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.