Hybrid model predictive control on lifting and dropping vehicle body via asymmetric damping adjustment

Abstract

For suspension systems with asymmetric damping during the extension and compression strokes, the equilibrium position of the vehicle body will lift or drop. Inspired by this phenomenon, a novel idea of control the vehicle height by adjusting asymmetric damping via adjustable-damping semi-active suspensions is proposed. Meanwhile, a methodology to implement this idea is also presented. By accounting for nonlinear factors, such as the nonlinear constraints of the output damping force of an adjustable-damper and the logic control conditions of the asymmetric damping adjustment, this control system was designed as a hybrid system. Hybrid model predictive control theory was used to design this controller, and the switching control problem was transformed into a continuous-rolling finite-time-domain optimisation control problem. The feasibility of this idea was proven by simulations for single-wheel vehicle height control. The proposed idea makes it possible to use semi-active actuators for vehicle height adjustment to realise the control effect achieved by active actuators. Moreover, it has lower energy consumption, lower cost and faster response than active suspension, and provides a new method for short-term vehicle height and attitude control under some specific vehicle conditions, such as high-speed steering, and emergency obstacle avoidance, etc.