The Accuracy of Screw Axis Analysis Using Position Data from Anatomical Motion Studies

摘要

Research involving the kinematics of human joint mobility often involves screw axis analysis. As a prelude to such research a screw axis analysis program was developed and implemented for use in the Systems Anthropometry Laboratory. This report presents a detailed discussion of the algorithm used to find Displacement Matrices (DM) and screw axis parameters. Error propagation due to uncertainty in DM is analytically developed and then demonstrated. The rotation angle is found to be the most critical screw axis parameter, and the components of a unit vector in the direction of the screw axis are the most sensitive to error. Using the condition number of a matrix, a method is developed and presented for evaluating the error propagation due to the matrix operations used to find DM. (Author)