Development of a walking assistance apparatus using a spatial parallel link mechanism and evaluation of muscle activity

Abstract

A prototype for a walking assistance apparatus for the elderly or motor palsy patients was developed, using a novel spatial parallel link mechanism. The flat steps of the apparatus move in parallel with the ground; the apparatus can support entire leg alignment (including soles) and assist; walking behavior at ankle, knee and hip joints simultaneously. By using a flexible link, constructed of stainless steel and rubber, the apparatus can realize the natural twisting motions of the ankle. Furthermore, in order to assist walking on uneven surfaces, we investigated walking on a slopes or stairs. For these tasks, the apparatus was equipped with a gyro sensor and an ultrasonic sensor; so the angle of the slope and the height of the stairs could be recognized. The apparatus adapted according to the signals from these sensors. Results owed that our experiment, the equipped person wearing the apparatus could walk on slopes and stairs. Motor palsy and muscle weakness patients can walk by themselves by using the apparatus; patients who have ambulation difficulty can use the apparatus with weight bearing lift that we developed. Using the apparatus with the weight bearing lift prevents stumbling and enables input of walking movement to the brain motor area. It may be beneficial for rehabilitation to use the apparatus with the weight bearing lift. This newly developed system may facilitate motor palsy and muscle weakness patients in the rehabilitation program. The effectiveness of the apparatus for one hour walking was evaluated by variation of Mean Power Frequency (MPF) of the Electromyography (EMG) data with continuous wavelet analysis. Muscle fatigue of the Tibialis Anterior muscle (TA) decreased during wearing of the apparatus. We showed the effectiveness of using the apparatus in walking.