Adaptive control method for a walking support machine considering center-of-gravity shifts and load changes

In previous studies, an omni-directional walking support machine has been developed for people suffering from walking impairment. During walking support, the machine can identify the user's directional intention according to the user's forearm pressures and support the user to where they want to go. However, the motion performance of the machine is affected by the center-of-gravity (COG) shifts and load changes caused by users, which may cause the danger of colliding obstacles. To address these issues, this paper proposes an adaptive controller for the walking support machine. This control method does not need the exact values of the plant parameters and can adapt to parameter uncertainties by measuring and adjusting the parameters automatically. Therefore, it is very robust to plant parameter changes caused by the COG shifts and load changes. Simulations are executed and the results demonstrate the feasibility and effectiveness of the proposed adaptive control method.