| Food safety issues related to people's standard of living and good health. With the further deepening of reform and opening-up, driven by economic interests, China's food safety problem is becoming increasingly serious, doped adulterated food processing, additive standard, the use of processed foods such as raw material deterioration illegal activities become all too common, Even some large state-owned food enterprises are no exception. All of these seriously affect the health of our residents. As China's overall national strength, governments at all levels has began to manage and specific the food markets, food safety testing instruments sharp increase in demand. In the context of this demand, Changchun ? Jlu Swan Instruments Co., Ltd. in light of its advantages of front-end principle of chemical analysis, put forward the issue: research on general technology of intelligent portable food safety testing instruments.Detection of food safety mainly through quantitative detection of pathogenic micro-organisms in food, pesticide residues, veterinary drug residues, heavy metals, pollutants, food additives, and other material harm to human health. The temperature in a particular environment or a specific course of temperature change, the material itself is showing some unique optical properties, in some cases, add the appropriate reagent or the material with a specific chemical reaction occurred after a special optical properties, by measuring its optical properties, such as absorbance, astigmatism, reflective degrees and with analytical chemistry methods, we can detective these substances quantitatively. In such cases, the paper developed a set including "temperature control system", "Photometric Detection System", "human-computer interaction system", "the main control system" and "host computer data analysis system," five parts of the portable food general safety testing instrument technology and initial products has formed.Temperature control part designs a set of power cryogenic control systems that covers high, medium and small sized temperature, DS18B20 and PT1000 platinum resistance are used as temperature sensor according to the different needs. Control algorithm uses fuzzy control algorithm as the core. Fuzzy control algorithm is a digital control technology which is based on fuzzy set theory, fuzzy linguistic variables and fuzzy logic, and its basic control idea is to simulate human control thought by the use of computers, the direct control of the use of language-based rules, does not require the establishment of the precise mathematical model of the controlled object. Fuzzy control algorithm is based on the inspired language of knowledge and decision-making rules designed to have a certain level of intelligent control system and strong adaptability, and robust, interference and control parameters on the effect of weak, suitable for non-linear, time-varying and time delay control systems. This section describes in detail the application and realization of fuzzy control from the design of fuzzy controller, fuzzy processing, fuzzy reasoning and fuzzy. The middle and high temperature part of the control system take the platinum resistance as temperature sensor with the fluctuations of less than 0.3℃under steady-state temperature, low temperature uses DS18B20 as a temperature sensor, it can be used for both heating and cooling, with the fluctuations of 0.0625℃under steady-state temperature. In addition to fuzzy control, the software section also describes program flow of I/O port simulation single-bus, I / O port simulation bus I 2C .Photometric detection part take the single-color LED as light source, integrated optical frequency converter TSL230 sensor as the light intensity. The integrated light sensor TSL230 with the photosensitive wavelength of 300nm～700nm, which is produced by the United States TI intelligent can be used directly to convert the visible light frequency, and the output is the square wave frequency signal, the sensitivity and output frequency can be programmable controlled. This part focus on the light source driver, the method of intelligent software elimination of light intensity mechanical, physical differences and its application in multi-task real-time systems, as well as frequency measurement accuracy of multi-task real-time system.Selection of human-computer interaction systems chooses touch screen and four-button small keyboard as input device, micro-pinhole printer, micro-thermal printer, 240 * 128 points monochrome LCD and the buzzer as output device, so its divided into "touch screen", "printer", " display "," Instrument menu " parts. The touch-screen takes the 4-wire resistive touch screen AMT9532, and the article focuses on the resistive touch screen of the circuit theory, and to coordinate collection Buffeting processing, parameter calibration, as well as the mapping screen. Micro-printer chooses the A-type micro-pinhole printer produced by Shenyang Rongda Electronics Co., Ltd. production and micro-thermal printers of Beijing Weihuang Technology Co., Ltd. production. The two micro-pin printers use 25-pin parallel port, 9-pin serial port two forms, which is like home inkjet and laser printers in external interfaces.On the part of a dot matrix printer, as well as graphic dot matrix LCD graphical arrangement, focusing on the two dot-matrix graphic mapping of the rotation and interpolation processing and micro-screen printer in real-time multi-task System. LCD using 240 * 128 dot matrix LCD monochrome points, the part about the anti-jamming displays focus on the hardware driver circuit. The equipment menu section describes basic menu structure of tree, star, mesh equipment, the use of tree-like, star-shaped structure of the way of mixed human-computer interaction will be part of the system shows together 23 interface. At the same time, also focus on the part of the menu and the menu of rights management in a multi-secret mission to deal with the procedure under real-time system processes.The main control system uses a motherboard core board + system approach to design in general LPC21xx series ARM7 microprocessor core board and a total of 21 general-purpose interface motherboard with a 3.3V level UART interface, a RS232 interface, a 25-pin micro-parallel printer interface , a 26-pin double row of micro-parallel printer interface, a 20-pin 240 * 128 dot matrix LCD display interface, a two-pin 5V backlight display interface, a small 5-pin four key keyboard interface, a 4-pin Resistive touch-screen interface, a two-pin 5V power input interface, the two 3-pin PWM output interface, three 3-pin single-bus digital interface, a platinum resistance temperature sensor interface, a 10-pin interface photometer, a USB2.0 host interface, a USB2.0 interface from the plane, a 0-0.3V input A / D acquisition interface and a 5-pin SPI interface. Software focused on the bare metal part of a state of real-time task scheduling and management, the task decomposition and discrete processing.PC data analysis system compiles the data transmission coding and decoding and data analysis processing software, which is linked through curves documents. The data transmission coding and decoding software introduces the self-defined transmission control protocol, as well as the storage file format. Data analysis processing software describes the curve detection of a text file, extraction of curves and data format conversion, general-purpose technology of curve inflection point, bump package, the search for extreme points and the positioning of the cutting and zoom processing technology, with the show of data analysis results charts of the "oil adulteration detectors", which is the first whole apparatus made by the general technology. |
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