Vibration Suppression for Motor-Driven Uncertain Active Suspensions with Hard Constraints and Analysis of Energy Consumption

The main function of active suspension systems is to suppress vibration resulted from the road roughness and improve passengers' ride comfort, and some time-domain constraints such as mechanical limitation should be taken into consideration when designing active controllers. In this article, a constrained adaptive backstepping control scheme is proposed for the quarter-car suspension with parameter uncertainties, in which the primary control objective is to stabilize the vertical motion of the vehicle body and the suspension mechanical structure constraint can be satisfied in the meanwhile, and energy analysis has been made to demonstrate the potential of energy regeneration and reducing energy consumption for the designed active suspension system. In terms of dealing with the hard constraint, a specific nonlinear filter is employed in order to integrate the main control objective and time-domain constraint into a single controlled variable. In addition, a barrier Lyapunov function is selected to make the defined controlled variable converge to zero and stay in the allowable limit, which means that the vertical motion of the vehicle body can be stabilized and the suspension deflection restriction will not be transgressed. Experiments are carried out on the active suspension test plant to verify the effectiveness of the designed control scheme. Since the high energy consumption of active actuators is one of the drawbacks to be overcome, the energy flow of the dc motors is analyzed in the latter part of this article so as to provide a theoretical basis for energy harvesting design in further study. Finally, the energy consumption of the active suspension plant in experiments is figured out and its potential of energy recovery is demonstrated in detail.