Study of Infrared Techniques Applied in Range-finding and Fires-detecting

• Main Authors: Yuan-Kai Wu, 吳元凱
• Other Authors: Chin-Fu Tsai
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/38320780988094120408

碩士 === 國立勤益科技大學 === 電子工程系 === 99 === Infrared techniques are usually applied in our life, such as CCD camera, the automatic valve, Infrared Data Association (IrDA) and so on. This study is to perform an object locating and the research of new fire detection by means of infrared techniques. In the location of an object, our objective focuses on the short distance measuring. To estimate the location of target is based on the phenomenon which infrared signal reduces with distance square increasing. The low-cost reflective photo-coupler is used in the experiment to take range-finding. By circuit techniques, we successfully eliminate the interference of the environment; and let the IR sensor accurately detect the position of a target. Additionally, we investigate the differences in the detectable range and resolution between using a discrete type and using a modular type. The experimental design was of using a movable work platform driven by a stepping motor, and using a data-acquisition (DAQ) interface to obtain the measured data via the Laboratory Virtual Instrument Engineering Workbench (LabVIEW) software on a PC. The movable mechanism which sets up the tested sensor can get a resolution of 0.1 mm and 1 mm in displacement. Experimental results show that the modular type is suitable for measuring in the near distance (2~15 mm) but the discrete type is used in the further distance (25~250 mm). Traditional fire detector is to check whether there is a fire or not from temperature or smoke which must be sufficient so as to start alarm. Using the techniques of radiometry, this study proposed a remote monitoring system which can start alarm while the fire breaks out. We take a pyroelectric infrared (PIR) sensor working in a specific waveband (4.3μm) to detect fires and heat CO2 released from combustion. Besides, we use a non-contact K-type thermocouple to monitor the temperature in a simulated smolder environment, so as to prove the examination data of the PIR sensor. The experimental processes show that this system can accurately detect flames and infrared radiated from CO2. A micro-controller MSP430 is used to digitize the received signal. Finally, the measurement results were presented by graphical program software LabVIEW at personal computer via the XBee wireless communication. In the future, this new fire detector will be developed a portable device.