Car transportation system grasping two drive wheels

This article describes the concept of a novel car transportation system including two mobile robots with a lift mechanism for single wheel. The system lifts only two drive wheels of a front-wheel-drive vehicle or a rear-wheel-drive vehicle, and transports them. However, the system has nonholonomic constraints because all wheels of a vehicle are not lifted by the system. This article also describes a motion control method and a vehicle´s wheelbase estimate algorithm for the proposed system in order to maneuver the vehicle. The motion control method is based on control theory for a three-wheeled cycle system. On the other hand, the vehicle´s wheelbase estimate algorithm includes impedance control, and the system estimates the vehicle´s wheelbase from constraint forces during transporting the vehicle. Finally, two experiments show that the proposed system can maneuver the vehicle.