Robust nonlinear control design of a robot arm with micro-hand using operator approach

Abstract

This work focuses on a robust nonlinear control design of a robot arm with micro-hand by using operator approach. In proposed control system, we can control the endpoint position of robot arm and obtain the desired force of micro-hand to perform a task, and a miniature pneumatic curling soft actuator which can generate bidirectional curling motions in different positive and negative pressures is used to develop the fingers of micro-hand. In detail, to control successively the precise position of robot arm and the desired force of three fingers according to the external environment or task involved, this paper proposes a double-loop feedback control architecture using operator-based robust right coprime factorization approach. First, the innerloop feedback control scheme is designed to control the angular position of the robot arm, the operator controllers and the tracking controller are designed, and the robust stability and tracking conditions are derived. Second, the complex stable innerloop and micro-hand with three fingers are viewed as two right factorizations separately, a robust control scheme using operator-based robust right coprime factorization approach is presented to control the fingers forces, and the robust tracking conditions are also discussed. Finally, the effectiveness of the proposed control system is verified by experimental and simulation results.