Digital control design for an IPMC actuator using adaptive optimal proportional integral plus method: Simulation and experimental study

In this paper, the application of a novel digital control method, called adaptive optimal proportionalintegral-plus (AOPIP), to beam-like ionic polymer-metal composite (IPMC) actuators is investigated. First, as a gray-box system, the dynamical model of the IMPC cantilevers is obtained and then AOPIP method is derived and applied to several IPMCs with different physical properties to evaluate the efficacy of the control method. Basically, AOPIP is a proportional-integral-plus (PIP) controller with two additional terms; an optimal gain tuner mechanism with means of linear quadratic regulator (LQR) method and an adaptation term based on recursive least square (RLS) method with Kalman filter (KF), RLS-KF. Therefore, the main advantages of this controller are a) independence of parameters of the system; and b) an optimal performance. To perform a comparative study, in addition to AOPIP, a digital PID controller is designed and applied to the system in simulation. Besides, the comparison of opened-loop techniques to closed-loop ones is investigated as well. Furthermore, an experimental test for comparing AOPIP and digital PID is performed to show the performance of the IPMC in real-time, and under real conditions such as existence of external noise and disturbances. Using several proper numerical indicators, both simulation and experimental results demonstrate the efficacy of the AOPIP and its superiority to the opened-loop techniques and digital PID controller in terms of control effort, desired tracking precision of the IPMCs actuators and its optimality. (C) 2019 Elsevier B.V. All rights reserved.