Dynamic Model And Trajectory Tracking Control Method For Tractor-semitrailer Vehicles

Tractor-semitrailer vehicles play a crucial role in highway freight transportation due to their advantages,such as large load,high efficiency and specialization.However,it lead to the occurrence of unstable and dangerous accidents easily,for instance,jackknife in the process of automated driving because of its structural characteristics such as large mass,high center of gravity and mutual coupling at hitch point,and so on.Usually,there exists three essential components for achieving the automated driving of the tractor-semitrailer,i.e.,perception,decision and control,where trajectory tracking control is an important branch of the control component.Given that,this paper derives control oriented tractor-semitrailer vehicle kinematica and dynamic models,and proposes a coordinated trajectory tracking control strategy,by which the lateral instability can be effectively prevented during reference trajectory tracking control processes.Firstly,in order to construct controllers of trajectory tracking and lateral dynamic,kinematic model considering longitudinal,lateral,yaw and jackknife effects as well as dynamic model allowing for longitudinal,lateral and yaw motions are separately estabilished.Specifically,the kinematic model is used for characterizing the kinematical behaviors and designing trajectory tracking controller,and the dynamic model is constructed to reveal the dynamic state and develop lateral stability controller.Secondly,aiming at anti-jackknife trajectory tracking control of the tractor-semitrailer vehicle in reversing perpendicular parking maneuver,jackknife condition of the vehicle is analyzed,and the maximum hitch angle without jackknife in such maneuver is derived,which can be regarded as the candidate hitch angle constraint conditions.To readily cope with the mentioned cosntraints,model redictive control(MPC)technique is employed for realizing the effective tracjectory tracking performance based on the induced kinematical model.In the end,comparative simulations with/without hitch angle constraints in reversing perpendicular parking maneuver are performed to validate the effectiveness of the developed trajectory tracking controller and highlight the superiority of anti-jackknife tracjectory tracking control strategy.Thirdly,in the light of the effective dynamic characteristics in curved road at high speed,a longitudinal and lateral coordinated control strategy is proposed,where a velocity controller is presented based on the longitudinal dynamic model using sliding mode control(SMC)technique in the presence of uncertain aerodynamic drag.Together with the lateral motion controller based upon MPC combined with lateral dynamic and kinematic model,the coordinated control strategy of longitudinal and lateral directions is developed for achieving the effective control.Lastly,simulations in curved road at high speed scenario confirm the feasibility and effectiveness of the proposed control strategy.Finally,using the mentioned coordinated control strategy,together with the lateral stability,a simulation case in lane-change trajectory tracking control maneuver is implemented based on the direct yaw control idea.With the coordinated control strategy as well as the MPC and SMC techniques,the lateral stability of tractor-semitrailer vehicle during lane-change maneuver is further enhanced,in which lateral instability can be prevented effectively.Numerical simulations are performed in MATLAB/Simulink environment to verify the feasibility and effectiveness of the developed control strategy and methods in improving trajectory tracking capacity and dynamic stability ability.