Passivity-based Tracking Control of an Omnidirectional Mobile Robot Using Only One Geometrical Parameter

This paper presents an output feedback tracking control scheme for a three-wheeled omnidirectional mobile robot, based on passivity property and a modified generalized proportional integral (GPI) observer. The proposed control approach is practical from an implementation point of view, since only robot position information and one robot geometrical parameter (i.e., contact radius) are required. Firstly, a dynamic model is given and passivity property is analyzed. Then the controller is designed based on passivity property and a modified GPI observer. The design objective is to preserve the passivity property in the closed-loop system, which is conceptually different from the traditional control design methodology. Particularly, the designed control system takes full advantage of the robot natural damping forces. Therefore, only considerably small or non-differential feedback is needed. In addition, theoretical analysis is given to show the closed-loop stability behavior. Finally, experiments are conducted to validate the effectiveness of the proposed control system design in both tracking accuracy and robustness.