CALCULATING POSITIONS OF THE FINGER JOINTS CENTERS OF ROTATIONS IN FLEXION-EXTENSION MOVEMENT FROM REFLECTIVE MARKERS

The aim of this paper is to describe the algorithm for calculating the positions of finger centres of rotation in flexion-extension movement from reflective surface markers. The method presents the simplified version of the kinematic modelling of human motion, developed by various researchers as X. Zhang, S.W. Lee, P. Braido, [1] and Ouerfelli, Kumar, Harwin, [2]. Proposed method uses the mathematical model which connects the fingers internal centres of rotations with the surface markers, positioned on the skin, above the observed joints. An optimisation routine, which minimise the difference between the estimated values of finger segments lengths and these lengths expressed by the distance between surface markers, is employed. As results, the positions of internal centres of rotations were obtained. The efficacy of the proposed algorithm is tested by using data measured during the flexion-extension movement of index finger. Results were compared with the data obtained and published by X. Zhang, S.W. Lee, P. Braido, [1]