A systematic method of obtaining three-dimensional kinematic parameters of the various segments of the musculo-skeletal system of human using cinematographic information is studied to improve its accuracy.
Modified direct linear transformation algorithms with three dimensional calibration frame is used for camera calibration. The cutoff frequency of the low pass filter is determined using a statistical error analysis for noise reduction and differentiation of the trajectories of anatomic points. To describe the relative motion between bodies, the lower limb modeled as three rigid links(thigh, shank, foot) connected by three hinged joints, ie the hip, knee and ankle joints.
Through this study, it is found that the suggested algorithm provides reconstruction of positions with an average accuracy of about 0.2%. It is suggested that the low pass filter cutoff frequency should be different for every joint in the range of 4Hz and 10Hz.