Research On Near Infrared Reflective Detection Method For Wheat Moisture

In food processing, transportation, storage and circulation process, the moisture content is a very important parameter. Grain moisture directly affect food quality and storage time, therefore, the grain moisture measurement and control is of great importance. Traditional moisture detection with Karl fisher method, capacitance method and conductance method, the measurement methods such as testing time is long, can’t online test or test parameters of a single, etc. Near infrared moisture detection is a kind of water is used for a specific wavelength near infrared absorption properties of the light beam, by measuring the near infrared light beam in the loss of the incident energy before and after the object under test to determine moisture content of the object under test method. This method has a high speed, non-contact, continuous and online measurement, etc.The goal of this thesis is based on the theory of near infrared moisture measurement and the characteristics of portable measuring instruments, the research of the portable near infrared wheat moisture detection technology, for further research and development of portable wheat moisture tester and wheat quality sensor provides technical support online. Based on the research of the near infrared measurement methods at home and abroad, this paper studies the include light source, photoelectric detector, the geometric conditions were determined, and A/D sample, control logic, data processing and correcting, determine the overall system architecture. To test device has the advantages of simple structure, stable work, avoid the use of complex structure, higher spectral system cost, this article choose 0 / 45 ° measuring geometry; Choose LED as near infrared light source, its center frequency is 1450 nm, near 1430 nm characteristic absorption frequency; Near infrared sensor selection response spectra of 800 ~ 3200 nm PbS ir detector. Based on the needs of the control logic and data processing, and also give consideration to reduce the cost of requirements, the test device is the main processing unit selects STC12C5A60S2 microcontroller. This paper studied the common spectral data processing method, the research and development the median filtering, average filtering, moving average filtering and the weighted median filter, the adaptive median filtering and so on data processing algorithms. In the hardware design and debugging process, but also to the stability of the system hardware and software and the anti-interference measures were studied. Experimental results show that for the preparation of wheat cascade water samples, this paper developed by near infrared reflection type wheat moisture measuring device measuring data and the actual water correlation coefficient of 0.86. This paper developed a device has simple structure, easy to carry, fast, low cost, etc, for the further research of the portable and online wheat moisture measuring instruments laid the important technical foundation.