Control of suspensions for vehicles with flexible bodies .1. Active suspensions

In this paper, two classes of control strategies for active suspension are developed. The purpose of control is to reduce structural vibrations of the body without compromising traditional control objectives. In the first approach, the control laws for the suspension forces are synthesized to enhance modal damping in the structural modes. In the second approach, a separate proof-mass actuator mounted on the vehicle body is used to suppress structural vibrations, while suspension controllers based on a rigid-body model are utilized. The results of simulation demonstrate that with both methods significant reductions in structural vibrations can be achieved without sacrificing other aspects of performance, provided that modal variables for the body beaming modes are available for feedback. To simplify the implementation suboptimal decentralized controllers using state and subsequently output feedback are developed, which are obtained by taking advantage of the separation between the natural frequencies of the rigid-body and the structural modes. For both control methods, output feedback, including the modal variables for the body beaming modes, results in performances that are close to those obtained for a full state feedback.