Semi-Active Suspension Control Using "Fast" Model-Predictive Techniques

The problem considered in this paper is the design and analysis of a control strategy, for semi-active suspensions in road vehicles, based on Model Predictive Control (MPC) techniques. The optimal control law we compute using predictive techniques aims to optimize, the suspension performance, by minimizing a quadratic cost function while ensuring that the magnitude of the forces generated by the control law satisfies the physical constraints of passive damping. The on line computation difficulties related to the predictive control law are overcome by means of a “fast” implementation of the MPC algorithm. The estimation of the system state variable needed for control law computation is provided by a suitable “robust” observer, whose accuracy is not affected by variation of the system parameters (i.e. masses, damping and stiffness coefficients, etc.). A performance comparison with well established semi-active control strategies such as Sky-Hook control and clipped control is presented. The achievable performance improvements of the proposed design procedure over Sky-Hook and clipped control laws are showed by means of results obtained from a nonlinear model which proved to give accurate simulation of the overall vertical dynamics of a vehicle equipped with continuous damping suspension systems. ∗ corresponding author This research was supported in part by funds of Ministero dell’Istruzione dell’Università e della Ricerca under the Project “Robustness and optimization techniques for control of uncertain systems”. M. Canale, M. Milanese, C. Novara and Z. Ahmad are with the Dipartimento di Automatica e Informatica, Politecnico di Torino, Corso Duca degli Abruzzi 24 10129 Torino Italy [email protected], [email protected], [email protected], [email protected]