Robust control for third-order electro-mechanical systems with partially unknown dynamics under state constraints

Abstract

This work presents the design of a control trajec-tory algorithm based on Barrier Lyapunov functions (BLF) for a class of third-order electro-mechanical systems. The method considers unknown control gains and uncertain plant parame-ters, a common problem in control engineering applications. In order to deal with the uncertain parameters, this study proposes a backstepping adaptive strategy applying Nussbaum functions to know the sign of the control gains. The BLF imposes partial constraints to keep the trajectories of the system inside a safe operation set. The proposed controller is tested in a virtual one-link robotic manipulator including actuator dynamics to develop an adequate trajectory tracking. The maximum tracking error norm was 0.02, which fulfilled the maximum constrained bound of 0.5.