Control of chaos in vehicle lateral motion using the sliding mode variable structure control

A 3-degree of freedom (DOF) nonlinear model including yaw, lateral, and roll motions was constructed, and a numerical simulation of chaotic behavior was performed using the Lyapunov exponent method. The vehicle motion is complex, manifesting double-periodic, quasi-periodic, and chaotic phases, which negatively affects the vehicle lateral stability. To control this chaotic behavior, a controller was designed based on the sliding mode variable structure control (SM-VSC) method. To decrease chattering and further improve lateral stability of the vehicle under extreme operating conditions, the adaptive power reaching law was realized by using a fuzzy control method. The performance of the SM-VSC system was simulated by using Matlab/simulink. The simulation results including the uncontrol, SM-VSC control, and adaptive-reaching SM-VSC control were compared, which demonstrated that the adaptive-reaching SM-VSC control method is more effective in suppressing the chaotic phase of the vehicle lateral motion. The approach proposed in this paper can significantly improve a vehicle's lateral stability under extreme operating conditions.