Active Control of Vehicle Air Cushion Suspensions

Abstract

A primitive vehicle suspension system coupling a simple vehicle model to a guideway having random irregularities is defined. The optimum linear suspension which minimizes a linear combination of vehicle heave acceleration (a passenger comfort index) and suspension-guideway displacement (a measure of required suspension stroke length) is synthesized using a Wiener- Höpf technique. This optimum suspension, which is independent of specific mechanical, magnetic, or fluid methods of implementation, is used to determine the form of active control required to make the performance of a flexible-skirted air cushion suspension approach the optimum performance. The optimally compensated suspension acceleration, flexible base, and gap height excursions are computed and compared with those of optimum passive suspensions. A reduction in acceleration by a factor of 2.7 is possible with optimum active control. Finally, the limitations and constraints in implementing both optimum and suboptimum control of an air cushion suspension were studied using a small scale experimental suspension.