Robust estimation of dominant axis of rotation.
A simple method is developed for robustly estimating a fixed dominant axis of rotation (AoR) of anatomical joints from surface marker data. Previous approaches which assume a model of circular marker trajectories use plane fitting to estimate the direction of the AoR. However, when there is limited joint range of motion and rotation due to a second degree of freedom, minimizing only the planar error can give poor estimates of the AoR direction. Optimizing a cost function which includes the error component within a plane, instead of only the component orthogonal to a plane, leads to improved estimates of the AoR direction for joints which exhibit additional rotational motion from a second degree of freedom. Results from synthetic data validation show the ranges of motion where the new method has lower estimation error compared to plane-fitting techniques. Estimates of the flexion-extension AoR from empirical motion capture data of the knee and index finger joints were also more anatomically plausible.
Chang
Lillian Y
LY
School of Computer Science, Carnegie Mellon University, 5000, Forbes Avenue Pittsburgh, PA 15213, USA. lillianc@ri.cmu.edu
Pollard
Nancy S
NS
D005384:Finger Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008954:Models, Biological; D009068:Movement / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D012984:Software