Stabilization Of Underactuated Mechanical System Using Adaptive Sliding Mode Control

Abstract

In the past decade, there has been increasing interest in underactuated mechanical systems. These systems have many practical and diverse applications in modern science and engineering. The broad application areas of underactuated systems include robotics, industry, and aerospace systems. This thesis presents a simple stabilizing control algorithm for a class of underactuated mechanical systems with n degrees of freedom (n DOF). The methodology is based on adaptive sliding mode control. Firstly, the system is transformed into a special structure through input transformation, containing nominal part plus some unknown term. The unknown term is computed adaptively. Later the transformed system is stabilized using adaptive sliding mode control. The adapted laws are derived in such a way that the time derivative of a Lyapunov function becomes strictly negative. The effectiveness of the proposed method is applied to different underactuated systems with 2 DOF and 3DOF: Inverted pendulum, TORA system, The Pendubot and Acrobot, Ball and Beam system and double inverted pendulum. Computer simulation results show the effectiveness of the proposed control algorithm on these systems.