Adjusting Ankle Angle Measurement Based on a Strain Gauge Bridge for Powered Transtibial Prosthesis

Abstract

Inaccurate ankle angle measurement may affect gait event detection accuracy, control parameter precision and assessment validity, and even finally result in gait asymmetry. This paper proposed an adjustment method based on a strain gauge bridge to obtain accurate ankle joint angle measurement for a powered transtibial prosthesis. The characteristics of relative creep, hysteresis, and temperature were studied. Then the curving fitting was used to study the relationship between the measured value of the strain gauge bridge and the compensation angle. Three male transtibial amputees participated in the experiments. Experimental results show that the strain gauge bridge can sense the deformation of carbon-fiber footplate, and be utilized to adjust the ankle angle. The effects of an inaccurate ankle angle were further discussed.