Path tracking control considering center of gravity shift and load change for an omni-directional walker

Walking is a vital exercise that is very important for health and everyday life. In the authors´ previous studies, an omni-directional walker was developed for walking rehabilitation. Walking training programs are stored in the walker so that rehabilitation can be carried out without a physical therapist. However, the walker sometimes strays from the predefined path due to a center of gravity shift and load change. It is necessary for the walker to precisely follow the paths defined in the walking training programs to guarantee the effectiveness of rehabilitation and the user´s safety. Therefore, this paper describes the path tracking control of the omni-directional walker during the center of gravity shift and load change. First, the kinetics of the omni-directional walker motion is presented. Second, an adaptive control strategy is proposed. Finally, path tracking simulations are carried out using the proposed method. The simulation results demonstrate the feasibility and effectiveness of the adaptive control method.