Actuator requirements for an active suspension to prevent two-wheel lift-off in a severe manoeuvre

Abstract

The force requirements and control laws for an actuator forming a part of an active suspension are derived using the framework of optimal control theory. Prevention of two wheel lift-off during a severe fish-hook manoeuvre is identified as the critical performance requirement for the actuator. The equations of motion of the vehicle equipped with the active system are used to formulate an optimal control problem with constraints on the suspension motion and various design considerations taken as objective functions. Solution of the optimal control problem yields time-dependent active suspension forces to be applied to prevent two-wheel lift-off and thus improve its road-holding capability. The influence of actuation modes, force constraints, actuator response characteristics, etc. on the nature of active force variation is studied and system level control strategies are developed.