Super-Twisting Sliding Modes Tracking Control of a Nonholonomic Wheeled Mobile Robot

In this work a cascade robust tracking control for a nonholonomic wheeled mobile robot (WMR) is addressed, which is composed by an inverse dynamic control in the internal loop; and a robust kinematic control based in sliding modes control (SMC) techniques in the external loop. Even that invariance principle is inherent characteristic of the SMC, which assures robustness, the implementation of some SMC can be deteriorated by the so called chattering phenomenon, caused by presence of unmodeled dynamics, which effects can be worst if there is control saturation. Analysis results considering a realistic model of the WMR show that this is the case when a first order sliding modes control is applied to our framework. To circumvent the problem a robust kinematic control is proposed based on the super-twisting sliding modes control, which is a continuous second order sliding mode with a simple control algorithm.