A 3D-Printed Device for Unconstrained Grip Force Measurements: Design and Application in a Human Experiment

A measurement device was developed that can measure user-applied grip force all around a cylindrical handle without constraining the grasp posture. Through the use of flexures, the device mechanically sums the radial grip forces, up to 200 N, applied to any locations along any of its load plates. It exhibited less than 1.5% of full-scale error after calibration and less than 1.5 N variation when load was applied to different plates. The device used off-the-shelf and 3D-printed components, making it easy and low-cost to build and use. The accuracy and versatility of the device affords numerous applications in research on human motor control and human-robot interactions. A human experiment on force tracking was presented to demonstrate the utility of the device.