摘 要

随着交通便利使得货物的运输变的越来越便捷，尤其是针对于果蔬这类易腐败商品的运输。现代科技的发展赋予了交通运输行业更多的智能化特点，结合果蔬在运输过程中的环境监测，可避免果蔬在长时间的运输过程中发生腐坏现象，影响到果蔬的品质。

本文结合物联网技术，提出一种基于无线传感器网络的果蔬冷链运输温湿度监控系统设计，可用来对车辆运输过程中的内外温度进行检测，并将其用来作为调节车厢内温度的重要手段。设计分为主从两部分，其中主机由STM32 单片机、GSM模块、Zigbee协调器、OLED显示屏、继电器等电子元器件组成，可接收终端节点发送过来的传感器数据，并在显示屏幕上进行显示和控制继电器执行制冷操作，并由GSM模块将采集到的数据发送到服务器端，用户可通过上位机或者手机APP查询数据和进行控制；主设备则是由STC89C52单片机作为控制器，并结合DS18B20 温度传感器、DHT11温湿度传感器和Zigbee终端节点，时间对环境数据进行采集和传输。

本文研究的是基于无线传感器网络的冷链运输温控系统设计，本文主要所做的工作下:

（1）查阅相关的文献资料，对冷链运输的国内外现状进行研究，并完成系统整体框架的设计, 结合无线传感器网络和单片机控制技术，运用传感器来实现对车厢内外的温度进行采集，将其应用在现代物流冷链运输监控中，采用DS18B20温度传感器来实现对运输车内的温度进行采集，同时可通过DHT11温湿度传感器对车厢外的温湿度数据进行检测，并由终端节点将传感器采集到的数据通过无线传感器网络发送给协调器，由协调器进行处理后通过GSM模块将数据上传到本地服务器，供用户进行查询和远程控制；

（2）结合系统整体设计，分别对系统的软硬件部分进行设计，其中硬件部分包括电路图的设计以及硬件电路的焊接等，采用Altium Designer工具来完成电路原理图的绘制。软件部分则采用Keil工具来进行程序代码的开发与调试；

（3）结合系统的硬件电路来完成系统功能的调试与分析，确保系统整体设计符合预期目标^[37]。

系统存在的不足：本设计可以实现对运输车辆在运输过程中的工作状态以及车辆位置进行监控，从而实现对现代物流运输的管理，但是它的交互设计相对较差。物联网技术不仅体现在环境的采集，还体现在运用上。本文虽然可而已采集到车辆的经纬度信息，但是无法对具体位置进行显示和进行道路规划等，这也是现代物流探索的一个方向，这方面仍需加强改进。

关键词：冷链运输温湿度监控；无线传感器网络；GPS定位；GPRS通信

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Temperature and Humidity Monitoring System for Cold Chain Transportation Based on Wireless Sensor Network

ABSTRACT

With the convenient transportation, the transportation of goods becomes more and more convenient, especially for the transportation of perishable commodities like fruits and vegetables. The development of modern science and technology endow the transportation industry with more intelligent characteristics. Combined with the environmental monitoring of fruits and vegetables in the transportation process, it can avoid the deterioration phenomenon of fruits and vegetables in the long transportation process and affect the quality of fruits and vegetables.

Combined with the Internet of things technology, this paper proposes a design of temperature and humidity monitoring system for fruit and vegetable cold chain transportation based on wireless sensor network, which can be used to detect the internal and external temperature in the process of vehicle transportation and as an important means to adjust the temperature in the carriage. Design divided into two parts, master-slave which host by STM32 microcontroller, GSM module, Zigbee coordinator, OLED display screen, relays and other electronic components, can be sent from the sensor data, receiving terminal node and for display on the display screen and refrigeration operation on control relay, and will send the data collected by the GSM module to the server, the user can through the PC or mobile phone APP data query and control; The main equipment is STC89C52 single chip microcomputer as the controller, and combined with DS18B20 temperature sensor, DHT11 speed sensor and Zigbee terminal node, the time of environmental data acquisition and transmission.

This paper studies the design of cold chain transportation temperature control system based on wireless sensor network. The main work of this paper is as follows:

（1）Consulting relevant literature, studying the status quo of cold chain transportation at home and abroad, and completing the design of the overall framework of the system, combining wireless sensor network and single-chip computer control technology, using sensors to collect the temperature inside and outside the carriage, and applying them to the monitoring of modern logistics cold chain transportation, using DS18B20 temperature sensor to realize the temperature inside the carriage. At the same time, the temperature and humidity data outside the carriage can be detected by DHT11 temperature and humidity sensor, and the data collected by the sensor is sent to the coordinator by the terminal node through the wireless sensor network. After processing by the coordinator, the data is uploaded to the local server through the GSM module for users to query and remote control.

（2）Combining with the overall design of the system, the hardware and software parts of the system are designed respectively. The hardware part includes the design of circuit diagram and the welding of hardware circuit. Altium Designer tool is used to complete the drawing of circuit schematic diagram. In the software part, Keil tool is used to develop and debug the program code.

（3）Combining the hardware circuit of the system to complete the debugging and analysis of the system function, to ensure that the overall design of the system meets the expected goal The shortcomings of the system: This design can monitor the working status and position of the transport vehicle in the process of transportation, so as to realize the management of modern logistics transportation, but its interaction design is relatively poor. Internet of Things technology is not only reflected in the collection of environment, but also in the application. Although the longitude and latitude information of vehicles has been collected in this paper, it is impossible to display the specific location and make road planning, which is also a direction of modern logistics exploration. This Fangmian still needs to be improved.

Key words: Temperature and humidity monitoring of cold chain transport; Wireless sensor network; Wi-fi communication