Swing up Control of the Pendubot with Restricted Actuator Movement Angle 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, considering the restricted angular movement of the shoulder joint. 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, a target trajectory of the shoulder joint is calculated such that the mechanical energy of the forearm motion increases. We design a tracking control law for the shoulder joint with respect to a target trajectory. The maximum amplitude of the target trajectory directly restricts the angular motion of the actuator. The effectiveness of the proposed method is verified by numerical simulation and actual experiments.