RotoWrist: Continuous Infrared Wrist Angle Tracking using a Wristband

We introduce RotoWrist, an infrared (IR) light based solution for continuously and reliably tracking 2-degree-of-freedom (DoF) relative angle of the wrist with respect to the forearm using a wristband. The tracking system consists of eight time-of-flight (ToF) IR light modules distributed around a wristband. We developed a computationally simple tracking approach to reconstruct the orientation of the wrist without any runtime training, ensuring user independence. An evaluation study demonstrated that RotoWrist achieves a cross-user median tracking error of 5.9° in flexion/extension and 6.8° in radial and ulnar deviation with no calibration required as measured with optical ground truth. We further demonstrate the performance of RotoWrist for a pointing task and compare it against ground truth tracking.