Abstract
This paper investigates the problem of H-infinity control for active seat suspension systems via dynamic output feedback control. A vertical vibration model of human body is introduced in order to make the modeling of seat suspension systems more precise. Meantime, different from the existing H-infinity control methods which conduct disturbance attenuation within the entire frequency domain, this paper addresses the problem of H-infinity control for active seat suspension systems in finite frequency domain to match the characteristics of the human body. By using the generalized Kalman-Yakubovich-Popov (KYP) lemma, the H-infinity norm from the disturbance to the controlled output is decreased over the chosen frequency band between which the human body is extremely sensitive to the vibration, to improve the ride comfort. Considering a practical situation of active seat suspension systems, a dynamic output feedback controller of order equal to the plant is designed, where an effective multiplier expansion is used to convert the controller design to a convex optimization problem. Compared with the entire frequency approach for active seat suspension systems, the finite frequency approach achieves better disturbance attenuation for the concerned frequency range, while the performance constraint is guaranteed in the controller design, which is verified by a practical example with certain and random road disturbances. (C) 2010 Elsevier Ltd. All rights reserved.