Research On Coordinated Control Based On Vehicle EPS And ESP

The simultaneous assembly of Electric Power Steering(EPS)and Electronic Stability Program(ESP)on the vehicle is of great significance for improving vehicle stability and safety.However,when the vehicle encounters emergency conditions,it is difficult to maintain the stability of the vehicle by relying solely on the EPS system or the ESP system,and even leads to insufficient steering or excessive steering.To address these issues,this paper studies EPS system control based on BAS-PID(Beetle Antennae Search Algorithm,BAS)algorithm,EPS and ESP coordinated control based on function allocation and EPS and ESP coordinated control based on state estimation.The specific work is as follows:Aiming at the problems of slow response speed and unobvious assist effect of EPS system,a control method based on beetle antennae search algorithm and conventional PID strategy is proposed to improve the steering performance of the vehicle.Firstly,the kinematics characteristics of the steering system are analyzed,and the EPS overall model and the BAS-PID controller model are established.Then,the BAS algorithm is used to adjust the parameters of the PID controller in real time,and the PID parameter tuning problem is transformed into a kind of target optimization problem in three-dimensional space.The absolute integral function of time and current error is used to evaluate the convergence of the BAS algorithm.Finally,the verification experiment is carried out in the AMESim/Simulink simulation platform.The results show that the BAS-PID algorithm is superior to other algorithms in terms of peak value,adjustment time and overshoot of steering wheel output torque and controller output voltage,which improves the system response speed and steering portability.Aiming at the problem that EPS and ESP single system is difficult to solve the problem of vehicle steering instability,a coordinated control strategy of EPS and ESP based on function allocation is proposed.By analyzing the coupling between EPS and ESP,a hierarchical control model is established.The upper coordination controller designs a fuzzy controller based on the logical relationship between the ideal and actual yaw rate difference and the ideal and actual centroid sideslip angle difference to achieve a reasonable distribution of the weight coefficients of the EPS controller and the ESP controller.The lower controller receives the weight coefficient of the upper controller,and uses the PID algorithm to control the assist torque of the EPS system and the braking torque of the ESP system.The comparative experiments are carried out in the Carsim/Simulink simulation platform.The results show that the coordinated control of EPS and ESP based on function allocation can reduce the peak value and root mean square value of the stability index,and effectively improve the stability and safety of the vehicle under emergency conditions.A coordinated control strategy of EPS and ESP based on state estimation is proposed to solve the problem that vehicles under complex working conditions are susceptible to noise interference and yaw rate and sideslip angle are difficult to obtain through sensors.Based on the coordinated control of EPS and ESP based on function allocation,an extended Kalman filter observer is added to realize the state estimation of vehicle yaw rate and sideslip angle.The coordinated control system takes the difference between the ideal value and the estimated value of the yaw rate and the difference between the ideal value and the estimated value of the sideslip angle as the input,and assigns the corresponding weight coefficient to the EPS system and the ESP system through the fuzzy controller to realize the control of the steering and braking system.The effectiveness of the state estimation algorithm and the coordinated control strategy is verified by simulation experiments.