The study of sensor structure to perceive a surface texture for psychological tactile sensor

Abstract

Tactile sensors mimicking the sense of touch of the human have been studied gradually and various technologies sensing an external stimulus have been suggested as well. The human detects some external physical stimuli and generates psychological feeling such as roughness, softness or pain through the touch. Since people have different criteria for the psychological feelings, there are a lot of issues as to which components are most informative for perceiving the parameters. To give these psychological feelings to artificial system as like android robot or smart phone, sensing a surface texture is one of the most informative perception among various physical parameters. Sensing a surface texture also has many issues since many kinds of factors such as vibration, strain and friction should be considered to detect the surface texture. Robotic fingers applied a contact point analysis, feedback loop and flow chart are used for a surface texture detection in robot field. However, those methods should need complex algorithm and programming to analyze data concerning a surface texture from the robotic fingers. In this paper, a piezoelectric type array sensor structure was demonstrated with sliding mechanism to restore a surface texture precisely as like human. The suggested array sensor design with excellent dynamic response of piezoelectric material gave a higher spatial resolution detection than the resolution of sensor system and detected sliding velocity, essential parameter to restore surface texture from electrical signal, as well. The sensor could calculate various sliding velocities from 10mm/s to 70mm/s accurately by simple electrical signal analysis produced from sensor arrays. A soft material was applied for the sensor to enhance surface detection ability and it allowed that the array sensor could distinguish between a spike type and a doom type shape. Signal processing was optimized and simplified for a surface texture restoration. Restored surface textures had high accuracy compared with real texture structures and color mapping skill was applied for the restored textures images to express the pattern of texture. The capabilities of velocity detecting and texture restoration allow the sensor can be utilized to electromechanical systems as the physical and the psychological tactile sensor. ⓒ 2017 DGIST