For Zhao Ming, who is in charge of IT operation and maintenance in an e-commerce company's warehouse center of more than 100,000 square meters, the annual 618 and Singles' Day sales season is a tough battle: In order to improve the efficiency of goods selection, the company introduced AGV unmanned vehicle for goods handling in the first two years, although the robot handling efficiency is much higher than manual, but in the process of handling often because of network problems AGV "down", which makes Zhao Ming have to tighten his nerves.
However, the number of goods handled at the warehouse increased by 30 percent on Nov 11, 2020, and Zhao said he felt much more relaxed during what should have been a new round of sleepless nights. This is not because the operation and maintenance department has increased the manpower, but because the warehouse center just deployed the wireless zero roaming solution of Ruijie Industry at the end of October, which dramatically reduced the packet loss rate of wireless AP roaming from the original 2% to less than one thousand. Meanwhile, the average roaming delay is less than 10ms, and the AGV unmanned vehicle has been completely cured due to the "collapse" of the network.
Behind the 20-fold reduction in roaming packet loss rate is the continuous accumulation of the R&D team of Ruijie for 20 years and the continuous innovation in the industrial wireless zero roaming scene.
Start with the frequent failures of unmanned AGV vehicles
Speaking of wireless network roaming, I believe many office workers have experience. When connecting to Wi-Fi in the office area, it is common to experience a sudden "lag" when crossing different AP coverage areas. This is due to the problems of high delay jitter and packet loss during roaming switch of the wireless network.
The same problem exists in the AGV application scenario, but the problem is much more serious. For ordinary people, the "lag" in wireless network roaming can be solved only by walking a few more steps or waiting a few seconds, and generally will not bring any loss. However, in working environments such as warehousing and workshops, critical information and instructions such as "where I am, where I am going, and how to get there" of AGVs need to be transmitted and received through the network. However, once the network packet loss rate of more than 1/1000 occurs in the fast moving process of AGVs, some devices may lose contact or stop responding, resulting in service interruption.
With the rise of intelligent manufacturing and intelligent logistics, AGV unmanned vehicles have been more and more widely used, and the phenomenon of frequent "off chain" of AGVs has become increasingly prominent.
After understanding the demand pain points of manufacturing, e-commerce and other industry customers feedback, Ruijie network R & D personnel through repeated field survey, they found that this problem is not so easy to solve as expected.
On the one hand, in practical application scenarios such as factories and warehousing, a large number of metal shelves and metal production equipment stand in great abundance, and the goods corridor is narrow. The steel jungle of modern industry and a large number of electronic equipment will have very serious interference on Wi-Fi signal transmission. On the other hand, different types and brands of AGVs are often deployed in different factories or storage centers. These AGVs vary widely in terms of network compatibility and network performance. If hardware adaptation and performance tuning are only carried out for certain types of AGVs, Such a wireless zero roaming solution is likely to have a very low roaming packet loss rate of local AGV devices and a good application effect, but the roaming packet loss rate of other AGV devices increases sharply.
AGV car networking principle
In addition to AGVs, PDA scanner and other wireless networking devices widely used in the production environment of e-commerce and logistics enterprises also need to be frequently used across AP areas, which also has high requirements for wireless network roaming quality.
In order to solve this intractable problem, some industry manufacturers have launched an overall optimization scheme, but this scheme often needs to cooperate with specific network adapters and plug-ins to achieve lossless roaming, and the actual network packet loss rate is still as high as 0.5%-1%, which is difficult to meet the AGV network roaming packet loss rate
"At present, other domestic manufacturers have not really reached the AGV car network quality index requirements, this is a challenge to the industry, but also Ruijie network bounden responsibility!" Responsible for industrial wireless zero roaming solution product manager Ye Zuxin stressed.
Based on scene innovation, Ruijie ingenuity to create industrial wireless zero roaming solutions
After the sharp capture of user needs, Ruijie, relying on the deep accumulation in wireless network technology, set up an industrial wireless zero roaming research and development team, using TRIZ problem-solving tools and methods, through the establishment and analysis of system function model, causal chain analysis, and the application of conflict resolution theory tools, found the corresponding invention principle solution. And transform into industrial wireless zero roaming solution practical application.
After repeated demonstration, Ruijie Industry wireless zero roaming solution development team found that starting from the wireless network scheduling management mode, rather than making major changes at the hardware level, can help reduce the application threshold of the solution, and can simplify deployment. Based on this conclusion, the R&D team obtained the optimal solution of "BSSID follow +BSS pre-migration + dynamic threshold decision algorithm" to optimize the reassociation time during AP switching and realize AC switching according to the current signal dynamic state of the device.
"The establishment of the optimal solution of network technology is crucial for industrial wireless zero roaming, but it does not mean that we can solve the problem overnight. In fact, the greater challenge lies in continuous optimization and verification for practical application scenarios, "Ye pointed out." Most customers' AGVs, PDAs and network deployment environments vary greatly, so a solution for a single environment verification cannot be applied everywhere, which requires repeated testing. To address the potential loopholes and problems in the program."
In order to verify various possible situations, the partners of the industrial wireless zero roaming research and development team often have to walk back and forth in the warehouse of tens of thousands of square meters for several hours, and the "step number" is often as high as 40,000 to 50,000 steps every day. During that time, the research and development Tan Gong, who is famous for his "house", realized the comprehensive "top bang" of the "wechat movement", and even attracted the "small storm" of the family: in order to reduce the disturbance to customers, he could only go to the scene "strolling" after work at ten o 'clock in the evening, and "stay home" and "run around at night" for several weeks, which was simply "beautiful"...
Optimization results of Ruijie industrial wireless zero roaming solution
After half a year of hard work, the R&D team finally harvested the expected results: After the deployment of Ruijie industrial wireless zero roaming solution, the roaming packet loss rate of wireless network is reduced from the original 2% to 0.1%, and the average roaming delay is less than 10ms, which perfectly realizes the "true wireless zero roaming" under the fast movement of wireless devices such as AGV cars and PDA.
Customer recognition is the best commendation for "50,000 steps a day"
At present, in Fuzhou Jingxi Wanquan distribution center, Xiamen strong Jucai optical, Jiangsu Qunli, Datarai robot, Jiuzhou Tong Warehouse and other customers in the actual production environment, Rui Jie industrial wireless zero roaming solutions have been successfully applied, in the real scene to achieve less than one thousand roaming packet loss rate, wireless network quality has been comprehensively improved.
Back to the beginning of the article, Zhao Ming, the IT operation and maintenance supervisor of the warehouse center, was deeply impressed by the transformation after the deployment of Ruijie solution. "Thanks to the joint efforts of Ruijie network R&D, testing and implementation personnel, after the deployment of Ruijie industrial wireless zero roaming solution, our AGVs and PDAs roaming among multiple aps in the warehouse never appeared packet loss. At the moving speed of 2~3m/s, the AGV car runs stably, without delay and without interruption. At the same time, the stable return result greatly reduces our operation and maintenance work burden. It is estimated that the working efficiency of warehouse centers has increased by a full 40 percent during the Nov 11 holiday.
In a short period of 8 months to create such a "unique" industrial wireless zero roaming solution, Ye Zuxin said in summarizing the research and development experience, "Through the collaborative efforts of the team and the application of TRIZ tool, we found that scene innovation needs to start from more user scenarios, redefine the problem and solution, and find the optimal solution. And from the program evaluation quickly market value verification, to achieve continuous grinding and improvement of products, to bring greater value to customers."
