Yaw Stability And Motor Actuator Failure Fault Tolerant Control Of Distributed-drive Electric Vehicle

As one of the powertrain configurations of electric vehicle,distributed-drive electric vehicle(DEV)has independent driving actuator units,which can independently or collaboratively realize the vehicle body control function,its redundant configuration of multi-power provides convenience for complex body dynamics control.However,the ensuing multi-actuator cooperative control,vehicle transient stability control and driving state parameters estimation are different from traditional vehicles,which is the key to further solve these kind of control problems.In this paper,aiming at DEV,the control strategy of body yaw stability based on sliding mode variable structure theory and the fault-tolerant control method of actuator failure based on parameter estimation and Multi-agent system are proposed.The main research work is as follows:Firstly,a seven-degree-of-freedom dynamic model of vehicle body is built to provide a model basis for following research.Based on analysis of the structure of distributed drive electric vehicle system,the seven-degree-of-freedom dynamic model of vehicle body and the non-linear tyre dynamic model are established,and the sub-system models such as the driver PID model which indicates driving behavior and the driving motor model are established.The vehicle model is built and compared with the CarSim simulation results,which verifies the accuracy and applicability of the built vehicle model.Then,a yaw stability control strategy based on sliding mode variable structure theory is proposed.According to the control principle of body yaw stability,the linear two-degree-of-freedom and seven-degree-of-freedom vehicle model,the direct yaw moment control law based on the wheel longitudinal force is derived.In order to realize yaw moment distribution of driving wheels,a yaw force distribution method based on tyre dynamic load and quadratic programming algorithm is proposed,which takes output characteristics of motor actuator and road adhesion as constraints.The results of sinusoidal corner test show that the proposed yaw stability control strategy and tyre force distribution method can follow the driver's driving intention and further improve vehicle handling stability compared with the average tyre force distribution.Finally,on the basis of the body yaw stability control,aiming at improving the body handling stability of distributed drive electric vehicle while actuator failure,the state parameter monitoring based on Unscented Kalman filter algorithm and the actuator failurefault-tolerant control method based on Agent are proposed.The existing motor failure control methods and vehicle state estimation algorithms are analyzed,and the real-time driving state of the vehicle is determined based on Unscented Kalman filter.The failure control rules and fault-tolerant coordinated control framework are constructed by defining the driving wheel agents,and the failure model is established.Combined with the parameter estimation algorithm,keeping the normal driving state of the vehicle after the actuator fails.The simulation results of line and curve failure driving conditions show that after applying fault-tolerant control strategy,the dynamic parameters of vehicle body can be stabilized in a controllable range,which further improves the fault-tolerant control ability of vehicle actuators and vehicle handling stability.