The Ankle Mimicking Prosthetic Foot 3 - Locking mechanisms, actuator design, control and experiments with an amputee

The Ankle Mimicking Prosthetic Foot 3 is an energy efficient bionic foot using the principle of optimal power distribution. The main challenge behind this research is focussed on retrieving as much energy as possible from the gait and to incorporate an electric actuator with minimized power consumption. The Ankle Mimicking Prosthetic (AMP-) Foot 2, as a proof-of-concept, showed the advantage of using the Explosive Elastic Actuator capable of delivering the full ankle torques (±120Nm) and power (±250W ) with only a 60W motor. The novelty of this work is focussend on the addition of an extra locking mechanism to the AMP-Foot 3 which bring additional assets such as natural adaptability to different walking speeds and slopes and an improved energy storage during early stance implying a greater reduction of the power requirements of the motor to only 50W while still being able to produce the peak output torque and power necessary for walking. In this article, the authors present the AMP-Foot 3 focussing on its critical mechanical parts, its actuation design and its control. Experiments with an amputee are also presented to show its effectiveness.