Effect of Contraction Parameters on Swing Support During Walking Using Wireless Pneumatic Artificial Muscle Driver: A Preliminary Study

We developed wireless pneumatic artificial muscle (PAM) driver that can control delay before contraction starts, and duration of contraction through GUI of an application running on a smartphone. The purpose of this study is to evaluate the effect of these two parameters on the joint motion in the swing phase for realizing optimal swing support. The PAMs were placed above the left hip joint in order to support the left hip flexion in the swing phase. Pressure sensor was placed under the right heel for detecting the heel contact that triggers the activation of the PAMs. Subjects walked with the support under different contraction parameters. The experimental result clearly demonstrated that the hip flexion angle in the swing phase increased in all subjects, although there was individual difference in the optimal delay between heel contact and start of the PAM contraction. In addition, the variability of the hip flexion was decreased, while the hip flexion angular velocity and the peak value of the knee flexion angle were increased by the swing support for the hip joint under the optimal delay parameter. The results of this pilot study suggested that leg swing could be instantaneously modified by the support of PAMs and the optimal parameter for realizing the most effective support differed among subjects. Our wireless PAM driver enables the most effective walking support depending on the physical ability of the patient by its functionality to adjust the contraction parameters.