Abstract
In this article, a new car transportation system which consists of two MRWheels (a Mobile Robot for a Wheel) is proposed. The system grasps only two front wheels of a front-wheel-drive vehicle and positions it. Therefore, it is possible that the system make smaller than the previous car transportation systems using multiple robots. However, the system has nonholonomic constraints because rear wheels of the vehicle are not lifted by the system. And it is necessary to transport vehicles that the system lifting front wheels knows their rear wheels' position. Therefore, to transport the vehicle, a motion control algorithm for the system and a vehicle's wheelbase estimate algorithm by mechanical interaction are proposed. First, a motion control algorithm based on the chained system is illustrated. Next, the system is applied Impedance Control to achieve the passive motion along its nonholonomic constraints when it doesn't know the vehicle's size. After that, the wheelbase estimate algorithm based on Impedance Control and its convergence are described. Finally, through preliminary experiments, the concept of the system is illustrated and the effectiveness of proposed algorithm is confirmed.
