Development of an easy-to-manipulate assistive cart system using an observer based impedance control

In this paper, we develop an assistive cart that allows users to transport heavy load with lower effort. Our focus is placed on how to design and control the assistive cart to provide reliable user-cart interactions regardless of the condition changes of the loaded weight and the ground. For this purpose, Force/Torque sensor and two motorized wheels are equipped on a conventional cart to response to the user´s operation by sensing the input force and generating the assist force. The observer-based impedance control is designed to compute the assistive force with the input force of the user and the velocity of the cart. We verify the validity of the developed assistive cart by comparing the performance of the empty-cart case and the loaded-cart case.