Experimental Validation of a Contactless Finger Displacement Measurement System Using Electrical Near-Field Sensing

This research investigates the potential of contactless finger motion measurement, focusing particularly on ease of use to improve the success of home-based hand rehabilitation exercises. Previously, a mathematical model was developed based on a finite-element method simulation. This article validates this model on multifinger noncontact measuring under laboratory conditions. Twenty-three healthy subjects with normal hand and finger functions participated. An independent near-field distance measurement was developed and compared with the output from an optical sensor. It was observed from the experiment that the prediction model worked well with the measuring system reported here. The average uncertainties of measurement using the prediction model are 0.68 and 0.55 mm, which are 3.5% and 2.7% of the full-scale range for the index finger and middle finger, respectively. The results from the experiment show that the reported system is capable of measuring the small movements of fingers. With the combination of the noncontact measuring feature and the lack of complicated setup, this system is easy-to-use as the basis of a home-based independent rehabilitation system.