Vehicle steering body posture and handling stability control method

Abstract

The invention relates to a vehicle steering vehicle body posture and handling stability control method which comprises the following steps: collecting signal input required by control, calculating the total anti-lateral torque of a vehicle through a vehicle body posture feed-forward-feedback controller, calculating the anti-lateral-tilting torque distribution ratio of a front axle and a rear axle through a handling stability feed-forward-feedback controller, and controlling the overall anti-lateral-tilting torque distribution ratio of the front axle and the rear axle through the handling stability feed-forward-feedback controller. And calculating and correcting the total anti-roll moment and the distribution ratio of the front axle and the rear axle through the control comprehensive module, and finally outputting a vertical force control instruction of each suspension angle of the vehicle. The method has the following advantages: 1) vehicle body attitude control and control stability control are comprehensively considered, and the two are optimized at the same time; (2) feedback-feedforward is used for vehicle body attitude control and control stability control, so that the problem of pure feedforward control or feedback control is avoided, and the overall performance of the vehicle is more natural; and 3) steering input and road surface input decoupling is realized, and four height sensors are saved.

Description

Technical Field

[0001] The present invention relates to the field of vehicle-by-wire chassis suspension control, especially to the field of full-active suspension technology that uses a motor system as the power source and realizes real-time adjustment of the vertical force of the suspension through a hydraulic system or a mechanical system. Specifically, it is a method for controlling the vehicle steering body attitude and handling stability. Background Art

[0002] In the field of active suspension technology, the currently widely used is the "slow" active suspension, that is, the air spring. The air spring has the function of height adjustment. However, since the air spring usually takes more than 5 s from the compression limit to the tensile limit or from the tensile limit to the compression limit, the control bandwidth is low and the response time is long, making it difficult to meet the requirements of vehicle attitude dynamic compensation. The double-chamber air spring has the function of stiffness adjustment. However, due to the requirements of vehicle comfort, the stiffness cannot be set infinitely large, and due to physical structure limitations, it is even more impossible to be set to negative stiffness. Therefore, the stiffness adjustment can only suppress vehicle roll to a certain extent during steering, but cannot continuously control the vehicle roll motion, let alone make the vehicle generate a roll angle in the opposite direction.

[0003] In the field of semi-active suspension, the currently widely used is the continuously variable damping shock absorber. The damping force is a passively generated force, whose value is equal to the damping coefficient multiplied by the relative motion speed, and its direction is opposite to the direction of the relative speed. Due to the requirements of comfort, the damping of the shock absorber cannot be adjusted infinitely large, and the continuously variable damping shock absorber cannot actively output the suspension force. From the characteristics of the damping force, it can be seen that the damping force can only reduce the rate of roll to a certain extent, and it is even more impossible to make the vehicle generate a roll angle in the opposite direction. Therefore, the control effect on vehicle roll is limited.

[0004] The active suspension that uses a motor system as the power source and realizes real-time adjustment of the vertical force of the suspension through a hydraulic system or a mechanical system can quickly, real-time, and arbitrarily adjust the compression and tension of each suspension within the output capacity range of the actuator, and has the potential to improve the vehicle body attitude and handling stability during steering.

[0005] There are few prior arts that consider the integration of vehicle body attitude control and handling stability control for full-active suspension. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a method for controlling the vehicle steering body attitude and handling stability, which can simultaneously optimize the vehicle steering body attitude and handling stability, and improve the comfort of the passengers and the safety of the vehicle.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A method for controlling the vehicle steering body attitude and handling stability includes the following steps:

[0009] Step 1: Collect vehicle signals related to control, including steering wheel angle, angular velocity, steering torque, vehicle speed, etc.

[0010] Step 2: The vehicle body attitude feedforward-feedback controller calculates the total anti-roll moment M of the vehicle Tol , including M Tol_Comp , M Tol_Norm , M Tol_Spt , etc.

[0011] Sub-step 2-1: The vehicle body attitude feedforward controller receives signals such as steering wheel angle, angular velocity, steering torque, and vehicle speed, and calculates the first anti-roll moment M Ff , including M Ff_Spt , M Ff_Norm , M Ff_Spt . The calculation method can adopt the look-up table method or the online calculation method. The look-up table method obtains the optimal control quantity curve through offline simulation in advance and stores it inside the software, and obtains the current control quantity by looking up the table with input signals such as steering wheel angle, angular velocity, vehicle speed, etc. The online calculation method can use a feedforward controller G ff of the following types, including but not limited to:

[0012] Sub-step 2-2: Combine the control variables of the vehicle body attitude feedforward controller and the feedback controller to obtain the total anti-roll moment M of the vehicle Tol , including M Tol_Comp , M Tol_Norm , M Tol_Spt . Among them, the control variables of the vehicle body attitude feedforward controller come from sub-step 2-1, and the control variables of the vehicle body attitude feedback controller come from sub-step 2-6 (to avoid algebraic loops, the control variables need to be delayed by one cycle). The methods for combining control variables include the superposition method and the weighted summation method. Sub-step 2-3: Output the total anti-roll moment M of the vehicle Tol , including M Tol_Comp , M Tol_Norm , M Tol_Spt . On the one hand, it is output to Step 4, and on the other hand, it is output to Sub-step 2-4.

[0013] Sub-step 2-4: Estimate the vehicle state based on the non-linear vehicle dynamics model. The input of this non-linear vehicle dynamics model is vehicle speed, steering wheel angle, and steering wheel rotation speed, and the output includes lateral acceleration, yaw angular velocity, rear axle center of mass sideslip angle, vehicle roll motion, etc.

[0014] Sub-step 2-5: Perform signal fusion based on the estimated vehicle state and the actual vehicle state measured by sensors. The signal fusion method is as follows: when the vehicle is in a stable state, use the calculation result of the non-linear vehicle dynamics model; when the vehicle is in an unstable state, use the measured signals of on-vehicle sensors; when the vehicle is in the interval between stable and unstable states, use a fusion method including the Kalman filtering method.

[0015] Sub-step 2-6: Perform feedback control based on the vehicle state after signal fusion output in Sub-step 2-5, calculate and output the anti-roll moment M Ff , including M Ff_Comp , M Ff_Norm , M Ff_Spt . The feedback control methods include look-up table, proportional control, PI control, PD control, PID control, sliding mode control, MPC control, and robust control.

[0016] Step 3: The handling stability feedforward-feedback controller calculates the anti-roll moment distribution ratio f between the front and rear axles. The anti-roll moment distribution ratio f between the front and rear axles includes f suitable for a leisure and comfortable driving style Comf , f suitable for a daily driving style Norm , f suitable for an aggressive driving style Spt . It mainly includes Sub-steps 3-1 to 3-4.

[0017] Sub-step 3-1: The handling stability feedforward controller receives signals such as the steering wheel angle, angular velocity, steering torque, and vehicle speed, and calculates the first anti-roll moment distribution ratio f between the front and rear axles, including: f Ff_Comf , f Ff_Norm , f Ff_Spt . The calculation method can use the look-up table method or the online calculation method. The look-up table method obtains the optimal control quantity curve through offline simulation in advance and stores it inside the software, and obtains the current control quantity by looking up the table through input signals such as the steering wheel angle, angular velocity, vehicle speed, etc. The online calculation method uses the feedforward controller G ff .

[0018] Sub-step 3-2: The handling stability feedback controller receives signals such as the measured vehicle yaw rate, lateral acceleration, and rear axle centroid sideslip angle, and calculates the second anti-roll moment distribution ratio f between the front and rear axles, including: f Fb_Comf , f Fb_Norm , f Fb_Spt . The feedback control methods include look-up table, proportional control, PI control, PD control, PID control, sliding mode control, MPC control, and robust control.

[0019] Sub-step 3-3: Synthesize the control variables of the handling stability feedforward controller and the feedback controller to obtain the anti-roll moment distribution ratio f between the front and rear axles, including: f Comf , f Norm, f Spt . Among them, the control variable of the handling stability feedforward controller comes from sub-step 3-1, and the control variable of the vehicle body attitude feedback controller comes from sub-step 3-2. The methods of synthesizing control variables include the superposition method and the weighted summation method.

[0020] Sub-step 3-4, output the front and rear axle anti-roll moment distribution ratio f to step 4, including: f Comf , f Norm , f Spt .

[0021] Step 4, synthesize vehicle body attitude control and handling stability control. In this step, the final front and rear axle anti-roll moments M Frt_Comp and M Rr_Comp are calculated. It mainly includes sub-steps 4-1 to 4-6.

[0022] Sub-step 4-1, selection of the total vehicle anti-roll moment, output the total vehicle anti-roll moment M Tol . Select a suitable total vehicle anti-roll moment M Tol according to the current driving style evaluation result. The mapping relationship between the driving style and the total anti-roll moment should be defined by the vehicle manufacturer.

[0023] Sub-step 4-2, compensation and correction of the total vehicle anti-roll moment, output the corrected total anti-roll moment M Tol_Comp . Compensate and correct the total vehicle anti-roll moment according to the current vehicle state and system state, including but not limited to: ① correction based on the vehicle available power limit; ② correction based on the motor available power and available torque; ③ correction based on the active suspension system fault state; ④ compensation based on the full active suspension system efficiency; ⑤ compensation based on the non-linearity of the full active suspension structure; ⑥ compensation based on the inertia of the full active suspension actuator.

[0024] Sub-step 4-3, selection of the front and rear axle anti-roll moment distribution ratio, output the front and rear axle anti-roll moment distribution ratio f. Select a suitable front and rear axle anti-roll moment distribution ratio according to the current driving style evaluation result. The mapping relationship between the driving style and the total anti-roll moment should be defined by the vehicle manufacturer.

[0025] Sub-step 4-4, compensation and correction of the front and rear axle anti-roll moment distribution ratio f, output the compensated and corrected front and rear axle anti-roll moment distribution ratio f Comp ; Compensate and correct the front and rear axle anti-roll moment distribution ratio f according to the current vehicle state and system state, including but not limited to adjusting the front and rear axle anti-roll moment distribution ratio f based on the external system request.

[0026] Sub-step 4-5, calculate the front and rear axle anti-roll moments M Frt_Comp and M Rr_Comp :

[0027]

[0028] Sub-step 4-6, output the anti-roll moment M of the front and rear axles Frt_Comp and M Rr_Comp to step 5.

[0029] Step 5, according to the anti-roll moments M Frt_Comp and M Rr_Comp , combined with the front and rear wheelbases of the vehicle, convert to obtain the vertical control forces F FL 、F FR 、F RL 、F RR .

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1) Considering the comfort and handling stability of the vehicle during steering, the body attitude feedforward-feedback control and the handling stability feedforward-feedback controllers are respectively designed, and the two are organically combined to achieve the goal of improving the riding comfort and driving safety of the vehicle during steering;

[0032] 2) Both the body attitude control and the handling stability control adopt the feedforward-feedback control architecture, avoiding the problems of slow response and large overshoot when there is only feedback control, thus making the attitude control and the handling stability control more "natural", and at the same time avoiding the problem of poor robustness to model parameter perturbations when there is only feedforward control.

[0033] 3) The body attitude feedback control signal comes from the result of the fusion of the estimated signal and the measured signal of the nonlinear vehicle model. On the one hand, it avoids the influence of the body attitude control during vehicle steering by the road surface input, thereby improving the stability of the system. On the other hand, it saves 4 body height sensors and reduces the system cost. Description of the Drawings

[0034] Figure 1 is the system block diagram of the present invention.

[0035] Figure 2 is the main step flow chart of the present invention.

[0036] Figure 3 is the sub-step flow chart of the main step 2 of the present invention.

[0037] Figure 4 is the sub-step flow chart of the main step 3 of the present invention.

[0038] Figure 5 is the sub-step flow chart of the main step 4 of the present invention. Detailed Embodiment

[0039] To enable those skilled in the art to better understand this application, the following further describes this application in detail in conjunction with the embodiments of the accompanying drawings.

[0040] As Figure 1 shown, a method for controlling a vehicle's steering body posture and handling stability includes the following modules:

[0041] 1. Module 1 is a signal input module, whose main function is to provide signals such as steering wheel angle, steering wheel speed, steering wheel torque, vehicle speed, etc. for the present invention;

[0042] 2. Module 2 is a body posture feedforward controller module, whose main function is to calculate the feedforward component of the total anti-roll moment of the vehicle.

[0043] 3. Module 3 is a non-linear vehicle dynamics model, whose main function is to estimate vehicle states, including but not limited to signals such as lateral acceleration, yaw rate, rear axle sideslip angle, suspension dynamic stroke, etc. This module takes into account the main non-linearities related to vehicle roll, such as suspension spring non-linearity, suspension damping non-linearity, tire non-linearity, etc.

[0044] 4. Module 4 is a vehicle state fusion module, whose main function is vehicle state fusion, and its inputs are the estimated signals from Module 3 and some actual vehicle state signals.

[0045] 5. Module 5 is a body posture feedback controller, whose main function is to calculate the feedback component of the total anti-roll moment of the vehicle.

[0046] 6. Module 6 is a handling stability feedforward controller, whose main function is to calculate the feedforward component of the front-to-rear distribution ratio of the vehicle's anti-roll moment.

[0047] 7. Module 7 is a handling stability feedback controller, whose main function is to calculate the feedback component of the front-to-rear distribution ratio of the vehicle's anti-roll moment.

[0048] 8. Module 8 is a control integration module, whose main function is to calculate the anti-roll moments of the front and rear axles of the vehicle and convert them into vertical control force commands for each suspension angle.

[0049] 9. Module 9 represents a vehicle actually equipped with a full active suspension.

[0050] 10. Single-cycle delay module.

[0051] 11. Single-cycle delay module.

[0052] 12. Single-cycle delay module.

[0053] The above modules operate according to certain steps. For the main steps, refer to Figure 2 , and for the sub-steps, refer to Figure 3 , Figure 4 and Figure 5 . The detailed steps are as follows:

[0054] Step 1, collect vehicle signals related to control, including but not limited to signals such as ① steering wheel angle, ② steering wheel angular velocity, ③ steering wheel input torque, and ④ vehicle speed.

[0055] Step 2, the vehicle body attitude feedforward-feedback controller calculates the total anti-roll moment M of the vehicle Tol , including M Tol_Comp , M Tol_Norm , M Tol_Spt , etc., where: ① M Tol_Comp corresponds to a relaxed and comfortable driving style; ② M Tol_Nor corresponds to a daily driving style; ③ M Tol_Spt corresponds to an aggressive driving style. It mainly includes sub-steps 2-1 to 2-6.

[0056] In the present invention, M Comf causes the vehicle to generate a negative roll angle of 0 to 3 degrees (calibratable on a real vehicle) at any vehicle speed and any steady-state input of the steering wheel angle, so as to offset part of the lateral acceleration and improve the riding comfort; M Norm causes the vehicle to offset 50% to 95% of the roll angle (calibratable on a real vehicle) under any vehicle speed and any steady-state input of the steering wheel angle, improves the riding comfort, and at the same time retains a certain roll angle to help the user perceive the vehicle dynamics; M Spt causes the vehicle to be as close to horizontal as possible under any vehicle speed and any steady-state input of the steering wheel angle, so as to avoid the body roll and the change of steering characteristics caused by it, and at the same time helps the user obtain a more stable driving vision.

[0057] Sub-step 2-1, the vehicle body attitude feedforward controller receives signals such as the steering wheel angle, angular velocity, steering torque, and vehicle speed, and calculates the first anti-roll moment M Ff , including M Ff_Comf , M Ff_Norm , M Ff_Spt , and the calculation method can adopt the look-up table method or the online calculation method. The look-up table method obtains the optimal control quantity curve through offline simulation in advance and stores it inside the software, and obtains the current control quantity by looking up the table through input signals such as the steering wheel angle, angular velocity, vehicle speed, etc. The online calculation method can use a feedforward controller G ff (s) of the following types, and the optional form of its transfer function expression is as follows:

[0058] ① G ff = K ff , this form focuses on feedforward steady-state compensation;

[0059] ② This form focuses on feedforward steady-state supplement and delay compensation;

[0060] ③ This form focuses on calculating feedforward steady-state compensation and dynamic compensation;

[0061] ④ This form takes into account feedforward steady-state compensation, dynamic compensation, and delay compensation.

[0062] Among them, K ff is the steady-state compensation gain, which can be obtained through experimental calibration or theoretical calculation. When performing theoretical calculation, its value is the ratio of the system input gain to the system noise gain under steady-state conditions; s is the Laplace operator; L ff is the system delay time, which can be obtained through experimental calibration or theoretical calculation. When performing theoretical calculation, its value is the difference between the system noise response delay and the system input response delay; T z 、T p are the system input response time constant and the system noise response time constant, respectively, which can be obtained through experimental calibration or dynamic modeling analysis.

[0063] Sub-step 2-2: Combine the control variables of the vehicle body attitude feedforward controller and the feedback controller to obtain the total anti-roll moment M Tol of the vehicle, including M Tol_Comp 、M Tol_Norm 、M Tol_Spt . Among them, the control variables of the vehicle body attitude feedforward controller come from sub-step 2-1, and the control variables of the vehicle body attitude feedback controller come from sub-step 2-6 (to avoid algebraic loops, the control variables need to be delayed by one cycle). The methods for combining control variables include, but are not limited to: ① superposition; ② weighted summation.

[0064] Sub-step 2-3: Output the total anti-roll moment M Tol of the vehicle, including M Tol_Comp 、M Tol_Norm 、M Tol_Spt . On the one hand, it is output to step 4, and on the other hand, it is output to sub-step 2-4.

[0065] Sub-step 2-4: Estimate the vehicle state based on the non-linear vehicle dynamics model. The inputs of this non-linear vehicle dynamics model are vehicle speed, steering wheel angle, and steering wheel rotation speed, and the outputs include, but are not limited to: ① lateral acceleration; ② yaw angular velocity; ③ rear axle center of mass sideslip angle; ④ vehicle roll angle; ⑤ vehicle roll rate; ⑥ vehicle roll angle.

[0066] In the present invention, compared with the conventional linear model, the non-linear vehicle dynamics model takes into account the non-linearity of the tires and the suspension. The non-linearity of the tires is mainly reflected in the non-linearity of the tire cornering stiffness with respect to the vertical load and the longitudinal force, and the non-linearity of the tire self-aligning torque with respect to the vertical load and the longitudinal force. The non-linearity of the suspension is mainly reflected in the non-linearity of the spring stiffness, the non-linearity of the suspension damping, the non-linearity of the bump stop, and the non-linearity of the suspension structure. These non-linear effects are isolated from the linear model and updated by looking up a table, avoiding the accuracy loss caused by linearization and improving the overall estimation accuracy. In sub-step 2-5, signal fusion is performed based on the estimated vehicle state and the actual vehicle state measured by the sensors. The signal fusion method is as follows: when the vehicle is in a stable state, the calculation result of the non-linear vehicle dynamics model is used; when the vehicle is in an unstable state, the measured signal of the on-vehicle sensors is used; when the vehicle is in the interval between the stable and unstable states, a fusion method including the Kalman filtering method is used.

[0067] In the present invention, when the difference between the estimated yaw rate and the true yaw rate is greater than the calibration threshold A1, or the difference between the estimated sideslip angle of the center of mass and the true sideslip angle of the center of mass is greater than a certain calibration threshold B1, it is considered that the vehicle enters an unstable state. When the difference in yaw rate is less than A2 and the difference in sideslip angle of the center of mass is less than B2, it is considered that the vehicle enters a stable state. At other times, it is considered that the vehicle is in the interval between the stable and unstable states.

[0068] In sub-step 2-6, feedback control is performed based on the vehicle state after signal fusion output in sub-step 2-5, and the anti-roll moment M is calculated and output. Ff , including M Ff_Comp , M Ff_Norm , M Ff_Spt . The feedback control methods include but are not limited to: ① looking up a table; ② proportional control; ③ PI control; ④ PD control; ⑤ PID control; ⑥ sliding mode control; ⑦ MPC control; ⑧ robust control.

[0069] In step 3, the front and rear axle anti-roll moment distribution ratio f is calculated by the handling stability feedforward-feedback controller. The front and rear axle anti-roll moment distribution ratio f includes but is not limited to: ① f suitable for a relaxed and comfortable driving style Comf ; ② f suitable for a daily driving style Norm ; ③ f suitable for an aggressive driving style Spt . It mainly includes sub-steps 3-1 to 3-4.

[0070] In the present invention, f Comf is greater than the ratio f Conv of the vehicle's front and rear roll stiffness without an active suspension. The vehicle tends to increase the degree of understeer, is easier to control, and is not prone to oversteer; f Norm is approximately equal to f Conv, the steering characteristics of the vehicle when maintaining the conventional suspension are such that the control intervention is not easily perceptible to the user; f Norm Less than f Conv , the vehicle tends to reduce the understeer degree, making the yaw gain of the vehicle larger, the steering more sensitive, and the cornering speed faster;

[0071] Sub-step 3-1, the handling stability feedforward controller receives signals such as the steering wheel angle, angular velocity, steering torque, and vehicle speed, and calculates the first front and rear axle anti-roll moment distribution ratio f, including: f Ff_Comf 、f Ff_Norm 、f Ff_Spt . The calculation method can adopt the look-up table method or the online calculation method. The look-up table method obtains the optimal control quantity curve through offline simulation in advance and stores it inside the software, and obtains the current control quantity by looking up the table through input signals such as the steering wheel angle, angular velocity, vehicle speed, etc. The online calculation method can use a feedforward controller G including but not limited to the following types ff , and the optional form of its transfer function expression is as follows:

[0072] ①G ff =K ff , this form focuses on feedforward steady-state compensation;

[0073] ② This form focuses on feedforward steady-state supplement and delay compensation;

[0074] ③ This form focuses on calculating feedforward steady-state compensation and dynamic compensation;

[0075] ④ This form takes into account feedforward steady-state compensation, dynamic compensation, and delay compensation.

[0076] Among them, K ff is the steady-state compensation gain, which can be obtained through experimental calibration or theoretical calculation. When calculating theoretically, its value is the ratio of the system input gain to the system noise gain under steady-state conditions; s is the Laplace operator; L ff is the system delay time, which can be obtained through experimental calibration or theoretical calculation. When calculating theoretically, its value is the difference between the system noise response delay and the system input response delay; T z 、T p are the system input response time constant and the system noise response time constant, which can be obtained through experimental calibration or dynamic modeling analysis.

[0077] Sub-step 3-2, the handling stability feedback controller receives signals such as the measured vehicle yaw angular velocity, lateral acceleration, and rear axle centroid sideslip angle, and calculates the second front and rear axle anti-roll moment distribution ratio f, including: f Fb_Comf 、f Fb_Norm 、f Fb_Spt, the methods of feedback control include but are not limited to: ① look-up table; ② proportional control; ③ PI control; ④ PD control; ⑤ PID control; ⑥ sliding mode control; ⑦ MPC control; ⑧ robust control.

[0078] Sub-step 3-3, the comprehensive control of the variables of the handling stability feed-forward controller and the feedback controller to obtain the anti-roll moment distribution ratio f of the front and rear axles, including: f Comf , f Norm , f Spt . Among them, the control variable of the handling stability feed-forward controller comes from sub-step 3-1, and the control variable of the vehicle body attitude feedback controller comes from sub-step 3-2. The methods of comprehensive control of variables include but are not limited to: ① superposition; ② weighted summation.

[0079] Sub-step 3-4, output the anti-roll moment distribution ratio f of the front and rear axles to step 4, including: f Comf , f Norm , f Spt .

[0080] Step 4, the comprehensive control of vehicle body attitude control and handling stability control. This step receives the total anti-roll moment M of the vehicle calculated from step 2 Tol (including M Tol_Comp , M Tol_Norm , M Tol_Spt ) and the anti-roll moment distribution ratio f of the front and rear axles calculated from step 3 (including: f Comf , f Norm , f Spt ), and combines the actual state of the vehicle and the system state of the fully active suspension to calculate the final anti-roll moments M Frt_Comp and M Rr_Comp . It mainly includes sub-steps 4-1 to 4-6. Sub-step 4-1, the selection of the total anti-roll moment of the vehicle, output the total anti-roll moment M of the vehicle Tol . Select the appropriate total anti-roll moment M of the vehicle according to the current driving style evaluation result Tol , and the mapping relationship between the driving style and the total anti-roll moment should be defined by the vehicle manufacturer.

[0081] Sub-step 4-2, the compensation and correction of the total anti-roll moment of the vehicle, output the corrected total anti-roll moment M Tol_Comp . Compensate and correct the total anti-roll moment of the vehicle according to the current vehicle state and system state.

[0082] In the present invention, the compensation and correction of M Tol_Comp include but are not limited to:

[0083] ① Correction based on the vehicle available power limit: when the system power exceeds the vehicle available power, reduce the torque of the system output according to the available power;

[0084] ②Correction based on the available power and available torque of the motor: When the system power exceeds the available power of the active suspension motor,

[0085] Reduce the torque of the system output according to the available power: When the system torque limit exceeds the available torque of the active suspension motor, output according to the available torque value;

[0086] ③Correction based on the fault state of the active suspension system: When a serious fault occurs in the active suspension system, let the system output torque drop to zero at a certain slope;

[0087] ④Compensation based on the efficiency of the full active suspension system: According to the required torque and speed, look up the system efficiency in a table, and inversely calculate the system input torque according to the system efficiency;

[0088] ⑤Compensation based on the non-linearity of the full active suspension structure: Obtain the transmission ratio of the full active suspension according to the table look-up (this value is generally not a constant and changes with the suspension stroke), and compensate by comparing the control force;

[0089] ⑥Compensation based on the inertia of the full active suspension actuator: According to the relative acceleration of the vehicle body and the wheel, obtain the rotational acceleration of the active suspension motor and other rotating components, then obtain the inertial force according to the moment of inertia, and finally apply an active force equal in magnitude and opposite in direction to the inertial force to compensate it.

[0090] Sub-step 4-3, selection of the anti-roll moment distribution ratio between the front and rear axles, and output the anti-roll moment distribution ratio f between the front and rear axles. Select an appropriate anti-roll moment distribution ratio between the front and rear axles according to the current driving style evaluation result. The mapping relationship between the driving style and the total anti-roll moment should be defined by the vehicle manufacturer.

[0091] Sub-step 4-4, compensation and correction of the anti-roll moment distribution ratio f between the front and rear axles, and output the total anti-roll moment distribution ratio f after compensation and correction Comp ; Compensate and correct the anti-roll moment distribution ratio f between the front and rear axles according to the current vehicle state and system state.

[0092] In the present invention, the correction and compensation of f Comp include but are not limited to:

[0093] ①Adjust the anti-roll moment distribution ratio f between the front and rear axles based on the request from an external system.

[0094] Sub-step 4-5, calculate the anti-roll moments M Frt_Comp and M Rr_Comp :

[0095]

[0096] Sub-step 4-6, output the anti-roll moments M Frt_Comp and MRr_Comp to step 5.

[0097] Step 5. According to the roll resisting moments M Frt_Comp and M Rr_Comp , combined with the front and rear wheel track of the vehicle, the vertical control forces F FL 、F FR 、F RL 、F RR of the active suspension are calculated and finally sent to the fully active suspension actuator, including the fully active suspension actuators at the left front, right front, left rear, and right rear corners.

[0098] In the present invention, according to the roll resisting moments M Frt_Comp and M Rr_Comp the vertical control forces F FL 、F FR 、F RL 、F RR of the active suspension are calculated. Since M Frt_Comp and M Rr_Comp have been compensated in step 4-2, there is no need to repeatedly consider the non-linear compensation of the transmission ratio or the inertia compensation, and the calculation can be directly performed according to the front and rear wheel track.

[0099] The method of the present invention simultaneously considers the optimization of the vehicle body posture during steering and the optimization of handling stability, aiming to improve the comfort of the passengers and the safety of the vehicle. First, the method calculates the total roll resisting moment through the vehicle body posture feedforward-feedback controller, and outputting an appropriate roll resisting moment can reduce or eliminate the steering roll, and even generate a negative roll angle to offset part of the centrifugal force, thereby improving the comfort of the passengers. Second, the front and rear axle distribution ratio of the roll resisting moment is calculated through the handling stability feedforward-feedback controller. This ratio affects the wheel load transfer amount between the front and rear axles of the vehicle during steering, and further affects the steering characteristics of the vehicle. By controlling this ratio, the understeer / oversteer characteristics of the vehicle can be dynamically and real-time adjusted, thereby broadening the stability boundary of the vehicle and improving the driving safety and driving pleasure of the vehicle. Finally, the method also considers the selection of feedback signals under different working conditions, the parameter selection for adapting to different driving styles, and the compensation and correction of the roll resisting moment. The method has good engineering feasibility and scalability, takes into account both the vehicle comfort and handling stability, is applicable to different types of fully active suspensions and active stabilizer bars, and has broad application prospects.

[0100] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A vehicle steering body attitude and handling stability control method, characterized in that: The steps include: Step 1: Collect vehicle signals related to control, including steering wheel angle, angular velocity, steering torque, and vehicle speed; Step 2, the vehicle body attitude feedforward-feedback controller calculates the total anti-roll moment M of the vehicle based on the steering wheel angle, angular velocity, steering torque, and vehicle speed Tol ; Step 3: The handling stability feedforward-feedback controller calculates the distribution ratio f of the anti-roll moments of the front and rear axles based on the steering wheel angle, angular velocity, steering torque, and vehicle speed; Step 4: Integrate vehicle body attitude control and handling stability control. Based on the actual state of the vehicle and the system state of the fully active suspension, correct and compensate the total anti-roll moment M of the vehicle calculated in Step 2 Tol and the front and rear axle anti-roll moment distribution ratio f calculated in Step 3, and calculate the front and rear axle anti-roll moments M Frt_Comp and M Rr_Comp ; Step 5: Based on the anti-roll moment M of the front and rear axles Frt_Comp and M Rr_Comp , calculate the vertical forces F FL , F FR , F RL , F RR , and output them to the full active suspension actuators at the left front, right front, left rear, and right rear corners respectively.

2. The control method according to claim 1, characterized in that: Step 2 includes that the vehicle body attitude feedforward controller calculates a first roll resistance moment M based on the steering wheel angle, angular velocity, steering torque, and vehicle speed Ff , and the vehicle body attitude feedback controller calculates a second roll resistance moment M based on the fused vehicle state Fb ; synthesizing the variables of the first roll resistance moment M Ff and the second roll resistance moment M Fb to obtain the total vehicle roll resistance moment M Tol ; wherein, the fused vehicle state is obtained by estimating the vehicle state based on a non-linear vehicle dynamics model, including the yaw angular velocity, the sideslip angle of the center of mass, and the lateral acceleration, and performing signal fusion on the estimated vehicle state and the actual vehicle state measured by the vehicle-mounted sensors 3. The control method according to claim 2, wherein: The signal fusion method is as follows: When the vehicle is in a stable state, the calculation results of the nonlinear vehicle dynamics model are used; when the vehicle is in an unstable state, the measured signals of in-vehicle sensors are used; when the vehicle is in the interval between the stable and unstable states, a fusion method including the Kalman filtering method is used.

4. The control method according to claim 2, characterized in that: Step 3 includes that the handling stability feedforward controller calculates the first front and rear axle roll moment distribution ratio f based on the steering wheel angle, angular velocity, steering torque, and vehicle speed Ff ; manipulation The stability feedback controller calculates the second front-rear anti-roll moment distribution ratio f based on the vehicle's yaw rate, lateral acceleration, and rear axle center of mass sideslip angle. Fb ; For the first front-rear anti-roll moment distribution ratio f Ff and the second front-rear anti-roll moment distribution ratio f Fb The control variables are synthesized to obtain the front-rear anti-roll moment distribution ratio f.

5. The control method according to claim 4, wherein: The handling stability feedback controller calculates the difference between the measured signals of the vehicle and the target yaw angular velocity and the target rear axle sideslip angle of the center of mass, and reduces the absolute value of the difference between the two through feedback control. The feedback control methods include look-up table, proportional control, PI control, PD control, PID control, sliding mode control, MPC control, or robust control.

6. The control method according to claim 4, wherein: The feedforward control calculation methods of the vehicle body attitude feedforward controller and the handling stability feedforward controller adopt the look-up table method or the online calculation method. The look-up table method obtains the optimal control quantity curve through offline simulation in advance, stores it inside the software, and obtains the current control quantity by looking up the table with the input signal; the online calculation method uses the feedforward controller G ff .

7. The control method according to claim 1, wherein: Step 4 includes compensating and correcting the total roll resistance moment M of the vehicle according to the current vehicle state and system state Tol to obtain the corrected total roll resistance moment M Tol_Comp , compensating and correcting the distribution ratio f of the roll resistance moment between the front and rear axles to obtain the corrected distribution ratio f of the total roll resistance moment Comp ; According to the corrected total anti-roll moment M Tol_Comp and the corrected total anti-roll moment distribution ratio f Comp , the anti-roll moments M Frt_Comp and M Rr_Comp of the front and rear axles are calculated.

8. The control method according to claim 7, wherein: Rolling resistance moment M about the longitudinal axis Frt_Comp and M Rr_Comp The calculation formula is as follows 9. The control method according to claim 7, wherein: For the total anti-roll moment M of the vehicle Tol The factors to be considered when making compensation and correction include: vehicle power limit, active suspension power limit and torque limit, active suspension system fault status, full active suspension system efficiency compensation, full active suspension structure nonlinear compensation, and full active suspension system inertia compensation.

10. The control method according to claim 7, characterized in that: During compensation correction, the total roll resistance moment M of the vehicle Tol Select the roll resistance moment distribution ratio f between the front and rear axles. The selection is based on the driver's style.

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