A new filtering for uncertainty systems

A new filtering problem for discrete time system with norm bounded structured uncertainty is considered in this paper. A filter for structured uncertainty system is designed under the unbiased condition such that the filtering error system is asymptotically stable and the H_∞ norm of the transfer function of error system is minimized or less than a positive scalar γ. Sufficient condition of existence for a less conservative filter is proposed. It compensates the conservatism caused by applying the unbiased condition. Numerical example is provided to demonstrate the feasibility of the proposed condition and filter design procedure.