A Conversion of a Cooperative Transportation System with Two Car-Like Mobile Robots into Two-Chain, Single-Generator Chained Form and its Steering

This paper presents a novel methodology for steering a cooperative transportation system comprising two car-like mobile robots coupled together via a carrier. The system is a three-input seven-variable drift-free nonholonomic mechanical system. The three control inputs are the moving velocity of the first mobile robot and the steering angular velocities of the two mobile robots. The seven variables are the positions of the first mobile robot along the x- and y-axes, its steering angle, its orientation, the orientation of the carrier, the steering angle of the second mobile robot, and its orientation. We first convert the system into two-chain, single-generator chained form, based on differential geometry. We secondly present a control method of the system with polynomial inputs derived in chained form. Validity of the conversion and the control method is verified by computer simulations performed on driving this cooperative transportation system into a garage.