Three-stage computed-torque controller for trajectory tracking in non-holonomic wheeled mobile robot

Abstract

The use, design and fabrication of Wheeled Mobile Robots (WMRs) is on a surge both in industry and academia. This paper presents in detail the dynamic formulation of a non-holonomic WMR, and proposes a 3-stage controller for stable tracking - an outer controller which operates on the positioning error, an inner controller which applies PID control over the robot's velocity, and a non-linear compensator which applies inverse dynamics control to calculate motor torques. MATLAB Simulink was used to develop a model of the robot, the controller, and the trajectory generator. Simulation results showed acceptable behaviour even when random errors are introduced in the system. A physical model of the WMR was also manufactured and a Raspberry Pi microprocessor was used to test the control algorithm.