Chaotic dynamics of the vertical model in vehicles and chaos control of active suspension system via the fuzzy fast terminal sliding mode control

In this paper, the control of chaotic vibrations in vehicle suspension system is studied via a fuzzy fast terminal sliding mode method. Therefore, the nonlinear equations of motion in the vehicle half model are derived initially through the Newton-Euler laws and then these equations are solved by the fourth-order Runge-Kutta method. For analysis of chaos, some techniques including bifurcation diagrams, frequency response, power spectrum, phase plane trajectories, and Poincaré section are used to identify the chaotic behaviors. The chaotic zones are depicted with critical values on the uncontrolled model under the road surface force. In order to eliminate chaotic behavior, the control signals in the active suspension system are generated using the novel fuzzy fast terminal sliding mode control algorithm. The simulation results of the feedback system show that the suspension system can be stabilized the vibrations by efficient fuzzy fast terminal SMC while eliminating irregular chaotic behaviors.