Wrist Joint Angle Estimation Based on Simultaneous Measurement of Distance and Force on the Forearm

The skin shape of the body, which reflects the static and dynamic activities of body tissues, has been applied to motion estimation. Since the skin shape varies under limb pose and motion speed, it is necessary to combine sensors that capture the deformation with different sensitivities to cover a wide range and variety of deformations. In this study, we investigate the effectiveness of simultaneous measurement of distance and force between the sensor unit and the skin for joint angle estimation. Using the sensor unit in the experiment, we try to estimate the continuous wrist joint angle (an axis of palmar and dorsal flexion) under slow and fast speed conditions and free motion conditions. The experimental results indicate that the combined feature of distance and force achieves the highest accuracy in estimating continuous joint angles under all conditions.