A Comparison of ℋ∞-Synthesis and Feedback Linearization for Rotary Inverted Pendulum

This paper investigates the performance comparison of ℋ ∞ based control and feedback linearization. The comparison is conducted on a challenging rotary inverted pendulum (RIP) system. The main difficulty of controlling RIP is the existence of RHP poles and zeros. Since the plant does not satisfy the typical ℋ ∞ control design conditions, a transformation of the location of RHP zeros is employed which put the system in a desired/solvable form. The existence of unstable internal dynamic states also causes some problems in the design of feedback linearization. These problems is solved by employing an outer loop cascade control scheme. The theoretical backgrounds and the design steps for the specific problem are listed. The designed controllers are tested on the nonlinear model whose parameters are perturbed to test the robustness of the controllers. The results of the Monte Carlo simulations are presented and findings are discussed.