IEEE Transactions on Automatic Control, Vol.60, No.11, 3119-3120, 2015
Comment on "Further Enhancement on Robust H-infinity Control Design for Discrete-Time Singular Systems"
In the above paper, a robust H-infinity control design method was presented for uncertain discrete-time singular systems, which was formulated in terms of bilinear matrix inequalities and claimed to be necessary and sufficient. In this note, it is shown that the necessity of Theorem 4 in the above paper and its consequences do not hold. Then, the robust H-infinity control design method in the above paper is only sufficient. It is also noted here that conditions in the rest of the above paper are necessary and sufficient.
Keywords:Bilinear matrix inequality;discrete-time systems;robust H infinity control;singular systems