Nonlinear Control System Design of an Underactuated Robot Based on Operator Theory and Isomorphism Scheme

Abstract

The number of actuators of an underactuated robot is less than its degree of freedom. In other words, underactuated robots can be designed with fewer actuators than fully actuated ones. Although an underactuated robot is more complex than a fully actuated robot, it has many advantages, such as energy, material, and space saving. Therefore, it has high research value in both control theory and practical applications. Swing-up is a mechanism with two links, which mimics a gymnast performing a horizontal bar movement. Over the past few decades, many sufficiently robust control techniques have been developed for a fully actuated robot but almost none of them can be directly applicable to an underactuated robot system. The reason is that such control techniques require certain assumptions that are valid only for fully actuated robot systems but not for underactuated ones. In this paper, a control system design method for underactuated robots based on operator theory and an isomorphism scheme is first proposed. Bezout identity is designed using isomorphism. The effectiveness of the design method is confirmed by simulation. The simulation results show that the performances, such as robust stability and response time, of an underactuated robot control system are improved.

Motion Planning of Differentially Flat Planar Underactuated Robots

“…The first class includes machine tools and robots, and the second class includes vibrating systems excited by base motion, unbalance, wind, and other physical phenomena. Underactuated mechanical systems are less common and have more DOFs than actuators [1,2]. In recent years, the interest in underactuated systems has increased in the field of robotics [3][4][5] and legged locomotion [6,7].…”

Evaluation of Linearization Methods for Control of the Pendubot

“…The considered topics also cover essential aspects related to under-actuated robots, which are constantly being developed, bringing new values or detailing the problem of control of such systems [12][13][14].…”