Simultaneous realization of power assist and skill assist for sinusoidal motions by using semi-active assist mechanism

In recent years, workers decline has become a major problem in the field such as nursing care, welfare and heavy transport work in a factory with hard work. The authors have developed semi-active assist mechanisms and their control methods as wearable power assist devices for fatigue reduction. The mechanisms have elastic material as the source of assist force, and actuators for controlling the elastic force. Elastic materials such as springs retain equilibrium because their material generates the restoring force toward a natural length. This characteristic is effective in assisting movement that requires a restoration of posture, such as bending and stretching of human limbs. We have optimized its controls for various forms of target work, and confirmed its effectiveness regarding work with a bending motion that requires a postural restoring force. Then the purpose of this study is to develop a control method of the semi-active assist mechanisms. Moreover, this study aims the simultaneous realization of power assist and skill assist based on energy control and its application to semi-active assist mechanism. The proposed skill assist method is implemented using our previous power assist device, so the device provides not only a power assist effect but also a skill assist effect to correct motion. Hence, an operator obtains both power and skill assist effects simultaneously. In order to realize power assist and skill assist simultaneously, we develop efficiency control methods between the power assist and the skill assist in this study. Moreover, to apply the semi-active assist mechanism to real-world tasks like rehabilitation, we aim to develop a control method which has effects of both motion correction and fatigue reduction.