A Decoupling 2-DoF Control Design for Lightweight Two-Link Robots

Abstract

This paper proposes a novel 2-Degree-of-Freedom (2-DoF) control system with decoupling compensators that remove interactions between axes of a lightweight two-link robot. The robot is modeled as a pair of coupled two-mass systems, and additional compensators are then applied to decouple the links, i.e. make the controlled object become two uncoupled systems. Afterwards, 2-DoF cascade control systems are constructed for the new decoupled plants, where feedforward (FF) compensators are designed based on coprime factorization method. In addition, the controller parameters are automatically varied to match with the robot's posture. The effectiveness of the proposed design has been verified through experiments with different motions of a prototype.