Energy Regeneration From Electromagnetic Induction by Human Dynamics for Lower Extremity Robotic Prostheses

Wearable robotic devices often need electrical energy. An interesting idea is to collect mechanical energy during walking and convert it into electrical energy to recharge these devices directly. In this article, we built a light-weight robotic prosthesis (1.3 kg) with the feature of self-charging. During stance phase, the prosthetic ankle joint with damping, is driven by human dynamics. The rotated ankle joint backdrives themotor, and themotor works as a generator according to the electromagnetic induction theory. Five subjects participated in experiments to verify the feasibility and five speeds walking were studied (0.7, 0.9, 1.1, and 1.3 m/s treadmill speeds and one self-selected outdoor walking speed). Experimental results demonstrate that the electrical regenerative energy per step is 1.53 +/- 0.29 J on average. Meanwhile, an average consumed energy per step of the robotic prosthesis is 4.64 +/- 0.15 J, which means 33 +/- 5% energy can be returned to the active prosthesis (battery, 24 V, 2.6 Ah).