Optimal ℋ ∞ control for electromagnetic suspension systems with finite frequency specifications

In this paper, the problem of ℋ ∞ control for electromagnetic suspension (EMS) systems is addressed, and cases of both finite and entire frequency are discussed. Firstly a linear state-space model is applied to approximated the complex EMS system, and then ℋ ∞ performance index is adopted to measure ride comfort in circumstance of more general exogenous disturbances. By using the generalized Kalman-Yakubovich-Popov (KYP) lemma, the entire frequency ℋ ∞ norm is extended to finite frequency case. Consequently, for concerned frequency range, the ℋ ∞ performance of EMS system can be further improved. Finally, numerical simulation on an EMS system is performed to validate the effectiveness of the proposed approach.