Navigation and Motors Control of a Differential Drive Mobile Robot

Abstract

A differential drive Wheeled Mobile Robot has two independently driven wheels mounted on a common axis. Each wheel is coaxial with a Permanent Magnet Synchronous Motor. Such robot could be used for load handling or for the development of more complex robots. A simpler mechanical structure of the robot was chosen, trading it with a more complex control algorithm. This paper proposes a hierarchical approach for the navigation and motors control: (1) the higher level computes the traiectory and defines the linear and angular velocity of the whole robot; (2) the lower level computes the torque currents for the PMSM wheel motors. A dead-reckoning module reconstructs the actual space position and orientation of the robot and it is necessary as a feedback to the navigation level algorithm. Furthermore, a simple way to calculate the maximum applicable torques to prevent slippage of the wheels (no-slip conditions) is presented.