Individual Adjustment of Contraction Parameters for Effective Swing Assist Using a Pneumatic Artificial Muscle in the Elderly

Abstract

Leg swing during walking is controlled by hip and knee flexion motions. This study examined the effect of swing assist using a pneumatic artificial muscle (PAM) driver system on hip and knee motions and gait performance in the elderly. The participants consisted of 10 healthy elderly individuals. Two PAMs were attached to each participant’s left hip joint, and a pressure sensor was inserted under the right heel as the trigger. PAM contraction parameters could be controlled through a smartphone, i.e., the delay from trigger to contraction and the contraction duration. These parameters were randomly changed to 0, 100, or 200 ms for the delay and 100, 200, or 300 ms for the contraction. Four combination patterns of delay and contraction duration were observed as the parameter settings for maximizing the hip flexion angle. During walking with the PAM assistance, the hip and knee flexion angles in the swing phase and hip angular excursion of the elderly were significantly increased without altering the gait performance. The findings show that our PAM driver system can realize effective swing assist through changing temporal parameter settings for the PAM contraction in the elderly.