Photogrammetry based motion tracking systems are widely used in entertainment, medicine, sports, and other industries for low accuracy positioning applications. Camera-based systems track cooperative markers on objects to obtain their real-time positions and poses. There are few detailed studies in the literature on metrological analysis in three-dimensional (3D) space for such systems because they were primarily used in the entertainment industry and their off-the- shelf accuracy was not a key concern. However, applications for these systems have become more widespread due to their low cost and high repeatability, and there is promise for applicability in metrology grade applications after suitable modifications. In this context, we investigate the error sources of a motion tracking system by error mapping in 3D space using a coordinate measuring machine (CMM) with two orders of magnitude higher accuracy. With the understanding gained from this study, we propose three different methods to improve the accuracy of motion tracking systems: interpolation based on experimentally determined error map, error correction based on scale bar measurements, and weighted averaging using two motion tracking systems. Verification experiments are presented for each method.
Optics and Lasers in Engineering
Motion tracking system, Error mapping, Scale bar, Weighted averaging