Power assist for lifting motion in sagittal plane by forearm support-type lift assist system (FOLAS)

Lifting a heavy object is regarded as a frequently performed motion that imposes physical strains on workers. The objective of this study is to verify the effectiveness of forearm support-type lift assist system (FOLAS) for lifting motion in the sagittal plane. The mechanical structure of the FOLAS is largely divided into a forearm support and a parallel motion arm; the forearm support has no fixture to tie operator´s body and can supports operator´s forearm effectively while the FOLAS assists a lifting motion. The FOLAS is operated based on pneumatic pressure data in air cushions, which are attached on the forearm support and receive operator´s forearm softly. The forearm support is mounted on the 2-DOF parallel motion arm, which keeps the forearm support in a horizontal position during the FOLAS operation. Owing to these characteristics, operators can maneuver the FOLAS intuitively without fixing his/her body on the mechanical structure. A fundamental experiment and an experiment for a lifting motion in the sagittal plane were performed. The experimental resut for the lifting motion showed the muscle activation of an experimental subject was alleviated by the assistance of the FOLAS.