Robust adaptive control with a reduced order controller

The adaptive control of a stable plant with a ROC (reduced-order controller) which is marginally stable is addressed. The ROC is obtained from a ROM (reduced-order model) of the plant, which approximates the frequency response of the estimated plant. The ROC which stabilizes both the ROM and the estimated plant is designed by the pole placement scheme with some modification in order to satisfy the specifications on the gain and phase margins of the overall system. The proposed adaptive control algorithm takes the gain and phase margins into consideration in the design process to increase the robustness of the control. Simulation results show that the proposed algorithm is more robust than previous algorithms