Sufficient LMI conditions for output feedback control problems

In this paper the authors present linear matrix inequality (LMI) conditions for output feedback control problems. The results based on sufficient cond itions because they are dependent on the particular state-space representat ion used for describing the system. Nevertheless, the conditions are not se nsitive to a certain class of state-space transformations, and if the contr ol problem is feasible then there exists some state-space transformation le ading the conditions to be necessary and sufficient for the problem. The au thors approach can be used for designing decentralized controllers and is e asily extended to H-2, H-infinity and mixed H-2/H infinity problems via sta ndard LMI techniques. The continuous- and discrete-time cases are considere d and numerical examples are given to illustrate the results.