Roughness evaluation by wearable tactile sensor utilizing human active sensing

Abstract

Humans can evaluate roughness on various shaped surfaces. Conventional roughness measurement sensors are difficult to apply to curved surface or small product's surface. In this paper, a simple tactile sensor utilizing human ability based on haptic bidirectionality is developed for the roughness evaluation. Humans can move their fingers while perceiving tactile sensations and change exploratory movements like contact force, scanning velocity, direction, etc. according to haptic perception and task objective. Our developed sensor is composed of two microphones and is mounted on a human fingertip. It allows users to touch the object without haptic obstruction. Users can apply the sensor while retaining their normal haptic perception and simultaneously obtaining vibrations and sound based on the mechanical interaction between the finger and the object. First, influence of contact force and scanning velocity on the sensor output is investigated. The experimental results show that the sensor output increases with a rise in the contact force but the influence of the scanning velocity varies between individuals. Then, on the basis of the results, experiment of roughness evaluation is conducted for flat surface and curved surface. A constant normal force and scanning velocity are exerted and the collected sensor output is calibrated by using the sensor output for the middle-roughness sample. The results show that the sensor is capable of evaluating roughness on both flat surface and curved surface in the same rating.

Keywords

• tactile sensor
• bidirectionality
• roughness evaluation
• curved surface
• wearable sensor