Development of Powered Knee Prosthesis with Small-Scale, Light-Weight, and Affordable Series-Elastic Actuator, and its Preliminary Walking Test

Powered knee prosthesis improves locomotion of above-knee amputees by generating net positive mechanical work at the knee joint which is especially required for movements with active knee extension and flexion such as sit-to-stand maneuvers, level-ground walking with various walking speed, stair/slope ascent ambulation and so forth. However, powered prosthesis is composed of a large number of mechanical and electrical components becoming more bulky, heavy-weight and expensive than traditional passive and quasi passive prosthesis. In this study, a powered knee prosthesis with small-scale, light-weight and affordable series elastic actuator (PKP-SEA) is developed and tested on one above knee amputee. He walks on a treadmill at walking speed of 0.8m/s on the PKP-SEA and a conventional knee prosthesis and knee joint biomechanics is analyzed. As a result, the PKP-SEA shows capability of torque control for natural walking gait by imitating damper and spring function like a conventional prosthetic knee joint.