Reduction of Instrumented Linkage Data for Simple Anatomical Joint Models

Abstract

When measuring the total, six degree-of-freedom (dof) motion permitted by an anatomical joint, it is convenient to attach the ends of an instrumented linkage to the two bodies meeting at the joint and to measure six independent linkage variables as the bodies move. While this method gives a complete description of the motion, it does not permit the motion to be described in a quantifiable manner that non-technical personnel understand. It is therefore often desirable to model the joint as as simple joint which permits fewer than six dof’s, e.g., as a spherical or even a revolute joint. If this is done, a decision must be made as how the six-dof data will be used to define the motion data associated with these simple models. It is the purpose of this paper to present an approach for doing this based in part on optimization theory.