An experimental comparison between Q-parameterization, H∞ synthesis and servo control systems designs

We compare three different methods of control system design for controlling dynamical systems: Q-parameterization theory, H_∞ synthesis and servo control system design. The three controllers are designed such that the robustness and performance goals are satisfied and the system response has the same settling time in all three designs. A two degree-of-freedom magnetic micro-levitation positioner is used for the discussion. We show theoretically and experimentally that with modern robust control, Q-parameterization and H_∞ synthesis, one can achieve robust stability and robust performance, while with the servo control, it is difficult to achieve these goals. We also show that, with the Q-parameterization theory we can obtain a controller of lower order than the H_∞ controller and achieve the robust stability and performance goals. Several experiments were performed on the system with the three different controllers.