Artificial tactile sensors with various types of sensing mechanism have been developed in order to mimic the human’s tactile sensations in nowadays. Among many input parameters which provide useful information about skin state, especially, sensations of temperature and pressure are the most important tactile factors, because these can be used to generate advanced tactile sensation such as pain, vibration, hardness. Therefore, these two senses are the important mimic points of artificial skin technology, for realization of an artificial tactile system. we should consider mechanisms to detect these two parameters, temperature and pressure, and a systematic integration. To measure these external stimuli, data acquisition with connecting wire between the sensor and the signal processor are required. However, when integrating numerous amount of various unit sensors, the same number of wires as elements are required. As a result, numerous wire connections cause the limitation of designing sensors with complexity of the sensor structure. In this paper, the design of temperature sensor was simplified utilizing a single resistor placed on top layer of the hybrid sensor system and the method was studied to enhance sensitivity of thermal detection the same as one of the multi-thermal sensor array design. To measure exact the temperature value of object, which is smaller than the size of sensor, the signal processes was developed by capturing maximum slope of the resistance variation on a single resistive sensor and utilizing the area information which is acquired from micro sized pressure sensor arrays positioned under the temperature sensor. Slope provides information related to total thermal energy and a more precise temperature value was calculated utilizing an area information on pressure sensor arrays. As a result, the hybrid tactile sensor detected successfully the temperature levels from various dimensional contact stimuli with under 300msec response time as well as different pressure levels and the shape of objects.
Table Of Contents
Abstract i List of contents ii List of figures iv
Ⅰ. INTRODUCTION 1.1 Overview 1 1.2 Motivation 2
Ⅱ. BACKGROUDNS 2.1 Human Tactile Sensing system 5 2.1.1 Tactile Receptors 5 2.2 Previous Works 7 2.2.1 Pressure Sensor 7 184.108.40.206 Piezoelectric Sensor 7 220.127.116.11 Capacitive Sensor 8 18.104.22.168 Triboelectric Sensor 8 22.214.171.124 Piezoresistive Sensor 9 2.2.2 Temperature Sensor 9 126.96.36.199 Pyroelectric Sensor 9 188.8.131.52 Thermoelectric Sensor 10 184.108.40.206 Resistive Temperature Sensor 10 2.2.3 Multi Sensor 11 2.3 Principle of Piezoelectricity 11 2.4 Principles of Resistive Temperature Sensor 13
Ⅳ. RESULTS AND DISCUSSION 4.1 Temperature sensor signal 22 4.1.1 Fast detection 26 4.1.2 Area classification 31 4.2 Pressure sensor signal 33 4.3 Hybrid sensor signal 37 4.3.1 Equation analysis 38 4.3.2 Signal classification 40