Path planning and guidance techniques for an autonomous mobile cleaning robot

In the past mobile robot research was often focused on various kinds of point-to-point transportation tasks. Mobile robot application in service tasks, however, requires quite different path planning and guidance approaches. This paper introduces and discusses in detail specific planning and guidance techniques for a mobile floor-cleaning robot. A kinematic and geometric model of the robot and the cleaning units as well as a 2D-map of the indoor environment are used for planning an appropriate cleaning path. The path is represented by a concatenation of two kinds of typical motion patterns. Each pattern is defined by a sequence of discrete cartesian intermediate goal frames. These frames represent position and orientation of the vehicle and must be translated into motion commands for the robot. The steps of this semi-automatic path planning system are illustrated by a typical cleaning environment. Vehicle guidance includes execution of the planned motion commands, estimation of the robot location, path tracking, as well as detection of and reaction to (isolated) obstacles. For location estimation a least-squares fitting of corresponding geometric contours from the 2D-environment map and geometric 2D-sensor data is used. Obstacle detection is accomplished by testing geometric 2D-sensor data to be part of the preplanned cleaning path. Path planning and parts of the developed vehicle guidance system have been tested with the experimental mobile robot MACROBE. Results reported in this paper demonstrate the efficiency of the described planning, location estimation and path tracking procedures in basic floor-cleaning tasks