Motion control of caster-type passive mobile robot with servo brakes

In this paper, we introduce a passive mobile robot called prototype Caster-Type Passive Robot Porter (C-PRP), which is developed on the basis of a concept of passive robotics. This mobile robot consists of two casters with servo brakes and one passive rigid wheel. Prototype C-PRP has passive dynamics with respect to the force applied by a human and controls its appropriate motion with the servo brakes. We derive the feasible braking force/moment applied to the robot on the basis of the characteristics of the servo brakes. This paper especially focuses on a fundamental motion control algorithm based on the feasible braking force/moment. We realize the path tracking function and the collision avoidance function as examples by applying the proposed algorithm to prototype C-PRP. These functions are implemented to prototype C-PRP actually, and experimental results confirm its validity.