Design and Control of A Passive Mobile Robot System for Object Transportation

In this paper, we propose a concept of a passive type robot for transporting a single object in coordination with a human operator. We developed a prototype of passive type robot referred to as RT Porter, which consists of support frame, three omni-directional wheels with MR brakes, and onboard computer system. In this research, we control the brake torque of each wheel based on the brake force/moment constraint and this allows RT Porter to track a 2D path, which includes motion perpendicular to human's pushing direction without using servo motors. Experimental results are shown to illustrate the validity of the proposed concept