Force Characterization Of Meso-Scale Haptic Devices

Recent advances with haptic devices have shown great potential in physically simulating contact with an object. In meso-scale (1 to 10 cm) haptic devices, although the actuation level can be controlled, their small form-factor makes it difficult to measure the actual forces felt by the wearer. Therefore, researchers often report the qualitative evaluation using user studies, which contribute little towards quantifying the effectiveness of their haptic devices. There is a need for systematic mechanical characterization of such meso-scale haptic devices, which will lead to their improved design, control and overall effectiveness. To address this, here we design an experimental protocol for characterizing the mechanical behaviour of a fingertip haptic device (haptigami) by using a robotic test platform and a tendon routing system. We enforce planar displacement on the haptigami, and measure its force vs. displacement behaviour. We fit the measured data using linear regression, which yields a second order model with root mean squared errors under 5.3%. With the capability to effectively quantify the mechanical performance, this is a step towards benchmarking and comparing meso-scale haptic devices.