Identification, uncertainty modeling and robust controller design for an electromechanical actuator

Abstract

Electromechanical actuators (EMAs) are of interest for applications which require easy control and high dynamics. This paper addresses the experimental identification, structured and unstructured uncertainties modeling, and robust control design for an EMA system with harmonic drive. Two robust controllers are designed by two proposed approaches: The first is based on Kharitonov theorem, which not only robustly stabilizes the uncertain EMA system but also maintains the pre-specified margins and bandwidth constraints. The second is feedback compensation design procedure based on H∞ control theory, verifying good tradeoff between the powerful H∞ controller and the unique features of feedback compensation, such as simplicity, effectiveness, low sensitivity to parameters variations, low cost, and easy implementation. Simulation and experiments prove the robustness and high tracking performance of the robust EMA systems which reveals the affectivity of the proposed robust control design methods.