A non-exoskeleton optoelectric wrist goniometer

Highly repetitive wrist motion and extreme wrist posture can result in carpal tunnel syndrome. To study the association between wrist motion and posture and carpal tunnel syndrome, a hand/wrist goniometer is indispensable. This paper describes the development of an optoelectric goniometer. The goniometer utilized a fluid-based absolute angle sensor to transduce wrist posture into electrical signals. A geometric relationship and 6 nonlinear equations were used to calculate relative wrist angles. The result was an easy-to-use and non-exoskeleton hand/wrist goniometer which measures radial-ulnar deviation and flexion-extension of the wrist. Validation results showed that the average error of the absolute angle transducer was 4.5% of the full scale output (180°). Correlation between the output from the sensor and the standard motion was 0.977. Repeatability tests showed that the variation was 6.02% of the input value. The resolution of the sensor was 0.036°.