Nested Plant/Controller Optimization with Application to Combined Passive/Active Automotive Suspensions

1. Graduate student; 2Professor, Dept. of Mech. Eng., The University of Michigan, Ann Arbor, MI 48109-2125. 3. Principal Research Engineer, Ford Research Laboratory, Ford Motor Company, Dearborn, MI 48121. Abstract This paper addresses the coupling between the plant and control optimization problems for a suspension comprising both passive and active components. Suspension dynamics are modeled using a two degree-of-freedom, linear and time-invariant quartercar model whose ability to capture the influence of the passive stiffness on rattle space depends on the ground disturbance’s spectral density. Nested optimization, a strategy that guarantees system optimality, is presented and used to find the optimal suspension system design. The design exhibits superior performance compared to its passive, active and sequentially optimized passive/active counterparts because it accounts for the coupling between the passive and active suspension optimization problems.