Hand-Finger Pose Estimation Using Inertial Sensors, Magnetic Sensors and a Magnet

Hand-finger motion tracking based on inertial and magnetic measurement units (IMMUs) has become a well-accepted method in many applications such as rehabilitation and virtual reality. However, existing systems require an IMMU on each segment of the whole hand and known length of each segment, which is hard to achieve for users. Therefore, we proposed a small sensor configuration with three IMMUs and a magnet to estimate poses of interested fingertips relative to the hand. The relative orientations were estimated by integrating relative angular velocity and fused with relative orientation estimation during time intervals when the whole hand moved or rotated as one object. The relative positions were estimated by using a magnetic dipole model of the magnet and prior estimated relative orientations. The performance has been demonstrated in multiple experiments. For whole hand rotation and functional grasping or writing experiments, the estimated errors of index fingertip position and orientation relative to the hand were 8.0~9.8 mm and 5.7° ~11.2°. For index finger flexion and pinching, the estimated errors of index fingertip position and orientation relative to the hand were 16.2~25.2 mm and 20.6° ~ 21.7°.