Development of a finger-mounted tactile sensor for surface irregularity detection

This paper presents the development of a finger-mounted tactile sensor for surface irregularity detection. The sensor is composed of a thin rubber sheet and a silicone rubber with the void in the center. On the center of the rubber sheet, two strain gauges are attached point-symmetrically. The user puts his/her finger on the silicone rubber of the sensor and slides the sensor over the objective surface. For mounting the sensor on the finger, the sensor is embedded in a cotton work glove. By obtaining difference between the two strain gauges, the sensor responds to the surface irregularity. It does not respond to the uniform surface. Furthermore, real-time signal processing utilizing the wavelet transform is proposed for detecting surface irregularity from sensor output signals. Experiments are carried out on the plane surface and curved surface with a small protrusion. Moreover, the sensor is improved on the basis of the experimental results. Silicone oil sheet is attached on the bottom of the sensor as a viscous fluid medium for improving unstable contact between the sensor and the objective surface. Using the improved sensor, experiments are carried out. The results show that the proposed sensor is capable of detecting the surface irregularity.