Abstract
The aim of this study is to determine the optimum position and orientation of vertical handrail for the sit-to-stand (STS) movement frequently performed by humans. Twelve university students participated, and eight electromyograms (EMGs), namely, the brachioradialis, flexor carpi ulnaris, extensor carpi radialis longus, latissimus dorsi, right and left rectus femoris, and right and left tibialis anterior, were recorded. Observations with vertical handrails at various tilt angles and forward distances from the edge of seat were analyzed for the optimization. The total physical load (TPL) function was formulated as the weighted sum of the EMGs. The result shows that the handrail installation position has significant effects on all the EMGs except the right and left rectus femoris. The weight coefficients of the TPL function are active for the upper limb muscles. The handrail position for multiple users was formulated to minimize the TPL function, and hence the optimum position was determined.
