Motion control of passive mobile robot with multiple casters based on feasible braking force and moment

We introduce a passive mobile robot called CPRP (Caster-type Passive Robot Porter). This robot consists of multiple casters with servo brakes and a controller. C-PRP employs passive dynamics with respect to the force applied by a human. Its appropriate motion is controlled using the servo brakes. In this paper, we derive and analyze a feasible braking force/moment that can be applied to the robot on the basis of the characteristics of the servo brakes. In addition, we propose a motion control algorithm for C-PRP based on the analysis of this feasible braking force/moment. This algorithm is independent of the number of casters. The proposed algorithm is applied to a four-wheeled C-PRP and the experimental results confirm its validity.