The evaluation of an active soft waist exoskeleton for repetitive lifting task

This study is to determine how a lightweight active soft waist exoskeleton (ASWE) reduces the oxygen consumption and activity of lower back muscles of the wearer performing the repetitive lifting tasks. The heavy and frequent manual lifting operations are usually associated with an increased risk of injury in the industry. An ASWE is designed to assist workers' spine for lifting weights. The structural composition and operation principle were described for the ASWE. Twelve men were recruited in the experiments as the test subjects. Oxygen consumption and electromyography of the thoracic erector spinae (TES) at the T9 level and lumbar erector spinae (LES) at the L3 level were recorded during 90 lifts in 15 min. Subjects' discomfort and effectiveness evaluation were collected after lifting trials. The average value of oxygen consumption was decreased from form 15.9 ml/kg/min (Without-ASWE condition) to 13.7 ml/kg/min (With-ASWE condition). The increase in electromyography root mean square amplitude from the start until the end of the lifting trial was significantly lower when the ASWE was in use for the TES (162.79 vs. 82.08%) and the LES (122.48 vs. 83.87%). The use of the ASWE showed less oxygen consumption and back muscle contraction compared to the nonuse, which might reduce metabolic consumption or slow down the muscle fatigue level of the wearer's back across the lifting trial. Therefore, wearing the ASWE can reduce the discomfort of body parts, lumbar regions that exercise for a long time.