Functional Design Of A Transmission For A Myoelectric Elbow Prosthesis

Many artificial arms include myoelectric hands and passive elbows. Myoelectric elbows can profitably substitute the passive ones only if they can guarantee: durability, low noise, adequate torque, low power consumption, low weight, easy motion control and natural movements. Most of these objectives can be reached by good mechanical design of the system. Mechanical efficency of the mechanism is one of the key factors and can be achived only avoiding long chains of gears. The adoption of a serie of linkages allows to transform efficently the high speed of the engine, to the low angular velocity of the elbow. By the kinetic point of view the system of linkages has roughly to mantain a costant ratio between the above velocities. For the efficency of the transmission, angles must be always over a critical value and the links must have low momentum of inertia. This work shows the functional approach in a new designed elbow prosthesis.