Swing up Control of the Pendubot with Elbow Joint Extended Using Energy-Based Methods

Abstract

In this paper, we propose a swing-up control law for the Pendubot, a type of two-joint, two-link, underactuated robot in which the shoulder joint is actuated and the elbow joint is unactuated, maintaining the elbow joint fully extended as much as possible. The proposed control law is designed by the energy-based method. Using the phase plane trajectories obtained from the angular and angular velocity oscillatory motion of the forearm, the target trajectory of the shoulder joint is calculated so that the trajectory is a small phase advance from the forearm. We design a tracking control law for the shoulder joint so that the forearm and the upper arm behave as a single pendulum. The effectiveness of the proposed method is verified by numerical simulation and actual experiments.