Second generation approaches to active and semi-active suspension control system design

A number of `second generation' suspension controller design methods are reviewed in the context of a simple quarter-car model. The methods involve robustness and performance criteria not addressed in simple `first generation' designs, such as sky-hook damping or LQG optimal control. Three such approaches are considered in detail; these are nonlinear optimal control, control with road-surface preview, and H∞ optimal control. Potential advantages of these systems are demonstrated in a uniform framework, by comparing performance with that of a reference LQG controller, over a range of operating conditions