the windward area. a F is the density of air. d M is the total driving force. d To add yaw moment, F xfl ,F xfr ,F xrl ,F xrr For the longitudinal force of each wheel, F fl ,F fr ,F rl ,F rr For the suspension force at each wheel, m s For the sprung mass, z sLet m be the vertical displacement of the sprung mass. tfl ,m tfr ,m trl ,m trr For each unsprung mass, z rfl ,z rfr ,z rrl ,z rrr z represents the vertical displacement of the road surface under each wheel. tfl ,z tfr ,z trl ,z trr k represents the vertical displacement of each unsprung mass. tfl ,k tfr ,k trl ,k trr For the vertical stiffness of each tire, T df ,T dr T represents the driving torque of each axle. bfl ,T bfr ,T brl ,T brr For the braking torque of each wheel, ω fl ,ω fr ,ω rl ,ω rr For the rotational speed of each wheel, I w R is the moment of inertia of the wheel. w For the wheel radius,

[0045] The formulas for calculating each suspension force are as follows:

[0046]

[0047] Among them, z sfl ,z sfr ,z srl ,z srr Let k be the vertical displacement of the sprung mass at each wheel. sfl ,k sfr ,k srl ,k srr c represents the spring stiffness of the suspension at each wheel. sfl ,c sfr ,c srl ,c srr F is the damping coefficient at each wheel. afl ,F afr ,F arl ,F arr It serves as the primary power source for the suspension at each wheel.

[0048] The motion equations of the 14-DOF vehicle model are rewritten in state-space equation form, where the control variable U = [δ] f M d ,F d ,Fafl ,F afr ,F arl ,F arr ,T df ,T dr ,T bfl ,T bfr ,T brl ,T brr ], state variables

[0049] The objective function of this optimal control problem is:

[0050] J = (YY) ref )Q(YY ref ) T +ΔURΔU T

[0051] in, For output quantity, Y ref Here, ΔU represents the reference value for each output variable, Q and R represent the increments of each control variable, and Q and R are the weight matrices for the output and control variables, respectively. Both are positive definite matrices, reflecting the tracking performance of the controller and the stability of the output.

[0052] The constraints are as follows:

[0053]

[0054] Among them, U min U max and ΔU min ,ΔU max These are the maximum and minimum values ​​of the control quantity and control increment, respectively.

[0055] The weighting principles for the Q and R matrices are as follows: For lateral and longitudinal stability, when the vehicle is within the stable region, the longitudinal velocity v is given priority. x Tracking performance, when the vehicle is in the critical stability region, as stability gradually decreases, v x Tracking weight decrease, lateral velocity v y and yaw rate With increased weighting, when the vehicle is in the instability zone, only v is considered. y , Tracking weights ensure the vehicle's lateral stability; for vertical stability, when the vehicle is within the stable region, the vertical displacement z is given priority. s and vertical velocity Tracking performance ensures vertical comfort; when the vehicle is in the critical stability region, as stability gradually decreases, z s and Tracking weight descent, pitch angle θ, roll angle φ, and pitch angular velocity Rolling angle velocity The weight is increased, when the vehicle is in the unstable region, only θ and φ The tracking performance is guaranteed, the pitch and roll stability is ensured.

[0056] More preferably, the actuator and load control layer is driven by the method based on the minimum tire adhesion utilization rate, the distribution of driving, braking and suspension force is carried out, and the target function is:

[0057]

[0058] Wherein, F x,i , F y,i , F z,i The longitudinal force, lateral force and vertical force of each tire are respectively, i = fl, fr, rl, rr,

[0059] The constraint condition is:

[0060]

[0061] The distribution priority principle follows: when the vehicle lateral and longitudinal stability is poor, F x,i is preferentially met; when the vertical stability is poor, F z,i is preferentially met.

[0062] More preferably, the vehicle real-time simulation system is used for simulation of road, environment and vehicle model,

[0063] The simulation system is used for receiving the response signal of power and chassis system, completing vehicle system dynamics and vehicle-road-environment joint simulation, and outputting road environment information and vehicle state and parameter information,

[0064] The parameters in the simulation system can be adjusted to adapt to different vehicle configurations and road environment scenes.

[0065] More preferably, the bench test control system includes test project management, test data observation and calibration functions,

[0066] The system can observe and analyze the data of driver operation instructions, road environment and vehicle model information, and key states of integrated control algorithm, and calibrate the key parameters of the model and control algorithm. The system can also be used for test project management and daily test log recording.

[0067] Compared with the prior art, the present application has the following beneficial effects:

[0068] 1. The line control chassis has complete functions and high integration degree of power chassis domain: the line control chassis electric vehicle hardware-in-the-loop simulation test bench and power chassis domain integrated control architecture proposed by the application not only includes a driving simulation system, but also covers various actuators of the line control chassis and power system of the electric vehicle, involves various motion modes such as horizontal, vertical and vertical, and can support the test requirements of the coordinated control algorithm of different actuators and power system and the power chassis domain integrated control algorithm. Compared with the prior art, the line control chassis has more complete functions and higher integration degree of power chassis domain.

[0069] 2. Wide test performance coverage: the line control chassis electric vehicle hardware-in-the-loop simulation test bench and power chassis domain integrated control architecture proposed by the application can not only test the power chassis domain integrated control algorithm, but also test and verify the power chassis domain multi-motion mode coupling, the driver's multi-driving style and the underlying control algorithm of the actuator. Compared with the prior art, the test performance coverage is wider. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 The line control chassis electric vehicle hardware-in-the-loop simulation test bench and power chassis domain integrated control architecture in the application are shown in the accompanying drawings.

[0071] Figure 2 The electric drive system structure diagram in the application is shown in the accompanying drawings.

[0072] Figure 3 The line control brake system structure diagram in the application is shown in the accompanying drawings.

[0073] Figure 4 The line control steering system structure diagram in the application is shown in the accompanying drawings.

[0074] Figure 5 The active suspension system structure diagram in the application is shown in the accompanying drawings.

[0075] Figure 6 The vehicle lateral and longitudinal motion stability weight distribution diagram in the application is shown in the accompanying drawings.

[0076] Figure 7 The vehicle vertical motion stability weight distribution diagram in the application is shown in the accompanying drawings. DETAILED DESCRIPTION

[0077] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the application.

[0078] The hardware-in-the-loop simulation test bench of the drive-by-wire chassis electric vehicle of the embodiment and the power chassis integrated domain control architecture, the work flow is as shown in Figure 1 The drive simulation system, the vehicle real-time simulation system, the bench test control system, the power chassis domain integrated control system, the drive-by-wire braking system, the drive-by-wire steering system, the driving system, the active suspension system and other actuator subsystems are included.

[0079] In the embodiment, the drive simulation system provides the road visual information to the driver and collects the operation instructions of the driver.

[0080] In the embodiment, the power chassis domain integrated control system receives the driver instructions, the road environment and vehicle model information and the response information of the power chassis and the load simulation devices of each execution system (including the electric driving system, the drive-by-wire braking system, the drive-by-wire steering system and the active suspension system), completes the control decision and issues the control instructions to each execution system.

[0081] In the embodiment, the electric driving system and the load simulation motor, the drive-by-wire braking system and the load simulation cylinder, the drive-by-wire steering system and the load simulation cylinder, the active suspension system and the road load simulation cylinder receive and execute the control instructions, and the real-time response sensor signals are forwarded to the control module and the vehicle real-time simulation system through the control instruction interaction module of the power chassis domain integrated control system.

[0082] In the embodiment, the vehicle real-time simulation system provides the vehicle dynamics response information to the power chassis domain integrated control system, and provides the road visual information to the drive simulation system.

[0083] In the embodiment, the bench test control system is responsible for the test project management, the test log recording, the observation and calibration of the test data and the data analysis and other functions.

[0084] In the embodiment, the signal interaction is performed among the systems through the CAN bus, the digital signal and the analog signal.

[0085] In the embodiment, the drive simulation system includes the steering wheel, the steering column and the steering wheel angle sensor, the accelerator pedal and the accelerator pedal opening sensor, the brake pedal and the brake pedal opening sensor, the display screen, the seat and the drive simulator support and other components.

[0086] In the embodiment, the drive simulation system collects the steering wheel angle signal input of the driver through the steering wheel angle sensor, collects the brake pedal and accelerator pedal signal input of the driver through the brake and accelerator pedal opening sensors respectively, and simulates the real road visual for the driver through the display screen.

[0087] In this embodiment, the drive system includes a drive motor, a load motor, a drive system support, a torque sensor, a gearbox, a torsional damper and other components. The drive motor and the load motor are connected through the gearbox and are fixed on the drive system support. The structure is shown in Figure 2 .

[0088] In this embodiment, the operating voltage of the drive motor and the load motor is provided by the EA analog power supply, and the operating voltage of the motor controller and the gearbox controller is provided by the low-voltage adjustable power supply. The drive motor is controlled by the torque control mode, and the load motor is controlled by the speed control mode. The drive motor and the load motor follow the total output torque of the power source and the wheel end speed calculated by the real-time controller, respectively. At the same time, the gearbox adopts a fixed gear position to control the motor bench. The motor controller feeds back the motor speed, torque and other motor states in real time, and records the data through CANape.

[0089] In this embodiment, the brake-by-wire system includes an integrated electronic hydraulic brake, a hydraulic sensor, a brake pipeline, a brake caliper, a brake disc brake system support and other components. The integrated electronic hydraulic brake integrates a brake motor and 14 high-speed on-off valves including 4 pressure increasing valves, 4 pressure reducing valves, 2 motor isolation valves, 2 main cylinder isolation valves and 2 pedal isolation valves. The integrated control system controls them through the CAN bus.

[0090] In this embodiment, the brake pipeline is connected to the integrated electronic hydraulic brake and the hydraulic sensor, the brake caliper and the hydraulic sensor, respectively.

[0091] In this embodiment, the brake disc, the brake caliper and the integrated electronic hydraulic brake are respectively installed on the brake system support. The brake caliper is located above the brake disc, and there is a gap between them. When the brake is pressurized, the brake caliper contacts the brake disc and generates a brake torque. When the brake is depressurized, the brake torque decreases to zero, and the two are separated. The structure is shown in Figure 3 .

[0092] In this embodiment, the brake-by-wire system sends control instructions to the 14 high-speed on-off valves and the brake motor through the power chassis domain integrated control system to realize independent control of the brake torque of each wheel. Taking the left front wheel pressurization as an example, the working process of the brake-by-wire system in this mode is described: the power chassis domain integrated control system sends an energy storage instruction to control the brake cylinder to build pressure, opens the motor isolation valve and the left front wheel pressurization valve, and closes the left front wheel depressurization valve to realize the pressurization of the left front wheel. The left front wheel brake hydraulic pressure is collected through the left front wheel pressure sensor, and the signal is sent to the power chassis domain integrated control system to complete the closed-loop control of the left front wheel brake pressure.

[0093] In the embodiment, the steer-by-wire system comprises a double pinion type steer-by-wire machine, a steering resistance simulator electric cylinder and a steering system support, etc. The double pinion type steer-by-wire machine and the steering resistance simulator are installed on the steering system. The steering machine is connected with the telescopic rod of the steering resistance simulator electric cylinder through one side of the steering knuckle arm. The steering resistance simulator electric cylinder is in torque control mode, and generates the steering resistance opposite to the movement direction of the steering knuckle arm. The above structure is shown in Fig. 1. Figure 4

[0094] In the embodiment, the steer-by-wire system can be combined with the vehicle, the road model and the integrated control system of the power chassis domain to realize the hardware-in-the-loop simulation of the steer-by-wire actuator.

[0095] In the embodiment, the steering resistance is calculated by the maximum rack force. The maximum rack force mainly comprises the steering system resistance F f , the tire returning torque M z and the tire steering resistance torque M r . The calculation formula is as follows:

[0096]

[0097] Wherein, s is the effective force ratio of the steering trapezoid at the limit position, and is taken as 200 mm. The steering system resistance is related to the pressing block force of the rack and the piston sealing resistance, and the maximum value F f = 450 N is taken.

[0098] In the embodiment, the tire steering resistance torque M r is obtained by a semi-empirical formula:

[0099]

[0100] Wherein, p is the tire air pressure, taken as 0.22 MP, μ is the sliding friction coefficient between the tire and the road surface, taken as 0.3-0.8, and G l is the vertical load of the steering axle, taken as N. The parameter mainly depends on the vehicle weight and the axle load distribution.

[0101] In the embodiment, the tire returning torque M z is estimated by a magic formula, and the calculation formula is as follows:

[0102] M z,i = F z,i D z sin(C z atan(B z α i +E z (B z α i -atan(B z α i ))))​

[0103] where F z,i denotes the vertical load of each wheel, B z , C z , D z , E z are the stiffness factor, shape factor, peak factor and curvature factor of the tire magic formula for aligning torque, respectively, a i denotes the side slip angle of each wheel, i = fl, fr, rl, rr,

[0104] The side slip angle calculation formula of each wheel is as follows,

[0105]

[0106] In this embodiment, the front wheel steering angle control process of the steer-by-wire system is as follows: the integrated control module in the powertrain and chassis integrated control system sends the required front wheel steering angle to the actuator control instruction layer, the actuator control instruction layer calculates the steering resistance torque, and then sends the required front wheel steering angle and the required steering resistance control instruction to the steer-by-wire system through the CAN bus, and then the steering machine and the steering resistance simulation electric cylinder are actuated to realize the response of the control instruction, and the front wheel steering angle response signal is fed back to the powertrain and chassis integrated control system in real time, so as to complete the closed-loop control of the front wheel steering angle.

[0107] In this embodiment, the active suspension system includes a continuously variable damper, a coil spring, a road excitation simulation electric cylinder, a force sensor, a displacement sensor, an acceleration sensor, and an active suspension bracket, etc. The road excitation simulation electric cylinder is fixed to the lower bracket of the active suspension system, and reciprocating motion is realized through a speed control mode.

[0108] In this embodiment, the road excitation is simulated, the continuously variable damper and the coil spring are connected to the upper bracket and the lower bracket of the active suspension system respectively, the force sensor is located between the continuously variable damper and the upper bracket, and the acceleration sensor and the displacement sensor are fixed to the upper bracket and the lower bracket respectively. The system structure is shown in Figure 5 .

[0109] In this embodiment, the working process of the active suspension system is as follows: the road excitation simulation electric cylinder is actuated to simulate the road excitation, driving the upper bracket, the lower bracket, the coil spring and the continuously variable damper to vibrate. The lower bracket simulates the vibration of the unsprung mass, and the upper bracket simulates the vibration of the sprung mass. The acceleration signal and the displacement signal of the simulated sprung mass and the simulated unsprung mass are collected in real time by the acceleration sensor, the displacement sensor and the force sensor respectively, and the damping force signal can be collected in real time by the force sensor.

[0110] In the embodiment, the acceleration signal, displacement signal and force signal collected by the sensor are sent to the powertrain domain integrated control system to realize observation of the suspension vibration state, and real-time calculation is performed through the vehicle motion integrated control layer to realize decision of the suspension active force, and the actuator and load control layer adjusts the control current and oil pump pressure of the continuously variable damper according to the size of the required suspension active force, so that closed-loop control of the active suspension is realized.

[0111] In the embodiment, the 1 / 4 vehicle vertical model is taken as an example for active suspension control, and the motion differential equation is as follows:

[0112]

[0113] Among them, since the vibration table is fixed with the unsprung mass, the tire has no deformation, and the tire force k t (q-z w ) is consistent with the vibration table thrust F v , and the damping force F c can be measured by a force sensor, so the above motion equation can be rewritten as:

[0114]

[0115] In the formula, m b and m w are the sprung mass and the unsprung mass respectively, K s is the coil spring stiffness, F c and F v are the damping force and the vibration table thrust respectively, which are measured by a sensor and obtained by feedback of a road excitation simulation electric cylinder respectively, z w , z b and are the displacement and acceleration of the sprung mass and the unsprung mass respectively, which are measured by a sensor.

[0116] In the embodiment, the powertrain domain integrated control system includes an integrated control module and a signal interaction module.

[0117] In the embodiment, the integrated control module includes a vehicle motion control stability judgment layer, a vehicle motion integrated control layer and an actuator and load control layer, which respectively receive driver operation instructions and vehicle models, road / environment information, realize vehicle motion control stability analysis, integrated control and actuator control.

[0118] In the embodiment, the signal interaction module is used for signal interaction between the integrated control module and other systems, mainly receives driver operation instructions, vehicle and road environment simulation information, actuator response information, and sends control instructions to each actuator.

[0119] In this embodiment, the vehicle motion control stability judgment layer in the integrated control module determines the lateral and longitudinal motion stability of the vehicle through the energy dissipation method; and determines the vertical motion stability of the vehicle through the roll gradient-pitch gradient-vertical vibration stability judgment method.

[0120] The dissipative energy method solves the differential equations of a three-degree-of-freedom nonlinear vehicle system under different vehicle states with the same road adhesion coefficient and front wheel steering angle offline. It calculates the dissipated energy at the initial and final moments, plots the energy map in three-dimensional space, and determines the layered threshold energy ΔE. th This achieves the delineation of the stable and unstable regions. Based on this, the stable region is further divided into a critical instability region and a stable region. In this embodiment, the boundary is taken as 0.9ΔE. th The differential equation for the nonlinear three-degree-of-freedom vehicle system is as follows:

[0121]

[0122] Where, m,L f ,L r and I z Here are the vehicle parameters, representing the curb weight, the distance from the front and rear axles to the vehicle's center of gravity, and the vehicle's moment of inertia about the z-axis, respectively; v x ,v y and For the vehicle's motion state, F represents the vehicle's longitudinal velocity, lateral velocity, and yaw rate, respectively; yfl ,F yfr ,F yrl ,F yrr These represent the lateral forces of each tire on the vehicle; δ f Let be the front wheel steering angle. Since this formula is used to determine the XOY plane stability of a vehicle at different longitudinal speeds, it only considers the energy changes of the vehicle system's spontaneous motion under a certain state, and does not consider the energy changes caused by the input of driving and braking torques and by air resistance.

[0123] The specific formula for calculating dissipated energy is as follows:

[0124]

[0125] Among them, v x,0 ,v y,0 and Let v be the initial state of the vehicle's motion. x,e ,v y,e and Let ΔE represent the vehicle's motion state at the final moment, and let ΔE represent the dissipated energy.

[0126] The roll gradient-pitch gradient-vertical vibration stability discrimination method calculates the roll gradient, pitch gradient and vertical vibration frequency of the vehicle through the lateral and longitudinal acceleration, roll angle and pitch angle of the vehicle, and makes a vehicle state discrimination graph in three-dimensional space to realize the division of the vertical motion stability of the vehicle, wherein the roll / pitch gradient calculation formula is:

[0127]

[0128] In the formula, G pit ,G roll are the pitch and roll gradients respectively, θ, φ are the pitch and roll angles respectively, a x ,a y are the lateral and longitudinal accelerations of the vehicle respectively.

[0129] In the embodiment, the model prediction control algorithm based on the fourteen-degree-of-freedom nonlinear vehicle model is used to realize the integrated control of the vehicle motion, and the fourteen-degree-of-freedom nonlinear vehicle motion equation is:

[0130]

[0131] In the formula, C f ,C r are the cornering stiffness of the front and rear wheels, C D is the wind resistance coefficient, A is the windward area, ρ a is the air density, F d is the total driving force, M d is the additional yaw moment, F xfl ,F xfr ,F xrl ,F xrr are the longitudinal forces of the wheels, F fl ,F fr ,F rl ,F rr are the suspension forces at the wheels, L w is the wheel track, m s is the sprung mass, I y ,I x are the moments of inertia of the vehicle around the X and Y axes, α, β are the longitudinal and lateral slopes, g is the gravitational acceleration, h is the height of the center of mass of the sprung mass, z s is the vertical displacement of the sprung mass, m tfl ,m tfr ,m trl ,m trr are the unsprung masses, z rfl ,z rfr ,z rrl ,z rrr are the vertical displacements of the road surface under the wheels, z tfl ,z tfr ,ztrl ,z trr is the vertical displacement of each unsprung mass, k tfl ,k tfr ,k trl ,k trr is the vertical stiffness of each tire, T df ,T dr is the drive torque of each axle, T bfl ,T bfr ,T brl ,T brr is the braking torque of each wheel, ω fl ,ω fr ,ω rl ,ω rr is the rotational speed of each wheel, I w is the moment of inertia of the wheel, R w is the wheel radius.

[0132] The calculation formula of each suspension force is:

[0133]

[0134] where z sfl ,z sfr ,z srl ,z srr is the vertical displacement of each wheel of the sprung mass, k sfl ,k sfr ,k srl ,k srr is the spring stiffness of each suspension at the wheel, c sfl ,c sfr ,c srl ,c srr is the damping coefficient at each wheel, F afl ,F afr ,F arl ,F arr is the active force of each suspension at the wheel.

[0135] The motion equation of the fourteen-degree-of-freedom vehicle model is rewritten into the state space equation form, and the state space equation control quantity U = [δ f ,M d ,F d ,F afl ,F afr ,F arl ,F arr ,T df ,T dr ,T bfl ,T bfr ,T brl ,T brr ], and the state quantity

[0136] The objective function of the model predictive control algorithm is:

[0137]

[0138] in, For output quantity, Y ref Let be the reference value for each output, ΔU be the increment of each control variable, and Q and R be the weight matrices for the output and control variables, both positive definite matrices reflecting the tracking performance and output stability of the controller. p N c These are the prediction step size and the control step size, respectively. In this embodiment, N is taken as N. p =5,N c =3.

[0139] The constraints are:

[0140]

[0141] Among them, U min U max and ΔU min ,ΔU msx These are the maximum and minimum values ​​of the control quantity and control increment, respectively.

[0142] Q,R matrix weight allocation principle: For the vehicle's lateral and longitudinal motion stability, the weight allocation principle is as follows: Figure 6 As shown, when the vehicle is in a stable region, the longitudinal velocity v is given priority. x Tracking performance, longitudinal velocity weight γ x =1, lateral stability weight As stability decreases, it gradually increases. When the vehicle is in the critical stability region, as stability gradually decreases, the longitudinal velocity weight γ... c Gradually decrease, 0 < γ c <1, lateral stability weight When the vehicle is in the instability zone, only v is considered y , Tracking weights, To ensure the lateral stability of the vehicle; for the vertical stability of the vehicle's motion, the weighting principle is as follows: Figure 7 As shown, when the vehicle is within the stable region, the vertical displacement z is given priority. d and vertical velocity Tracking performance, vertical weight γ z =1, ensuring comfort, pitch angle θ, roll angle φ, and pitch angular velocity. roll rate weight γ θ,φ Gradually increase, 0 < γ θ,φ<1; when the vehicle is in the critical stability region, the vertical weight γ z decreases gradually, 0 < γ z <1, the pitch and roll weights γ θ,φ = 1; when the vehicle is in the unstable region, only θ and φ are tracked, the pitch and roll stability is ensured preferentially, γ θ,φ = 1, γ z = 0.

[0143] In the embodiment, the actuator and load control layer distributes the driving, braking and suspension force based on the minimum tire adhesion utilization rate, and the objective function of the optimization distribution problem is:

[0144]

[0145] wherein F x,i , F y,i and F z,i are the longitudinal force, lateral force and vertical force of each tire respectively, and i = fl, fr, rl, rr.

[0146] The constraint condition is:

[0147]

[0148] wherein μ is the road adhesion coefficient.

[0149] The distribution priority principle is as follows: when the vehicle lateral and longitudinal stability χ sta,XOY is poor, i.e., χ sta,XOY < χ sta,Z , F x,i is preferentially satisfied; when the vehicle vertical motion stability χ sta,Z is poor, i.e., χ sta,XOY ≥ χ sta,Z , F z,i is preferentially satisfied.

[0150] In the embodiment, the vehicle real-time simulation system is used for simulation of the road, environment and vehicle model, the simulation system is used for receiving the response signal of the power and chassis system, completes vehicle system dynamics and vehicle-road-environment joint simulation, and outputs road environment information and vehicle state and parameter information, the parameters in the simulation system are adjustable, and are used for adapting different vehicle configurations and road environment scenes.

[0151] In the embodiment, the testbed control system includes test item management, test data observation and calibration, etc. The system can observe and analyze data of driver operation instruction, road environment and vehicle model information, integrated control algorithm key state, calibrate key parameters of the model and control algorithm, and can also be used for test item management and daily test log recording.

[0152] The above merely describes the preferred embodiments of the present application, and does not limit the present application in any way. Any person skilled in the art can make any equivalent replacement, modification or change to the technical solutions and technical contents disclosed in the present application without departing from the scope of the technical solutions of the present application, and such still falls within the protection scope of the present application.

Claims

1. A by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its power chassis domain integrated control architecture, characterized in that, The application relates to a vehicle test system, which comprises a driving simulation system, an electric drive system, a brake-by-wire system, a steer-by-wire system, an active suspension system, an integrated control system of a power chassis domain, a vehicle real-time simulation system and a bench test control system. The driving simulation system provides road visual information for a driver and collects operation instructions of the driver. The integrated control system of the power chassis domain receives the operation instructions of the driver, road environment and vehicle model information, response information of each execution system of the power chassis domain and its load simulation device and parameters marked by the bench test control system, completes control decision and issues control instructions to each execution system, wherein the execution system of the power chassis domain and its load simulation device receive and execute the control instructions and feed back response state signals to the integrated control system of the power chassis domain. The vehicle real-time simulation system provides whole vehicle dynamic response information for the integrated control system of the power chassis domain, completes vehicle system dynamics and vehicle-road-environment joint simulation, outputs road environment information and vehicle state and parameter information and provides road visual information for the driving simulation system. The bench test control system is responsible for test project management, test log recording, observation and marking of test data and data analysis, can observe and analyze data of the operation instructions of the driver, road environment and vehicle model information and key states of the integrated control algorithm, and can mark key parameters of the model and the control algorithm. The systems interact with each other through CAN bus, digital signals and analog signals. The driving simulation system comprises a steering wheel, a steering column and a steering wheel angle sensor, an accelerator pedal and an accelerator pedal opening sensor, a brake pedal and a brake pedal opening sensor and a display screen, a seat and a driving simulator, the steering wheel angle sensor is connected with the steering wheel and the steering column, the brake pedal opening sensor is connected with the brake pedal, the accelerator pedal sensor is connected with the accelerator pedal, the display screen, the seat, the brake pedal, the accelerator pedal and the steering column are all installed on a driving simulator support, the driving simulation system collects driver steering wheel angle signal input through the steering wheel angle sensor, collects driver brake pedal and accelerator pedal signal input through the brake and accelerator pedal opening sensors respectively and simulates real road visual information for the driver through the display screen. The electric drive system comprises a driving motor, a load motor, a gearbox, a torsional damper and a driving system support, the driving motor and the load motor are connected through the gearbox and the torsional damper, the driving motor, the load motor, the gearbox, the torsional damper and the driving system support of the electric drive system are all fixed on the driving system support, the driving motor receives demand torque instructions of the integrated control system of the power chassis domain and responds through a torque control mode, the load motor receives actual speed instructions of the integrated control system of the power chassis domain and responds through a speed control mode and simulates road load.

2. The x-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its powertrain chassis domain integrated control architecture according to claim 1, wherein, ​ 3. The x-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its powertrain chassis domain integrated control architecture according to claim 1, wherein, ​ 4. The x-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its powertrain chassis domain integrated control architecture according to claim 1, wherein, The line control brake system comprises an integrated electronic hydraulic brake, a hydraulic sensor, a brake caliper, a brake disc, a brake pipeline and a brake system support, the integrated electronic hydraulic brake and the hydraulic sensor are connected respectively, the brake caliper and the hydraulic sensor are connected, the brake disc, the brake caliper and the integrated electronic hydraulic brake are installed on the brake system support respectively, the brake caliper is located above the brake disc, and a gap exists between the brake caliper and the brake disc, During braking, the brake cylinder of the integrated electronic hydraulic brake and each valve receive the control instruction of the power chassis integrated control system, the inlet valve is opened, the outlet valve is closed, the brake pipeline is pressurized, the brake caliper contacts the brake disc and generates a brake torque, and the hydraulic sensor monitors and feeds back the brake pipeline pressure to the power chassis integrated control system; when braking is cancelled, the inlet valve is closed, the outlet valve is opened, the brake pipeline is depressurized, the brake torque is reduced until it is zero, and the brake caliper and the brake disc are separated.

5. The x-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its powertrain chassis domain integrated control architecture according to claim 1, wherein, The steer-by-wire system comprises a double pinion steer-by-wire machine, a steering resistance simulation cylinder and a steering system support, the double pinion steer-by-wire machine and the steering resistance simulation cylinder are installed on the steering support, one side of the steering machine is connected with the telescopic rod of the steering resistance simulation cylinder, the steering machine receives the required front wheel angle instruction of the power chassis integrated control system, responds through the angle mode, and feeds back the response value to the integrated control system; the steering resistance simulation cylinder receives the required steering resistance instruction of the integrated control system, and generates the steering resistance opposite to the movement direction of the steering knuckle arm through the torque control mode.

6. The x-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its powertrain chassis domain integrated control architecture according to claim 1, wherein, The active suspension system comprises a continuously variable damper, a coil spring, a road excitation simulation cylinder, a force sensor, a displacement sensor, an acceleration sensor and an active suspension support, the road excitation simulation cylinder is fixed to the lower support of the active suspension system, reciprocates through the speed control mode, simulates the road excitation, and adjusts the amplitude and frequency according to the road grade, the continuously variable damper and the coil spring are connected with the upper support and the lower support of the active suspension system respectively, the force sensor is located between the continuously variable damper and the upper support, and the acceleration sensor and the displacement sensor are fixed to the upper and lower supports respectively, The power chassis integrated control system receives the signals of the force sensor, the displacement sensor and the acceleration sensor, sends the control current to the continuously variable damper after calculation, and realizes the control of the active suspension, and the power chassis integrated control system comprises an integrated control module and a signal interaction module.

7. The x-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its powertrain chassis domain integrated control architecture according to claim 6, characterized in that, The integrated control module comprises a vehicle motion control stability judgment layer, a vehicle motion integrated control layer, and an actuator and load control layer, the module is used for receiving the driver operation instruction, the vehicle model and the road environment information, and the actuator response information, realizing the stability judgment, the integrated control and the actuator and load control of the vehicle motion, The signal interaction module is used for the signal interaction between the integrated control module and other systems, mainly receives the driver operation instruction, the vehicle and road environment simulation information and the actuator response information, and sends the control instruction to each actuator.

8. The x-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its powertrain chassis domain integrated control architecture according to claim 7, characterized in that, The vehicle motion stability judgment layer judges the lateral and longitudinal stability of the vehicle by a dissipated energy method, and judges the vertical stability by a roll gradient-pitch gradient-vertical vibration stability judgment method, The dissipated energy method calculates the dissipated energy at the initial time and the final time by solving the differential equations of a three-degree-of-freedom nonlinear vehicle system under different vehicle states with the same road adhesion coefficient and the front wheel steering angle offline, and makes an energy graph in a three-dimensional space to determine the lateral and longitudinal stability layered threshold energy, thereby realizing the division of the stable region and the unstable region. On this basis, the stable region is further divided into a critical instability region and a stable region. The nonlinear three-degree-of-freedom vehicle system differential equation is: Where, m,L f ,L r and I z Here are the vehicle parameters, representing the curb weight, the distance from the front and rear axles to the vehicle's center of gravity, and the vehicle's moment of inertia about the z-axis, respectively; v x ,v y and For the vehicle's motion state, F represents the vehicle's longitudinal velocity, lateral velocity, and yaw rate, respectively; yfl ,F yfr ,F yrl ,F yrr These represent the lateral forces of each tire on the vehicle; δ f Let be the front wheel steering angle. Since this formula is used to determine the XOY plane stability of a vehicle at different longitudinal speeds, it only considers the energy changes of the vehicle system's spontaneous motion under a certain state, and does not consider the energy changes caused by the input of driving and braking torques or by air resistance. The lateral force calculation formula of each wheel is: F y,i = F z,i μD sin(Carctan(Bα i -E(Bα i -arctan(Bα i )))) where B, C, D and E are tire lateral force fitting coefficients, respectively representing tire stiffness factor, shape factor, peak factor and curvature factor; μ is the road adhesion coefficient; α i represents the side slip angle of each tire, i = fl, fr, rl, rr, The side slip angle of the front and rear tires is calculated by the vehicle state and parameters: The vertical force calculation formula of each wheel is: where a x , a y , a z are the longitudinal, lateral and vertical accelerations of the vehicle body, respectively, are the pitch and roll angular accelerations of the vehicle body, respectively, L w is the wheel base, I y , I x are the moments of inertia of the vehicle about the X and Y axes, a, b are the longitudinal and lateral slopes, g is the gravitational acceleration, and h is the height of the mass center of the sprung mass. The dissipated energy calculation formula is specifically: where v x,0 ,v y,0 and are the initial vehicle motion states, v x,e ,v y,e and are the final vehicle motion states, and ΔE is the dissipated energy, The roll gradient-pitch gradient-vertical vibration stability judgment method calculates the roll gradient, pitch gradient and vertical vibration frequency of the vehicle by the lateral and longitudinal acceleration, roll angle and pitch angle of the vehicle, and makes a vehicle state judgment graph in a three-dimensional space to realize the division of the vertical motion stability of the vehicle. The roll / pitch gradient calculation formula is: where G pitch ,G roll are the pitch and roll gradients, respectively, and θ, φ are the pitch and roll angles, respectively.

9. The x-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its powertrain chassis domain integrated control architecture according to claim 8, characterized in that, The vehicle motion integrated control layer realizes control by an optimal control method based on a fourteen-degree-of-freedom nonlinear vehicle model. The fourteen-degree-of-freedom nonlinear vehicle motion equation is: wherein C f ,C r are cornering stiffness of front and rear wheels, C D is a wind resistance coefficient, A is a windward area, p a is an air density, F d is a total driving force, M d is an additional yaw moment, F xfl ,F xfr ,F xrl ,F xrr are longitudinal forces of each wheel, F fl ,F fr ,F rl ,F rr are suspension forces at each wheel, m s is sprung mass, z s is vertical displacement of sprung mass, m tfl ,m tfr ,m trl ,m trr are unsprung masses, z rfl ,z rfr ,z rrl ,z rrr are vertical displacements of road surface under each wheel, z tfl ,z tfr ,z trl ,z trr are vertical displacements of each unsprung mass, k tfl ,k tfr ,k trl ,k trr are vertical stiffnesses of each tire, T df ,T dr are driving torques of each axle, T bfl ,T bfr ,T brl ,T brr are braking torques of each wheel, w fl , w fr , w rl , w rr are rotational speeds of each wheel, I w is a rotational inertia of wheel, R w is a wheel radius, The calculation formula of each suspension force is, where z sfl ,z sfr ,z srl ,z srr is the vertical displacement of the sprung mass at each wheel, k sfl ,k sfr ,k srl ,k srr is the spring rate of the suspension at each wheel, c sfl ,c sfr ,c srl ,c srr is the damping coefficient at each wheel, T afl ,T afr ,F arl ,F arr is the active force of the suspension at each wheel; The motion equations of a fourteen-degree-of-freedom vehicle model are rewritten in the form of state space equations with control variables U = [δ f ,M d ,F d ,F afl ,F afr ,F arl ,F arr ,T df ,T dr ,T bfl ,T bfr ,T brl ,T brr ] and state variables X = [x The objective function of the optimal control is, J = (Y - Y ref )Q(Y - Y ref ) T + ΔURΔU T wherein, Y is an output quantity, ref Y is a reference value of each output quantity, ΔY is an increment of each control quantity, Q, R are weight matrices of the output quantity and the control quantity, and are positive definite matrices, respectively, and reflect a tracking performance of the controller and a stability of the output, respectively, The constraint condition is, where U min , U max , and ΔU min , ΔU max are the maximum and minimum values of the control variable and the control increment, respectively, The weighting principles for the Q and R matrices are as follows: For lateral and longitudinal stability, when the vehicle is within the stable region, the longitudinal velocity v is given priority. x Tracking performance, when the vehicle is in the critical stability region, as stability gradually decreases, v x Tracking weight decrease, lateral velocity v y and yaw rate With increased weighting, when the vehicle is in the instability zone, only v is considered. y , Tracking weights ensure the vehicle's lateral stability; for vertical stability, when the vehicle is within the stable region, the vertical displacement z is given priority. s and vertical velocity Tracking performance ensures vertical comfort; when the vehicle is in the critical stability region, as stability gradually decreases, z s and Tracking weight descent, pitch angle θ, roll angle φ, and pitch angular velocity roll rate With increased weights, when the vehicle is in the instability region, only θ is considered. and φ, Tracking performance should prioritize pitch and roll stability.

10. The x-by-wire chassis electric vehicle hardware-in-the-loop simulation test bench and its powertrain chassis domain integrated control architecture according to claim 7, wherein, The actuator and load control layer distributes the driving, braking and suspension force by a method based on the minimum utilization rate of tire adhesion. The objective function is: Among them, F x,i ,F y,i ,F z,i These represent the longitudinal force, lateral force, and vertical force of each tire, respectively, i = fl, fr, rl, rr. The constraint condition is: The allocation priority follows the principle: when the vehicle transverse and longitudinal stability is poor, F x,i is preferentially met z,i .

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