Nonlinear Control of Vehicle Active Suspension Considering Actutor Dynamics

Considering the nonlinear characteristic of hydraulic actuators is very important in designing the controller of automobile active suspension system. To show the importance of this effect, two nonlinear control methods are employed in this paper. At first, a controller is designed by a combined LQR and backstopping (CLB) nonlinear technique. In this method, the nonlinear model is linearized in one step of the design process. At the second one, a sliding mode controller is designed by the suitable selection of the sliding surface. In this way, the well-defined sky hook linear model is selected as the reference model to be tracked by the nonlinear sliding controller. In order to decrease the vertical accelerations and improve the behavior of the reference model, the sky hook model is controlled beforehand by the LQR method. The simulation results and robustness analysis show that the performance of the sliding controller, which is based on the non-linear model, is better than the performance of the CLB controller that uses linearization in one step of the design process.