Dimitris P. Tsakiris
Nonholonomic Visual Servoing
Visual servoing is a class of sensor-based control strategies, which have been successfully used for manipulator arms equipped with vision sensors. We are interested in extending these strategies to nonholonomic mobile manipulators, namely mobile robots carrying a hand-eye system and subject to nonholonomic motion constraints. We are also interested in studying the effect that mobility restrictions have on the tasks that an active observer is able to accomplish. In particular, we consider the vision-based stabilization of a mobile manipulator to a desired pose with respect to a target of interest. Instances of this problem occur in practice during docking and parallel parking maneuvers of these vehicles. Our approach involves the use of continuous time-varying state feedback control laws to stabilize the nonholonomic mobile base to its desired pose. The state feedback uses visual data obtained from the camera mounted on the manipulator arm, which tracks continuously the target as the base moves. The experimental evaluation of the proposed techniques employs a mobile manipulator prototype developed in our laboratory and dedicated multiprocessor real-time image processing and control systems.