Abstract:
Naturally, the human ankle is capable of providing enough net positive work during walking, and therefore enables a normal human to propel forward. For a trans-tibial amputee, unlike the natural arrangement, the passive ankle-foot prosthesis is not capable of any such thing, and therefore it cannot aid or restore the natural gait in any way.
To enable the amputee to walk again, in a natural gait, a prosthesis capable of doing net positive work is required. The need for such powered prosthesis has been recognized due to the research on this matter but only one group of scientists so far has successfully developed and maintained that such a device which enables an amputee to have a natural walking gait. The main challenge in developing such prosthesis is to make it comparable to the actual human weight and size, and still be able to provide enough torque and power in order to follow the natural gait for a normal human.
Our work presents the design of mechanical components and their control for the working of a motorized ankle-foot prosthetic device which is capable of doing net positive work thus enabling the amputee to follow a natural walking gait. The basic model has a spring connected in parallel with a Series Elastic Actuator. The spring used is a unidirectional spring. The entire assembly approximates the normal human ankle size and weight and can provide enough torque and power in order to mimic normal human walking behavior. A control scheme is implemented to enable the prosthetic to follow the normal human gait.
