Comparison and improvement of CyberGlove III calibration methods

We investigate the accuracy of different calibration methods for the CyberGlove III for objective hand function assessments. The accuracy is evaluated by means of root-mean-squared errors (RMSE) between ground truth and angles estimated by the glove. Additionally, we propose two improvements. The first increases standardization capabilities for the measurement of pure thumb carpometacarpal joint flexion. The second increases the accuracy by extending an existing calibration method to all thumb and distal interphalangeal joints. The best calibration method is identified and compared to an across-subject calibration by means of RMSEs, highlighting the trade-off between the number of necessary measurements and the accuracy. Our proposed improvements both reduce the measurement effort, while only the second improvement reduces the RMSEs substantially. The best calibration method yields RMSEs below 10° for most joints, while the across-subject calibration has RMSEs that are approximately 5° to 10° higher. We conclude that the CyberGlove III is a suitable tool for objective monitoring of hand movement and function, and the across-subject calibration has the potential to track the range of motion or frequency of joint movements. With this work, we provide an overview for researchers to choose calibration methods suitable for their application depending on necessary accuracy and possible extent of calibration measurements. This work further highlights potential obstacles, when such a glove is used with patients.