Saturated Adaptive Backstepping Control for Uncertain Nonlinear Active Suspension Systems with Prescribed Performance

In this paper, an adaptive control method with prescribed performance for active suspension systems with uncertain model parameters is proposed. In order to stabilize the vertical displacement and guarantee the suspension hard constraints, a saturated adaptive backstepping controller based on barrier Lyapunov function is designed. Specifically, a prescribed performance function (PPF) is used to adjust the convergence rate of error. Compared with other tracking control methods, the PPF-based scheme can regulate performance of the vertical motion without any priori knowledge of initial state value. Furthermore, an auxiliary system is first introduced to compensate the phenomenon of input saturation and a novel adaptive law is employed to update the sprung mass online. Finally, an experimental example is shown to verify the merit and effectiveness of the proposed controller.