A Tactile Sensor for Measuring the Hardness of Soft Materials

This paper presents a novel tactile sensor with a simple structure for measuring the hardness of soft materials subjected to finite deformations. In principle. this tactile sensor is designed to be as a rigid cylindrical core surrounded by an elastic annular ring. Based on the difference of forces acted on the core and the ring, the indentation displacement can be determined. To evaluate the hardness output, the relation between hardness and elastic moduli is developed. And, the contact processes between the tactile sensor and materials with different hardness are analyzed. It is found that the gradient of the force differences can well reflect the hardness of materials. A prototype of the proposed tactile sensor is being fabricated in our lab.