The Design Of High-precision Infrared Temperature Measuring System

The body health is of great importance to a human body and the body temperature is a basic signal which can reflect the health level of human body.When the body is attacked by the diseases,the temperature of body will rise up,such as SARS in 2003,H1N1 in 2009,and 2019-nCoV at the beginning of this year.The methods to measure the temperature can be divided into two categories: contact and non-contact.And the non-contacted method is of great advantage.This kind of method can measure temperature with high speed and don't have the risk of cross infection,compared with the traditional mercury thermometers.Non-contact measurement does not affect the temperature field of object.Especially,it played a crucial role in the fight against2019-nCoV.Aiming to design a non-contact infrared temperature measurement system with error compensation,I read a large number of papers and analyze the basic theory of infrared temperature measurement.The main work and research of the thesis are as follows:First of all,this paper introduces the development and research status of temperature measurement technology all around the world.And then analyze the situation of contact temperature measurement and non-contact temperature measurement,describe the application filed and the direction of development of infrared temperature measurement technology.According to the functional requirements of the infrared temperature measurement system,the technical indicators and technology program are given.Secondly,in term of hardware design,we choose STM32F103RCT6 as the MCU,BM43 THA as the infrared temperature sensor,AD8551 as the amplifier,ADS1255 as the AD converter,and VL53L0 X,DS18B20 and DHT11 are also used for the error compensation.we design the circuit of the sensor,the amplifier circuit,the AD converter circuit,the peripheral circuit of the MCU,the OLED display circuit,the alarm circuit,the USB communication circuit and the WIFI wireless communication circuit.And then,in term of software design,the overall software design of the infrared temperature measurement system and the software of each module are independently designed.The least square method is used to perform polynomial fitting to obtain thecorresponding relationship of the object temperature,the infrared thermopile signal and the thermistor signal.We use C# to complete the upper-computer software in Visual Studio.The system can achieve the function of temperature measurement distance,ambient temperature and ambient humidity error compensation,high temperature alarm,communication with computer and the communication with mobile phone.Finally,the data collected by the infrared temperature measurement system is pre-processed using large deviation filter and Kalman filter to filter out the junk data.And then I do a lot of research on the GA-BP network algorithm and the PCA-GRNN network algorithm.The related experiments are carried out on the three aspects of distance,environmental temperature and environmental humidity.Comparing the results of the two temperature error compensation algorithms,GA-BP neural network has more advantages in error compensation.Finally,the system basically reached the expected technical indicators,effectively reducing the errors caused by the ambient temperature,humidity and distance to the temperature measurement accuracy.