Adaptive Backstepping Tracking Control Of Yaw Stability For Electric Vehicles Considering Model Uncertainty

With the development of society,a number of vehicles can provide us with greater convenience in traveling or working,meanwhile bring about some unavoidable problems,such as environmental concern,energy crisis,and traffic safety,etc.These phenomena inspire people to extensively conduct the research and development of new energy vehicles.As one of the most promising clean-energy vehicles,electric vehicles(EVs)have been emerged and flourished in recent years.An important concern of the EV’s control is vehicle dynamics stability in case of various unexpected driving situations,because EV would inevitably encounter tire sideslip when running fast on the road surfaces with lower adhesion coefficient,or under severe driving maneuvers.Direct yaw moment control can ensure the stability and ride quality of the EVs.The expected external yaw moment can reduce the responses of the sideslip angle and yaw rate,and ensure the driving safety under various working conditions.The influence of model nonlinearities and uncertain parameters on system performance and robustness cannot be ignored.Adaptive backstepping control method can effectively deal with the above challenges while ensuring the system control performances.For the lateral dynamics model of a certain EV,this paper proposed a type of tracking controller based on adaptive backstepping technology,the main contributions of this study are summarized as follows:(1)Two kinds of lateral dynamics models of EV are established,the first one is a three degree-of-freedom(DOF)model considering roll motion for the centralized drive EV,and the second one is a 2-DOF reference model for the distributed drive EV.Based on these two reference models,we can derive the subsequent controller design conveniently.(2)A composite adaptive backstepping robust tracking controller is proposed to improve the lateral dynamics stability for an EV while considering the uncertain parameters and external disturbances.First,based on the 3-DOF reference mode,in the framework of Lyapunov stability theory,the adaptive control law is developed by using backstepping method and dynamic surface control technology,and the sufficient conditions for designing this kind of controller are obtained to ensure its asymptotic stability.Finally,a comparative CarSim-Simulink joint simulation is carried out to verify the effectiveness of the proposed controller under single-lane-change and J-turn maneuvers.(3)To improve the yaw stability of distributed drive EV,based on the 2-DOF reference model,an adaptive backstepping tracking controller using BLF approach is proposed as the upper controller,which is used to generate the desired external yaw moment.Then,by combing the Lyapunov stability theory,the system asymptotic stability of the upper controller is proved.Afterwards,two different torque distribution algorithms are used to derive the lower controller to distribute the external yaw moment to each tire appropriately.In the process of developing this composite tracking controller,the sideslip angle is estimated by the designed observer,and an adaptive law based on projection is developed to estimate the uncertain parameters.Finally,the co-simulation is carried out in CarSim-Simulink environment to validate the effectiveness of the proposed controller.