Abstract
In this paper, we conducted theoretical investigation and experimental verification of robustness on a power assist system that utilizes stiffness optimization of a mechanical elastic element. This power assist system amplifies torque of its operator and optimizes the stiffness automatically to minimize torque of an actuator in the case of sinusoidal motions. The theoretical investigation clarified physical meanings of all terms of the controller, which realizes the torque amplification and the automatic stiffness optimization. Some experimental results demonstrated the effectiveness of the proposed power assist system even when some physical parameters of the controlled object are not known precisely.
