【作者】 赵晓峰；

【导师】 朱瑞祥；

【作者基本信息】 西北农林科技大学 ， 农业电气化与自动化， 2010， 硕士

【摘要】 2009年我国《食品安全法》的正式颁布与实施,极大地促进了我国食品的生产、存储、流通和销售等一系列环节向标准化和信息化领域迈进。目前我国农产品冷链物流标准才刚刚起步,冷链建设还处于初级阶段,冷藏车装备技术相对落后,信息化程度低,蔬菜和水果在流通过程中损失率高达25~30%。针对上述问题,本论文采用ARM技术,利用1-wire协议和WinCE操作系统多线程编程方法,设计开发了一种基于ARM的农产品冷藏车环境监控系统,实现了冷藏车环境温湿度数据的在线采集、存储和显示功能,并且采用了变频技术实现农产品冷藏车环境的快速制冷控制,该系统可以满足现代化农产品冷藏车必须具备的一些基本功能。本研究的主要内容及结果如下:(1)选择S3C2410微控制器作为冷藏车环境监控系统的中央控制器,并移植了WinCE操作系统;(2)在信息采集模块设计中,采用DS18B20数字温度传感器和DS2450S模数转换器,与HSM40湿度传感器相结合的设计方案,利用1-wire数据传输协议,对环境温湿度进行了在线检测,一方面大大节约了控制器的I/O口资源,另一方面也简化了布线,降低了相互之间的干扰,保证了信息采集的准确性。实验表明其温湿度的测量精度分别在±0.5℃和±3%RH范围以内;同时,采用WinCE多线程编程技术,增强了环境监测单元的实时性和可靠性;(3)采用无传感器的无刷直流电动机驱动压缩机进行变频调速的方法,对冷藏车制冷系统进行温度调节,相比传统的“定频”调速方式,其制冷速度快、温差波动小,且噪声小、系统安全性高;(4)实现了三相全桥式电机驱动电路对无刷直流电动机进行变频调速。为了及时捕获电机“反电势过零点信号”以检测其转子位置,从而进行正确换相,系统修改了WinCE系统中与中断相关的内核代码以及OAL例程代码,并开发了与中断相关的流式驱动程序;(5)采用自适应模糊PID控制算法对冷藏车环境温度进行调节,并在MATLAB7.0中进行了仿真分析。结果表明其相对常规PID控制抗干扰性强,控制效果更好。更多还原

【Abstract】 The promulgation and implementation of China’s“Food Safety Law”in 2009 greatly contributed to the standardization and information of China’s food production, storage, transportation, marketing and so on. At present, China’s Agricultural cold-chain logistics standard has just started, cold chain is still in the initial stage of construction, and refrigerated truck equipment and technology is relatively backward, with low levels of information technology.The loss rate of vegetables and fruits in circulation is as high as 25~30%.To address these issues, an environment monitoring system based on ARM for refrigerated truck of agricultural products was developed, which applied 1-wire bus protocols and WinCE operating system multi-threaded programming. It realized the function of online collection, storage and display of the environmental temperature and humidity data of refrigerated trucks, and used frequency conversion technology to achieve rapid agricultural environment refrigeration of refrigerated trucks. It met the requirement of a modern agricultural product refrigerated truck with some basic functions. The main content of this study and the results as following:(1) Select S3C2410 micro controller as the central controller of refrigerated trucks’environmental monitoring systems, and migrate the WinCE operating system;(2) Apply DS18B20 digital temperature sensor and DS2450S D/A converter, with a combination of HSM40 humidity sensor in the design of information collection module. Use 1-wire data transfer protocol to take an online test on the environmental temperature and humidity, it not only greatly saved the controller’s I/O port resources, but also simplified the wiring and reduced mutual interference and ensured the accuracy of information collection. Experiment results showed that the temperature and humidity measurement accuracy is respectively within±0.5℃and±3%RH. At the same time, it enhanced the real-time and reliability of environmental monitoring unit by using WinCE multi-threaded programming techniques.(3) Regulate the temperature of the refrigerated truck refrigeration system with the frequency control method by using the sensorless brushless DC motor to drive compressor, compared to the traditional "fixed frequency" speed mode, it is of high cooling speed, small temperature fluctuations, low noise and high system security;(4) Design a three-phase full-bridge motor drive circuit for brushless DC motor’s frequency control, in order to promptly capture the motor "back EMF zero-crossing signal" to detect the rotor position, and thus correct the phase change opportunity, the system changed the kernel code as well as the OAL code of WinCE system, and developed stream drivers associated with the interruption;(5) Apply adaptive fuzzy PID control algorithm to adjust the environmental temperature of refrigerated trucks, and carried out simulation analysis in the MATLAB7.0, the results showed that it is of strong anti-interference and better control compared to the conventional PID control.更多还原