...There are different SW blocks including: unit interconnection, data calibration, data processing and visualization. The data are calibrated by six-position test or two-step algorithm and processed by Extended Kalman Filter or Unscented Kalman Filter. The final data are fitted to the human body model including its limitations and the visualization is performed in OpenGL. System function is illustrated by: http://www.youtube.com/watch?v=Tpy9Vtelppk .