Unpowered Knee Exoskeleton during Stair Descent

This study developed an unpowered knee exoskeleton which used the custom-built spiral spring to convert negative work to assist knee extension during stair descent. The optimization of the function angle and the stiffness of spiral spring were conducted to get the optimal parameters. Six healthy participants descended the fix-steps stair with and without the prototype, while the rectus femoris (RF) and biceps femoris (BF) as selected muscle were recorded the sEMG signal. Results show that the average mean normalized sEMG signals of RF were reduced by 6.12%-13.54%. The use of an unpowered bilateral exoskeleton that stores and returns moment in parallel with the knee to reduce the extensor muscle activation during SD. Future works are needed to verify the effectiveness of the compliant joint.