Intelligently Controlled Above Knee (A/K) Prosthesis

In existing advanced A/K prostheses the sti ness and damping at the prosthetic knee joint are applied by hydraulic or pneumatic cylinders. The pre-set parameters being constant, are not optimal during the whole gait cycle, for di erent walking speeds, and sudden posture irregularities. The complexity of normal and prosthetic gait leads to the development of 'soft' control (non-analytic) governed by a nite set of rules. The pre-de ned and stored parameters and rules are combined as the knowledge-base of the system. This knowledge is based on existing experience and known facts about both normal and prosthetic gait. The methodology of developing the controlled prosthesis was rst to study normal gait by modeling and simulating level human gait. Then the prosthetic gait was investigated using the normal gait model with a passive (parameter controlled) and a realizable knee joint. The results of the prosthetic gait investigation gave the values and ranges of the controlled impedance parameters, the predicted performance of the controlled prosthesis, and the moment (e ort) required from the amputee. A laboratory prototype of a controlled A/K prosthesis was built and evaluated in the clinic.