Dynamic model and control structure for an autonomous wheelchair

This paper presents a parameterized dynamic model of an autonomous wheelchair and proposes a control structure based on that model. Such a structure is a cascade one, where the first controller considers the kinematics of the vehicle while the second one takes into account the dynamics of the wheelchair. Asymptotic stability is proved for each controller of the cascade structure, thus assuring that all structure is stable. Specifically speaking, it is considered a kinematic controller for trajectory tracking, besides a dynamic controller that includes parameter updating. A reference trajectory supposedly free of obstacles is generated from the information about the navigating environment and the current localization of the wheelchair. A tangential obstacle avoidance controller is added to the kinematic controller without affecting its stability, so that obstacles not foreseen during the reference generation can be avoided by the autonomous wheelchair when navigating. Finally, simulation results showing the good performance of the proposed system are presented.