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- Ho¨pf 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.