Abstract: A wheelchair robot equipped with variable geometry single tracked mechanisms(VGSTMs) is proposed. This mechanism can actively control the track shape and tension to adapt to the obstacles by rotating the two pairs of flippers, so it becomes possible to improve the obstacle clearing capability of the traditional wheelchair. Following a presentation of some typical mechanisms for obstacle clearing, the mechanism scheme and the stair-climbing process of the robot are introduced. With the aim of stair-climbing, the wheelchair robot is translated to a serial manipulator, base on which the geometric model that can describe the position and the track shape of the robot is established, and the optimal solution method of the driving component moment with Lagrange dynamic equations is proposed. In the simulation, the variations of the driving moment during stair-climbing are obtained, and then the design of the driving system and the mechanical structure of the robot are completed with the simulation results. The stair-climbing experiment is performed with the prototype to verify the obstacle clearing capability of the robot.

Key words: Driving moment, Obstacle clearing capability, Variable geometry single tracked mechanism, Wheelchair robot