Cartesian motion control of a mobile robot

This paper presents the Cartesian motion control system of the autonomous mobile robot MACROBE (mobile and autonomous computer controlled robot experiment) of the Laboratory for Automatic Control Engineering, Technical University of Munich. This Cartesian motion control system is applicable to any vehicle with tricycle kinematic. It has a comfortable and open user interface and provides high path accuracy. The robot´s 2D motion path is specified by a sequence of Cartesian subgoals. In a first step, the local path planning interpolates the subgoals by a combination of line and arc segments. In a subsequent step, a path with continuous curvature is obtained through approximation of the arc segments by polar splines. Polar splines allow easy calculation of the required steering angle based on the actual vehicle posture (position and orientation) through a combination of feedforward and feedback control. The paper describes system structure, command language, controller design, and experimental results.