Improving skin artifacts compensation for knee flexion/extension and knee internal/external rotation

When the motion of the human body is studied by means of marker-based motion capture systems, one of the main source of error in this analysis is caused by the markers movements with respect to the underlying bones due to skin motion and deformation. In the kinematics estimation of the lower limbs this error is particularly notable for the rotations in the frontal and axial planes. Many algorithms exist trying to compensate this problem, most of them giving satisfactory results in the estimation of the knee flexion/extension, but correcting the effects of the skin deformation in other rotations is still an open issue. We have implemented a new algorithm to compensate this problem. This method was evaluated on a motion of the human lower limbs and compared with another existing global approach. The results of this experiment showed that the proposed algorithm gives much better results in the analysis of human motion, particularly for the internal/external rotation of the knee.