Hybrid model predictive control of active suspension with travel limits and nonlinear tire contact force

Optimal control techniques have been widely applied to the control of active suspensions. However, most of these applications did not consider the nonlinear effects existing in real suspension systems. In this paper, a constrained nonlinear quarter-car active suspension is simplified and modeled as a piecewise affine (PWA) system where the suspension elements may collide with bump stops or the tire may leave the ground. A hybrid MPC controller is first designed based on this model. The PWA system is then augmented in order to capture the previewed road information to further improve the performance. The resulting hybrid MPC controller is compared to a linear MPC design and a LQ-based controller in simulation. The hybrid MPC designs are shown to achieve better performances in terms of ride and road handling qualities over a large road disturbance.