On integral sliding mode control for a unicycle

Abstract

In this paper we present an integral sliding mode controller (ISMC) that can stabilise an underactuated unicycle system. The unicycle consists of a wheel and a saddle that is modelled as an inverse pendulum. The control objective for a unicycle is to achieve position control of the wheel while keeping the pendulum at the balanced position that is an unstable equilibrium. The only driving force is the torque applied to the shaft of the wheel. The proposed ISMC consists of an integral sliding surface, a switching term, a nonlinear compensation term and a LQR stabilising controller for the sliding manifold. The ISMC can effectively reject the matched disturbance and reduce the infl uence from unmatched disturbances, which is verifi ed through rigorous analysis and intensive numerical validation. Copyright © 2014 Inderscience Enterprises Ltd.