RF technology and wireless real-time warehouse management system

Jacktang

RF technology and wireless real-time warehouse management system [Copy link]

1. RF technology revolutionizes the logistics industry Imagine that there is a God watching the activities in the warehouse. Whenever a piece of goods is placed in a shipping box by mistake, God will be heard saying: "The goods are placed in the wrong place, and should be placed in another box." God's supervision makes the warehouse well organized, without any misplaced goods, and customers have never received any wrong or missing goods. This God has come to today's logistics industry. It is RF (RADIO FREQUENCY) technology plus a correctly programmed real-time logistics system. What is RF real-time technology? RF technology is a wireless telecommunications technology. The IEEE802.11B standard is currently used more. The high frequency channel of 2.4GHz enables the communication speed between the server and the terminal to reach 12Mbps. Moreover, this channel is not subject to wireless regulation in most countries due to its low interference. The hardware of the RF logistics system is mainly composed of wireless terminals, wireless gateways and servers. The terminal is generally a handheld computer plus a barcode scanner with wireless communication function. The wireless gateway is set up high in the warehouse or on-site, and is connected to the server through RJ45 and LAN cables. The effective communication radius between the gateway and the terminal is 150 meters. If the radius is greater than 150 meters, multiple gateways can be set up to allow the terminal to roam between them, just like a mobile phone network. The terminal and the server exchange signals through the gateway. Since barcodes are still the most effective and low-cost identification method, most logistics systems are based on barcode technology. Hardware equipment includes barcode printers and related consumables. RF real-time software system refers to the program installed on the terminal and server. The system is like an omniscient God, and RF technology ensures that God is everywhere. The system knows all the rules and all the correct operations, and always guides every operation in the system and reports accurate results. The difference between modern logistics and traditional storage and transportation-the soul of logistics industry technology is the WMS system, which has the following characteristics: High level of customer service: all customer needs can be met. For example, accurate information, fast delivery, no loss or wrong delivery, real-time query of the in-transit status of a certain order of goods, change the destination on the way, and provide door-to-door service. At the same time, logistics companies can also meet customers' higher requirements, participate in customers' supply chain construction, and become part of their production and market strategies. Large scale: Logistics companies can deliver goods to a wide range of areas, even to any corner of the world. For example, UPS has more than 100 transport aircrafts to ensure its large-scale cargo transportation range. Fast: Fast service is one of the important characteristics of modern logistics. For example, UPS guarantees that the goods delivered by customers the day before can arrive at any point in North America before 10 o'clock the next morning. When the West Coast of the United States gets off work, it is already late at night on the East Coast. It takes nearly 6 hours to fly between the two coasts. However, UPS can complete the sorting, transportation and delivery of tens of millions of pieces of goods every day in just a few hours, which is admirable. High added value: The express business of the logistics industry is the business with the highest added value. When all logistics storage and transportation capabilities are equal, it is mainly information and services that create value far higher than general storage and transportation, and the storage cost of express transportation is low because the goods stay in the warehouse for a short time. This also explains why the investment in information systems is large but the return on investment is higher, which is also a manifestation of a virtuous cycle of investment. Modern management: In modern logistics, whether it is inventory, shipping site or office location, everything is in order, and the process is fast and smooth. However, traditional warehousing is chaotic and the staff is idle. These gaps are far from just the investment of equipment funds, but mainly the gap in management level. When an enterprise has a scale of 10,000 people, how much wisdom is needed for such a management level! Because of different specific environments, each logistics company needs to customize its own WMS (Warehouse Management System). Many companies think that simply combining the IT team with the current warehouse management personnel to develop a system is WMS. In fact, such a system can improve some accuracy and efficiency, but the logistics level remains at the level of understanding of the original management personnel. RF communication makes it possible for WMS to process real-time data, and the traditional process can be greatly simplified. For example, there were many kinds of original warehouse transfer code sheets, which can now be simplified to one or two operations. The new system can optimize the process, so that most of the traditional processes are omitted and changed. The optimized system means a change in management concept, so who will change the concept of these managers? This external force can be a modern logistics consulting company. Consulting companies help companies determine the best process, then equip hardware and logistics systems, train managers and employees, and select the best solution under various feasibility and complex environments.

Features of WMS based on RF technology: Accuracy close to 100%: Each operation must be verified. For example, the error rate of people is about 1/200. There are about 5-7 operations from warehousing to shipping and inventory. If each step has automatic error correction verification, the total error probability is: (1/200)7≈0. Real-time: The goods that have just entered the warehouse appear on the sales list immediately. What is the total value of each warehouse at this moment? Which goods are moving in the warehouse? Is a customer's goods being loaded? Know these dynamic data systems well. Simple operation: A good system does not require complicated operating procedures and long-term training to master. Workers only need a few simple instructions to complete the task. The system should be like a powerful advanced professional camera, but with the operating interface of a point-and-shoot camera. Programming engineers need long-term experience: the system needs to be used repeatedly in the industry to meet the needs of front-line operators and managers. The system will give feedback on any wrong operation, tell the user what went wrong, and then perform the correct operation again. In any case, the system cannot crash, which requires programmers who have seen all kinds of scenes to use experience to solve problems. A system cannot be considered a mature system if it has not been tested in actual operation for 5 years. Reliability: What if an accident occurs during system operation? Is the data lost? Just like the huge amount of money in inter-bank transactions, the complete database of WMS needs to protect the data of each operation and have the function of loss recovery. Network user environment: Everyone has experienced the scene of operators waiting for the computer to reply to data when buying air tickets or making bank deposits. The WMS system requires simultaneous cross-location picking and placing of goods. If the program efficiency is not high, the system will fail. A good program is simple and has less burden, can withstand multiple users using network resources, and has low maintenance costs. Greatly improve enterprise efficiency and return on investment: The RF system will increase the utilization rate of warehouse area by more than 50%, because the goods do not need to be stacked according to pre-divided areas. The demand for personnel and equipment is also greatly reduced, because accurate information avoids ineffective labor. The realization of zero inventory for customers makes the enterprise's capital flow control reasonable. The improvement of customer service level brings huge potential benefits and direct benefits. A good WMS system can often recover the investment of the enterprise in the first year of implementation. Warehousing enterprises can truly transform into modern logistics enterprises by relying on RF technology.

2. Basic functions of wireless real-time warehouse management system: The wireless real-time warehouse management system is an automated real-time warehouse management system based on barcode technology, fully applying wireless network communication technology and wireless handheld computer terminals, combined with C/S and B/S architecture. Taking into account the existing warehousing system requirements, the basic functions of the automated warehousing system are as follows: First, real-time cargo location query: By scanning the barcode of the product, you can query its storage location in real time, and query the product information based on the cargo location inventory information. Second, dynamic and comprehensive allocation of human and material resources: human and material resources can be dynamically allocated based on the batches of goods entering and leaving the warehouse, thereby improving the operating efficiency of the system and reducing waste of resources. Third, the comprehensive inventory function of the warehouse system: the entire warehouse system can be regularly inventoried and a difference table can be generated to facilitate re-inventory verification. Fourth, the random inventory function within the warehouse: random inspections can be conducted by warehouse, partition, and cargo location, or inspections can be conducted on specific types of goods. Fifth, the internal data query function of the associated customer: real-time query of product information through product codes to check whether the information on the product is consistent with the system. Sixth, the temporary sales function: during the peak sales period during holidays, the RF terminal can be used as a POS machine to relieve the pressure on customers to check out at the cash register when selling.

The establishment of the system must meet the following conditions: Real-time data collection: Due to the mobility of personnel operations, wireless network technology and wireless handheld computer terminals must be used. Commodity barcoding: Barcodes are the unique identification of commodities. The basis of modern commercial management (including warehouse management) is the barcoding of commodities. At present, my country has corresponding barcode management standards, but it is also necessary to comprehensively select appropriate barcode standards in combination with international practices. This is the basis for implementing barcode management. Standardization and barcoding of cargo locations: Automated warehouse management must use barcode technology to establish standardized cargo location management.

System network structure design: 1. Use RF technology. RF (radio frequency) technology uses wireless channels as transmission media, has rapid network construction and flexible communication, and can provide users with fast, convenient and real-time network connections. It is one of the key technologies for realizing mobile communications. At present, the application of RF technology has penetrated into many fields such as commerce, industry, transportation, logistics management, medical insurance, finance and teaching. With the growing demand for wireless computer local area networks based on RF technology, the American Institute of Electrical and Electronics Engineers (IEEE) officially announced the computer wireless network communication standard - IEEE802.11 standard in June 1997. With the formulation and implementation of this standard, wireless local area network products will be more abundant and the compatibility of different products will be enhanced. At present, the global wireless RF spread spectrum technology mainly includes the direct sequence spread spectrum (DSSS) technology of code division multiple access CDMA and the frequency hopping spread spectrum (FHSS) technology. The IEEE802.11 standard supports both technologies. From a technical perspective, direct spread technology and frequency hopping technology each have their own advantages. In terms of frequency band utilization, direct spread technology adopts the active occupation method, while frequency hopping is to hop and change the frequency to adapt. In terms of their respective technical characteristics, in terms of the limit rate, direct spread technology can reach more than 10Mbps, while frequency hopping can only support about 3Mbps. In terms of anti-interference, frequency hopping technology is better than direct spread technology. For large-scale warehouse management systems, the transmission rate is more important than the anti-interference requirement. At the same time, the direct expansion technology can fully meet the anti-interference factor of wireless signals. As far as we know, the design of large-scale warehouse supermarket storage systems has chosen wireless RF products based on direct expansion technology. 2. System network topology. According to different application environments, the topology structures currently used by wireless LANs are mainly bridge connection type, access node connection type, HUB access type and centerless type. The application of automated warehouse management system is based on centralized service. In view of the needs of warehouse management, there is no need for communication between mobile nodes. As the internal logistics center, the wireless RF network topology designed is access node connection type. The operation area of RF mobile terminals covers every corner of the store, requiring mobile terminals to maintain real-time communication with the server host at any location inside the warehouse. Therefore, in the system network architecture, it must be ensured that the installed AP point (ACCESS POINT) can fully cover the entire warehouse with wireless signals. If the warehouse area is large, when designing the wireless network, you can make full use of the network expansion capability and seamless roaming characteristics of wireless RF technology to combine multiple AP points for the wireless signal of the warehouse, that is, by setting up multiple AP nodes, you can achieve full signal coverage, and the adjacent APs cover each other to improve the reliability of the wireless network. At the same time, considering that the office area of a large storage warehouse may not be in the same area as the storage area, and it is inconvenient to use a wired network connection, a wireless bridge can be used between the storage and office areas to make it a unified network system, which is convenient for network expansion and removal. The through-type warehouse mainly for distribution can be designed according to this model. 3. RF handheld data acquisition terminal. The selection of RF handheld data acquisition terminal (built-in laser barcode scanner) is mainly based on the following four points: one is the transmission rate; the second is anti-interference; the third is compatibility; and the fourth is future upgradeability and scalability. Under the condition of a relatively simple electromagnetic environment, Jiashijie chose the RF handheld data acquisition terminal using direct expansion technology to maximize the real-time needs of the system. At the same time, it is noted that the RF handheld data acquisition terminal must comply with the IEEE802.11 protocol standard to meet the compatibility requirements. Considering the performance and price factors of RF handheld terminals, a product with a modular design structure was selected to facilitate future technology upgrades and expansions. If the logistics center is a large supermarket or provides distribution services in the urban area, the above technical factors should also be taken into account.

System software design and implementation System development mode: There are three main development modes for RF handheld data acquisition terminals: (1) Based on Telnet structure: The RF handheld terminal (built-in Telnet Client, i.e., emulation terminal) remotely logs in to the host server (running Telnet Server), runs the warehouse data acquisition software on the host server, and directly stores the collected data in the database in real time. The query results are returned to the RF handheld terminal for display; (2) Client/Server (C/S) structure: The warehouse management server software runs on the host server, and the corresponding warehouse data acquisition client software runs on the RF handheld terminal; (3) Based on WEB structure: The WWW server and warehouse management application service software run on the host server, and the embedded browser runs on the RF handheld terminal. Among the above three methods, the advantage of the Telnet structure is that it can make full use of the processing power of the host server and has a relatively simple structure; the client/server (C/S) structure has high requirements for the processing power of the RF handheld terminal, and from the programming perspective, it has a strong dependence on the development tools provided by the manufacturer; the advantage of the WEB structure is that programming and maintenance are simple, and development is concentrated on the server side, but the input and display configuration requirements of the RF handheld terminal are relatively high. Therefore, in order to facilitate future expansion and transplantation of applications, the Telnet structure-based method is selected for software development. At the same time, combined with the geographic information system GIS technology, this method of developing a WWW-based cargo location information query system on the server side is an ideal choice.

System software development The software configuration of the wireless system is as follows: (1) System host server software: UNIX and Windows NT operating systems each have their own advantages. Windows NT is easy to maintain, and UNIX can support more RF handheld terminals, but it has higher requirements for customer system technical maintenance personnel. Since the system requires that the number of RF handheld terminals supported is less than 50, Windows NT 2000 Advanced Server is selected as the operating system of the system host server, Microsoft SQL Server 2000 is selected as the system database, UNIX for Windows NT 2000 is selected as the Telnet Server, and IIS is selected as the Web Server. (2) Warehouse management system software: This software is divided into two parts. One is the server software used for warehouse management services, statistics, etc., and the other is the functional module Telnet client software that runs after the RF handheld terminal logs in. This system uses Delphi 5.0 and C++ Builder 5.0 development language, the server software RF Warehouse2000 that realizes warehouse management services, statistics and other functions, and the functional module client software RF Warehouse Client2000 that runs after the RF handheld terminal logs in are both developed using the C/S structure. In order to improve the database access speed and handle data conflicts, the stored procedure and trigger mechanism are used for database operations. The cargo location query system is based on the B/S structure, and the development language overcomes the problem of insufficient ASP running speed. At the same time, the concept of geographic information system GIS is applied, and JAVA is used to realize the graphical visualization query of cargo locations. The implementation of the wireless real-time warehouse management system can greatly improve the efficiency of the operation and management of the warehouse-type logistics center, greatly reduce the time for finding cargo location information in the existing model (it can be shortened by about 2/3 after testing), improve the accuracy of query and inventory (the accuracy can reach more than 99%), and greatly speed up the circulation of goods. At the same time, the implementation of the system also reduces the waste of human resources and improves the utilization rate of personnel. Through use, the confidence of the warehousing industry in using wireless equipment can be enhanced, and at the same time, the order and receipt functions should be developed to give full play to the efficiency of the use of RF terminals.