Accuracy assessment of kinect body tracker in instant posturography for balance disorders

The accuracy of the body-tracking algorithm of Microsoft Kinect SDK was investigated with the aim to apply the device to the medical care of balance disorders. We focused on the inclination of body posture, assuming that Kinect is used for instant posturography in the test of balance. Subjects were asked to participate in several balance tests and the positions of motion-capture markers on subjects were recorded simultaneously with Kinect body-tracking measurements. After calibrating coordinates and compensating for temporal delay between the two sensor systems using a hybrid marker, the correspondence between the body-part locations of Kinect and those of motion capture was modeled by a linear combination model of neighboring markers with optimal parameters, which were estimated according to the criterion of trajectory minimization. The experiment for six healthy adults showed that our method can track body motion at the accuracy required for standard balance tests.