Ankle-knee prosthesis with powered ankle and energy transfer development of the CYBERLEGs Alpha-Prototype

Active prostheses have recently come onto the market, but are limited to modular forms without connections between the knee and ankle modules. Here we present the simulation, design, and preliminary data of a new knee-ankle prosthesis with an actuated ankle based on a variable stiffness actuator with energy transfer from the knee to the ankle as a part of the CYBERLEGs FP7-ICT project. The CYBERLEGs α-Prosthesis utilizes a novel active ankle joint architecture and energy transfer mechanism to transfer energy from the knee joint to the ankle. The device is capable of producing a level ground walking gait that closely approximates the joint torques and kinematics of a non-amputee while while maintaining compliant joints, which has the potential to decrease impulse losses, and ultimately reduce the end user energy consumption. This first prototype consists of a passive knee and an active ankle, which are energetically coupled to reduce the total power consumption of the device.