Real-time inspection of surface irregularity by finger-mounted tactile sensor

This paper presents the development of a finger-mounted tactile sensor for surface irregularity inspection. 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. In addition, a silicone oil sheet is attached on the bottom of the sensor as a viscous fluid medium for keeping steady contact with the object surface. For mounting the sensor on the finger, the sensor is embedded in a cotton work glove. The user puts his/her finger on the silicone rubber of the sensor and slides the sensor over the object surface. By obtaining difference between the two strain gauges, the sensor responds to the surface irregularity, not to the uniform surface. Theoretical analysis of sensor output signals is presented and real-time signal processing based on the wavelet transform for detection and evaluation of surface irregularity is introduced. Then, experiments using the developed sensor are carried out on some protrusions. The results show the availability of the proposed tactile sensor.