Implementation of an Extended Kalman Filter for optical motion capture with real – time 3 D visualization

The technology for tracking reflective markers in 3D using IR cameras is currently mature and widely available, which makes optical motion capture the most popular approach for analyzing human motion. The method consists of recording the trajectories of several markers attached to anatomical landmarks, and then using these trajectories to reconstruct the motion of a rigid multibody model that represents the underlying skeletal system. This method has multiple sources of error, due to the inaccuracy inherent to biomechanical systems. Unless CT scan or similar data is available, the exact geometry of the skeletal system is unknown. In addition, the ideal joints commonly used in multibody models do not always represent the actual kinematics with accuracy. Furthermore, the marker trajectories are perturbed by noise from the capture system and, more importantly, they undergo significant displacements relative to the skeleton, known as skin motion artifact.