Inverse kinematics for a parallel myoelectric elbow

Abstract

Nowadays, myoelectric prostheses for replacement above elbow are serial mechanisms driven by a DC motor and they include only one active articulation for the elbow. Parallel mechanisms are more robust and produce a greater force than serial mechanisms since every actuator participates in the desired movement of the system. Calculating the position of every actuator is more complicated than in serial mechanisms, and as a result, the mathematical models for parallel mechanisms are rather scarce. The inverse kinematics model of a 3-degree of freedom parallel prosthetic elbow mechanism is reported. The mathematical model is required in order to design an above elbow myoelectric prosthesis. The prosthesis under design will have 4 active degrees of freedom and the elbow will employ a parallel mechanical system. The flexion of the elbow, the pronosupination and the humeral rotation are produced by the simultaneous participation of 3 actuators. The grasp is produced by a fourth independent motor. Different derivations of the mathematical model will improve the design of the mechanism of the elbow, with savings in experimentation. Finally, this inverse kinematics model will be employed, using interpolation, in the first control program for the final prosthesis.