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In logistics supply chain management, RFID tags can be used for material and product tracking throughout the supply chain process. From supplier supply to production, warehousing, distribution, transportation and sales. Production enterprises, in manufacturing units (such as workshops), require orderly and correct production processes; in storage units, raw materials and products (semi-finished and finished products) are required to be accurately classified and placed. In order to ensure product quality, raw materials and semi-finished products must be processed, packaged, marked, placed and stored in the warehouse, and through the manufacturing process of the workshop, the finished product is produced and then returned to the warehouse. In each process, the label is required to be attached to the production and storage unit of the material to avoid loss of product information and errors. Therefore, it is necessary to use modern positioning and communication technology to establish a full-time, full-airspace, and all-weather logistics tracking and communication information system that meets the requirements and development of modern logistics supply chains.
Logistics Tracking Information System LTIS
LTIS is used to track and record the circulation information of materials (raw materials and products), warehousing and transportation vehicles in logistics units such as product planning, workshop production, warehouse management, loading and unloading, and remote transportation.
1 LTlS architecture
RFID can identify and track specific materials, and can realize the association and synchronization of logistics and information flow. To track the label and the object pasted with the label, it is necessary to record the circulation history of the material. LTIS uses the remaining memory of the tag to store and update tracking information that cannot be included in the 64-, 96-, or 256-bit electronic product code (EPC) in real time. To this end, three important forms are designed, which are labels, logistics tracking, and historical operation forms. These tables record the history and current situation of material circulation. LTIS hardware consists of tags, fixed readers, portable readers, workstations distributed in different places, a series of fixed application servers, RFID middleware servers, web servers and database servers, Wi-FiLAN, and GPS terminals. Figure 1 shows the architecture of the LTIS solution.
In order to balance the workload, make network update and maintenance more convenient, and conform to the existing logistics enterprise’s intranet and database standards, LTIS software uses a distributed 3-level client/server architecture system. In addition, the browser/server structure is used as an additional solution.
LTIS software includes 6 functional units: raw material and semi-finished products processing subsystem; warehouse monitoring subsystem; material tracking subsystem; system management subsystem; material unit and logistics unit Wi-Fi positioning subsystem; logistics transportation unit GPS positioning and navigation system.
2 LTIS of Wi-Fi/GPS/RFID solution
Because the logistics operation space is very broad, or like a logistics transportation unit, far away from the base and the working environment is closed, this has created obstacles to the application of most traditional RFID solutions. It is too expensive to develop an RFID reader infrastructure that can provide the location of goods and equipment in real time, and requires the installation of antennas in the work area. For this reason, this article designs the LTIS of the Wi-Fi/GPS/RFID solution. This system is similar to AeroScoutu’s newly launched Unified AssetVisibility (UAV) solution. The Wi-Fi/GPS/RFID solution can meet the positioning requirements of material units and logistics units in a wide area, even in remote areas where Wi-Fi access points are sparsely distributed.
LTIS’s Wi-Fi/GPS/RFID solution provides a solution by combining GPS and Wi-Fi active RFID tags. The software allows users to locate the labeled items according to the strength of multiple standard 802.11Wi-Fi access points receiving tag signals, and the access points also serve as RFID readers. When the tag is too far away, its signal cannot be received by at least three Wi-Fi access points, the GPS receiver embedded in the tag can determine its latitude and longitude, and then send the data through the Wi-Fi signal.
When working in GPS or Wi-Fi mode, the tag can be located within 510in. However, GPS does not work in all environments. Some logistics units are closed and cannot receive satellite launches. Each logistics unit needs a certain number of Wi-Fi access points, and the network can receive signals from tags at any location in the logistics unit.
Label the positioning target. The tag needs to contain Wi-Fi and RFID chips, antennas, GPS chips, motion sensors and batteries.
When the job task is received, the employee judges what tools are needed to complete the task, and enters the name of the device on the LTIS software independent system of the Wi-Fi/GPS/RFID solution. The software then displays the floor plan of the logistics unit, with icons on the map indicating the location of the items. The system can also search for all devices according to the selected category.
The tag sends the ID code and GPS data at a set interval. Since the tag is embedded with a motion sensor, when the device is stationary, the signal transmission frequency will be lower than that of the mobile.
The final plan is to integrate the Wi-Fi/GPS/RFID system into the existing inventory management and extend it to all logistics units for use in larger areas of logistics sites, such as airports and ports.
3 Design and implementation of LTIS
In LTIS, applications directly communicate with hardware devices. The Wi-Fi/GPS/RFID system includes equipment, applications and RFID middleware. In order to ensure the stability of the system, another application is designed to connect the RFID reader and client application as a backup solution if the RFID middleware server fails. But need to call the local dynamic link library.
(1) The communication between the application and the RFID reader. Due to different operating frequencies, there are four types of RFID devices. In logistics companies with a variety of materials and a complex working environment, considering the processing speed and the allowable range of the frequency spectrum, flexible selection should be made according to the requirements of logistics operations. In the logistics unit, choose a fixed RFID reader module, such as the $6500 long-distance reader module produced by Texas Instruments (TI), which can meet all RF and digital functional requirements and can be compatible with Tag-itHF supplied by various suppliers , Tag-itTMHF-I (International Organization for Standardization 15693 standard) communicates with all other ISO15693 standards.
This article uses two methods to communicate with the reader. One is that the application software with the $6500 reader on the client computer communicates by connecting to the local dynamic link library. TI provides program libraries feisc.dll and fecom.du. As shown in Figure 2.
The other is to install an RFID middleware for connecting the reader and the client application. The above-mentioned dynamic link library files (fecom.dll and feisc.du) are written with Microsoft basic classes. Use Java, adopt the method of calling the local link library, use Visual C++ and design the middleware according to the Java Native Interface (JNI) standard. RFID middleware is based on three parts: reading interface components, event management components, and application management components. The structure is shown in Figure 3.
The application of RFID reader needs to pass the RFID middleware server, which can support distributed network applications. It makes heterogeneous RFID readers from different vendors compatible and makes applications independent of specific hardware and language environments. The portable RFID reader can read and consult the information stored on the tag. The portable RFID device is composed of an RFID reader module and an intelligent terminal. They are connected via RS232 or other interfaces.
(2) Implementation of Wi-Fi/GPS/RFID
① RFID smart equipment includes 3 parts: RFID data information collection unit; data carrying unit; information transfer unit.
Through these 3 units, the RFID smart device is integrated on the smart terminal. The platforms that can be selected include WindowsMobile, WindowsPocketPC (windowsCE), AndroidOS, LinuxOS. The smart device will complete the data collection and real-time update according to the data instructions provided by the system management center. The data unit structure is shown in Figure 5.
The bottom layer is the operating system and hardware configuration, you can choose WindowsMobile, CE, Linux, Android and symbian system. The hardware suppliers that can be selected include: TI, Qualcomm, Freescale, Samsung, MTK, Broad-com, MarvelandIntel.
At present, these smart terminal devices are easy to find in the market. You only need to develop the standard C and C++ source code or RFID use kits and interfaces in the system to these hardware devices.
The data bearing unit includes the mainstream communication units currently used in the domestic market, including GSM, WCDMA, CDMA, TD technology, and Wifi technology. These technologies can provide a real-time data exchange environment for smart terminal devices, and can call the corresponding data communication unit when needed.
The RFID unit is responsible for identifying the relevant information of the hardware device. The smart terminal is responsible for maintaining the collection and processing of RFID information at the location. Due to the intervention of the operating system, the data terminal is responsible for the coordination and reporting of all tasks.
②Example. Each piece of goods has an RFID tag; the smart device is responsible for collecting information about the current area of the goods, and providing statistics and reporting functions. General logistics personnel can understand the situation of the goods (under the logistics conditions, the smart device needs to be placed on the logistics vehicle); on the vehicle There are 200 pieces of goods, and the smart terminal device can read these data and update the data to the server in the headquarters in real time according to the instructions of the system.
4 Basic functions that smart devices can complete
(1) Inquiry service. On the network platform provided by the company, the functions that can be inquired for ordinary customers, including logistics status (traditional information such as delivery, logistics starting location, etc.).
(2) Tracking function. Among them, for fixed partner customers or large customers, adding GPS location information reporting can allow customers to know the location of the goods at any time. (When the system issues an instruction, the smart device will transmit RFID information, Wifi and GPS positioning information to the company platform.)
(3) The function of regular reporting. According to the system’s pre-settings, the equipment can activate SMS and email reminders in real time when the goods arrive at the designated GPS information point or a fixed wifi area. The information of the reservation is delivered to the customer who made the reservation in real time.
(4) Expand functions. The equipment can be integrated with the current logistics company’s system platform, and the user terminal interface can be extended to smart devices (similar to notebook functions). The operator can manage and update the company’s logistics data through permissions.
Expanded functions include: for professional customers, to provide high-level development of continued smart terminals, including data collection, data update, road condition services, video services, etc.
Logistics Tracking and Communication Information System LTCIS
Wi-Fi, GPRS, INMARSAT, and Internet are all technically mature communication information systems with independent communication standards and network structures. In the logistics transportation unit and other logistics units in the supply chain, especially in the information transmission and data exchange with the central control information center, it plays an independent and complementary role. Through mutual coupling and networking, a reliable and practical logistics communication information system (LCIS) is established, which becomes the antenna and information highway connecting the material tracking information system, the logistics tracking positioning navigation system and the central control system. LTIS (Wi-Fi/RFID/GPS), LCIS (Wi-Fi/GPRS/INMARSAT), MIS (ManagementIn,formationSystem) systems are coupled through communication standards to realize networking and establish LT-CIS, which is technically There are no obstacles. The architecture of LTCIS is shown in Figure 6.
in conclusion
This paper proposes a solution for a logistics tracking information system integrating RFID, GPS and Wi-Fi. And on this basis, combined with the latest communication technology, conceived an all-weather, all-time-space LTCIS network. It is a good enlightenment and attempt to connect, smooth and globalize the supply chain of logistics enterprises.
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