tailieunhanh - Hybrid Control Design for a Wheeled Mobile Robot

Abstract. We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. Under normal driving conditions, a nonlinear trajectory tracking feedback control law based on dynamic feedback linearization is su cient to stabilize the system and ensure asymptotically stable tracking. Transitions to other modes are derived systematically from this model, whenever the con guration space of the controlled system has some fundamental singular points. The stability of the hybrid control. | Hybrid Control Design for a Wheeled Mobile Robot Thomas Bak1 Jan Bendtsen1 and Anders p. Ravn2 1 Department of Control Engineering Aalborg University Fredrik Bajers Vej 7C DK-9220 Aalborg Denmark tb dimonj@ 2 Department of Computer Science Aalborg University Fredrik Bajers Vej 7E DK-9220 Aalborg Denmark apr@ Abstract. We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling no-slip constraints. Under normal driving conditions a nonlinear trajectory tracking feedback control law based on dynamic feedback linearization is sufficient to stabilize the system and ensure asymptotically stable tracking. Transitions to other modes are derived systematically from this model whenever the configuration space of the controlled system has some fundamental singular points. The stability of the hybrid control scheme is finally analyzed using Lyapunov-like arguments. 1 Introduction Wheeled mobile robots is an active research area with promising new application domains. Mobile robots are mechanical systems characterized by challenging nonintegrable constraints on the velocities which have led to numerous interesting path tracking control solutions see 16 13 4 and the recent survey of non-holonomic control problems in 11 . Recently 3 and 1 have addressed the robot path tracking problem from a hybrid systems perspective. In this paper we consider a problem of similar complexity and develop a systematic approach to derivation of a hybrid automaton and to stability analysis. Our work is motivated by a project currently in progress where an autonomous four-wheel driven four-wheel steered robot Figure 1 is being developed. The project needs a robot that is able to survey an agricultural held autonomously. The vehicle has to navigate to certain waypoints where measurements of the crop and weed density are .