The AMP-Foot 2.0: Mimicking intact ankle behavior with a powered transtibial prosthesis

Almost all of the transtibial prostheses that are available on the market are purely passive devices. They store energy in an elastic element at the beginning of a step and release it at the end in order to move the body forward. The main problem with these prostheses is that only the energy that has been stored in the elastic element is used for the push-off, unlike for non-pathological ankles where the muscles provide extra energy. There are a few prostheses who use active components for this energy input. In this article, the authors propose a new design of an energy efficient, powered transtibial prosthesis to mimic intact ankle behaviour, the AMP-Foot 2.0. The main idea behind our research is to have the actuator work longer with a lower power rating while the produced energy is stored in elastic elements and released when needed for propulsion. The device is designed to provide 100% of push-off for a 75 kg subject walking at normal cadence on ground level.