Adaptive LQG control of positive real systems

An adaptive control law for PR plants is proposed. The main feature of this approach is that the role of adaptation is not to stabilize the plant but to improve performance. The plant is identified using a standard Least Squares algorithm and through a suitably defined parameter modification, the plant estimates are constrained to a region in the parameter space corresponding to Positive Real Observable Controllable plants. Using these estimates an LQG disipative controller is designed which trivialy stabilizes the plant. Simulation results are presented.