Active chaos control of a heavy articulated vehicle equipped with magnetorheological dampers

Magnetorheological dampers are used for semi-active control of the vehicles vibration because of their useful features such as reducing the dynamic tire forces, improvement the ride quality of the passengers and protection of the vehicle from rollover. The dynamic model of these dampers is nonlinear. Therefore, their nonlinear characteristics can lead to make the chaotic behaviour of the vehicle system if a suitable controller is not used. This paper focuses on the active control of the chaotic behaviour generated by the nonlinear model characteristics of the MR dampers in a typical heavy articulated vehicle. The vehicle nonlinear dynamic study is conducted by detecting the irregular regions using the bifurcation diagrams and Poincare maps. Then, the active controller is proposed to control the chaotic behaviours. The control law was derived based on the backstepping method, and the stability analysis is performed by Lyapunov theorem. Then, optimal backstepping control is designed for controlling the chaos in the vehicle. The simulation results show the vehicle displacements can track a periodic desired motion. The robustness of the proposed controller is studied by inserting external disturbance force. The simulation results show that the vehicle body displacements converge to periodic desired path in spite of the existing external disturbance.