Motion-tracking skill assist and power assist for sinusoidal motions with a semi-active assist mechanism using energy control

This paper describes a skill assist method for sinusoidal motions using a semi-active assist mechanism through an energy control method. In a previous study, we had developed and verified the effectiveness of a power assist device with a semi-active assist mechanism and a control method for reducing loads during periodic motion. Here, we have developed a skill assist method as an extension of our power assist device for periodic motion. The skill of performing sinusoidal motions is defined in this study as an operator’s ability to track such motions. Therefore, our skill assist method attempts to improve the operator’s tracking ability. The proposed skill assist method is implemented using our previous power assist device; therefore, the device provides not only a power assist effect but also a skill assist effect to correct the motion. Hence, an operator obtains both the power and the skill assist effects simultaneously

A yank-based variable coefficient method for a low-powered semi-active power assist system

In this paper, we developed a power assist system to help users on carrying heavy loads. This system uses the user input force and position to generate an aiding force, reducing the burden on carrying heavy loads. We adopted a semi-active methodology, combining an active with a passive element, aiming to match the best traits from both, and also considering a lighter motor, which makes the system reach its limit force. To control this lightly actuated semi-active system we proposed a proportional controller which has its gain tuned accordingly to the yank value; this is calculated by the derivative of the force. The controller method herein amplifies the system response whenever the user intends to change his movement, producing a better handling of the system and saving actuator power for either periodical or non-periodical movements. Future applications may involve creating a light assist system for portable applications or assist in heavy industrial environments