The relationships of gripping comfort to contact pressure and hand posture during gripping

Abstract

A sensory evaluation test on spherical and columnar objects with different cross-sectional shapes was conducted to investigate their gripping comfort. The relationships of the gripping comfort with the measured contact pressure and hand posture during each grasping task were then statistically analysed using regression analysis with a stepwise procedure. The coefficient of determination of the correlation between the contact-pressure distribution and gripping comfort indicated a fairly strong correlation (R2 = 0.55), which is stronger than the correlation between the finger joint angles and gripping comfort (R2 = 0.33). The cross-sectional shapes of the test objects caused variations in the contact-pressure distribution owing to changes of the contacting part and the grasping strategy. Furthermore, the contact pressures on the fingertips, the distal region of the palm close to the index finger, and the proximal region on the palm close to the radius all contributed to the gripping comfort, according to the analysis results. The result allows a better understanding of the performance of contact pressure and hand posture in evaluating gripping comfort as well as the role of local contact pressures in the prediction of gripping comfort. Manufacturers can select the local contact pressures that strongly contribute to the gripping comfort during the assessment of their products.