A switching action for PID controller to improve trajectory tracking performance

PID controllers are widely used in various application fields. The desired control performance for a nonlinear system cannot be obtained easily because of the difficulty of the gain selection for PID controllers. To improve the control performance of a PID controller, we present a switching action for taking advantage of the robustness of SMC and keeping the simplicity of the PID controller. For the switching action, we first define the desired error dynamics of PID controllers and then define a sliding surface that is matched to the desired error dynamics: the derivative of the sliding surface is equal to the desired error dynamics. We suggest an existing systematic gain selection method for the PID controller and switching action. The stability of the proposed method is verified using the Lyapunov function and a stable condition of the proposed method is also evaluated. The effectiveness of the switching action is shown through a simulation on a linear system, and an experiment on a nonlinear system of varying inertia.