Waveguide is a structure used to directionally guide electromagnetic waves. It is a hollow metal tube with a very smooth inner wall or a tube lined with metal, which is used to transmit ultra-high frequency electromagnetic waves, allowing pulse signals to be transmitted to the destination with minimal loss. For basic knowledge about waveguides and their communication, please refer to the article A Brief Analysis of Waveguide Communication Technology and Applications in the “Technical Support” section on the official website of Guoxin Longxin Technology (http://www.gliii.com). This article aims to explore the application issues and prospects of waveguide communication technology in the field of intelligent control of heavy machinery (cranes), including scenarios such as remote manual control, mechanical automatic driving, and AI intelligent production.

The waveguides referred to in this article mainly refer to slotted waveguides. Due to the high price of copper, aluminum is relatively cheaper and easier to process and transport. Therefore, at present, aluminum alloy is the most commonly used material for slotted waveguides, and rectangular aluminum alloy waveguides are most commonly used in conjunction with the iMAX wireless system.

I. Why is waveguide communication system used for crane intelligent control?

Waveguide communication is very suitable for various application scenarios of crane intelligent control, for the following reasons:

First, contactless communication: Since the cranes that need communication are mobile, if wired methods such as optical fibers (used with drag chains or hinges) are adopted, the optical fibers are prone to breakage and fatigue in mobile scenarios, resulting in low reliability and short service life, while the cost and maintenance are very high. Therefore, wireless communication is the first choice. Waveguide wireless communication is a contactless communication method, so it avoids the problems of fatigue and breakage caused by wired curling and dragging, making it an ideal networking method for linear reciprocating movement.

By the way: Optical fiber is actually a kind of “waveguide”, a fiber made of glass or plastic. At present, the most commonly used optical fibers are multimode fibers, with core diameters of 50μm and 62.5μm, which are roughly equivalent to the thickness of human hair; the core diameter of single-mode fibers is 8μm~10μm, and the commonly used one is 9/125μm. Light is a kind of electromagnetic wave, and the commonly used light wavelengths in optical fibers are 850nm, 1310nm, and 1550nm. That is to say, optical fibers are very thin, and physical operations such as bending, curling, and stretching will cause fatigue damage to them, or even direct breakage.

Second, strong anti-interference characteristics: One of the most common problems in radio communication is electromagnetic interference, which is generally referred to as “co-channel interference” and “adjacent channel interference” in the field of wireless communication. Due to its system design that makes good use of the principles of electrostatic shielding and total reflection, the waveguide ensures the transmission quality of radio signals in the cavity, thereby guaranteeing the stability and reliability of the communication system. The communication distance between the slotted waveguide and the crane-mounted antenna is generally 20-30 centimeters, which can effectively reduce the impact of external radio interference and ensure the bandwidth capacity and stability of the link.

By the way: From the perspective of wireless communication, the simplest and most direct solution to interference is frequency avoidance, that is, using a “clean frequency”. The iMAX wireless system of Guoxin Longxin supports a 5GHz wideband design, so there are many optional frequencies. Generally, the interference problem can be solved by changing the working frequency. For scenarios with extremely strong interference where all working frequencies are affected, the equipment of some professional wireless communication system manufacturers, such as the iMAX wireless private network system of Guoxin Longxin, can enable a proprietary “anti-interference mode” to reduce the impact of interference and ensure the stability of the system. However, the cost may be a significant sacrifice of effective bandwidth. Fundamentally speaking, waveguide communication is the best means to solve the interference problem and ensure the stability of wireless communication. For the problem of radio interference, please refer to the article How to Solve Wireless Interference?

Third, high bandwidth and low latency: Due to the excellent transmission characteristics of the slotted waveguide, the latency of the waveguide wireless network is greatly reduced, and the packet loss rate is also significantly lower than that of pure air interface wireless communication. From the perspective of ensuring communication stability, communication means similar to waveguides include leaky wave cables. However, due to the technical limitations of leaky wave cables, they are usually used for narrowband communication with low bandwidth (switching and analog information). Crane intelligent control requires high bandwidth, large-capacity high-definition video, and low-latency transmission, which can only be met by waveguide communication systems.

In summary, crane intelligent control is a typical scenario with high reliability, high bandwidth, and high capacity requirements, namely “three-high communication”. At the same time, it must also meet the high standards of “three-low communication” with low latency, low failure rate, and low power consumption. Therefore, the most suitable communication means is the waveguide communication system. It can be said that in the scenario of crane intelligent control, the reliability, stability, and cost-effectiveness of the waveguide communication system are far higher than those of optical cables.

II. Which heavy machinery intelligent control scenarios are suitable for waveguide communication?

Traditionally, the most common application scenario of waveguide communication is rail transit, and its application in fields such as metro train-ground communication has become one of the mainstream solutions. In recent years, industries such as ports, logistics, shipbuilding, steel, chemicals, aerospace, military industry, and other industrial productions are undergoing a vigorous intelligent revolution. As for industrial production, especially heavy industries like ports, logistics, and shipbuilding, cranes are indispensable and most commonly used equipment. Only when these heavy machinery realize “automatic driving” can the production landscape of these industries undergo significant changes. Since it involves control, especially the automatic control of heavy machinery and equipment, if there is a problem with communication, it may greatly reduce work efficiency and even lead to safety accidents. Therefore, the most reliable solution is necessary, which is where the prospect of the waveguide communication system lies.

As a wireless communication system supporting automatic driving, remote control, or intelligent control of heavy machinery, it must have high reliability and stability. If high-definition video transmission is involved, it must also have high performance and high bandwidth. This is actually the fundamental reason why many new partners of Guoxin Longxin have approached Guoxin Loongson to provide wireless systems in recent years.

Then, in which intelligent control scenarios of heavy machinery and equipment will the waveguide communication system be used?

The most common ones are the traveling cranes commonly seen in industrial sites, as well as quay cranes, gantry cranes, RTGs (Rubber-Tired Gantry Cranes), RMGs (Rail-Mounted Gantry Cranes), portal cranes, etc. The reliability of the waveguide communication system used in the intelligent control of these cranes is far higher than that of optical cable systems.

In similar scenarios, not only are the “three high characteristics” of systems like the iMAX wireless private network required, but also strong comprehensive capabilities in technical design and solution provision, as well as high requirements for after-sales service. These are precisely the core competencies of Guoxin Longxin, which will not be elaborated on in this article.

To sum up, due to the excellent anti-interference ability of waveguides, they have become the best networking solution in crane remote control and intelligent control applications in certain scenarios. For example, traveling cranes used in electrolytic aluminum plants, copper smelters, steel mills, power plants, and machine processing factories; and RTGs (Rubber-Tired Gantries), RMGs (Rail-Mounted Gantries), and quay cranes in ports and logistics yards, etc.

III. Considerations for Waveguide Communication System Solutions

1. Redundant hot standby design: Similar to towed optical cables, when the waveguide wireless communication system is used as a single communication system in actual networking, redundant hot standby design must be implemented in the network structure to ensure system reliability. The most common high-reliability technologies are VRRP (Virtual Router Redundancy Protocol) virtual hot standby routing and multi-link data mirroring technology. For specific technologies, please refer to the article How to Ensure the Reliability of Wireless Network Communication Systems?

It must be emphasized that ordinary wireless WiFi systems (including wireless bridges) do not support professional-grade routing technologies. When using wireless bridges for hot standby and ring networks, difficult problems such as failure to disconnect during switching and inability to connect to roaming base stations are often encountered, and some cannot even be solved at all. For details on the routing technology of Guoxin Longxin’s wireless systems, please refer to the article How Important is it for Wireless Systems to Support Routing Technology?

2. Length of waveguides: In the design of waveguide communication solutions for intelligent control of heavy machinery, full consideration should be given to the transmission distance limitation of waveguides, and the design must be based on the length of the movement route of on-site heavy machinery. In addition, different crane intelligent control scenarios have different bandwidth requirements. Therefore, it is necessary to deploy a waveguide system of appropriate length on the basis of ensuring sufficient bandwidth in combination with actual needs.

3. Mobility and roaming features: For long activity areas and travel routes, multiple sets of waveguide systems need to be connected end to end in a relay mode. Cranes need to move and roam at high speed between multiple waveguide base stations, which is also a key consideration in the design. The equipment and antennas configured for the waveguide communication terminal devices on cranes are very important; even the distance between the antenna and the waveguide is a very rigorous technical issue. If the configuration is inappropriate, it may, at best, affect the usage effect, or at worst, directly lead to collision and damage accidents.

In summary, the waveguide communication system is a highly customized system. Guoxin Longxin has increasingly rich experience in the application of waveguide wireless communication systems, which is crucial to the success or failure of intelligent control systems for heavy machinery. For project examples, please refer to Case Sharing on Intelligent Remote Control and Unmanned Operation of Heavy Machinery 2023.

Guoxin Longxin also has a series of innovations targeting waveguide applications. For example, it has innovatively launched a dual-mode waveguide on-board terminal, which can connect to two front and rear waveguide base stations (BS) simultaneously. This improves the speed of service roaming, shortens the handover time, and can even achieve uninterrupted “zero packet loss roaming”. This is attributed to Guoxin Longxin’s continuous application exploration and technological innovation. There are numerous similar innovations, making Guoxin Longxin a leader in the field of waveguide communication applications for intelligent control of heavy machinery.

IV. What are the limitations of using waveguide communication systems?

There is no perfect technology in the world, and waveguide communication systems also have limitations in use:

1. Linear reciprocating movement: One of the biggest issues with waveguide communication systems is that they can only be used for communication with moving objects traveling on “fixed tracks”. Moreover, scenarios such as transferring from one track to another still require the assistance of pure wireless communication systems.

2. Deployment spacing: Due to factors such as design and manufacturing, waveguide communication systems have detailed requirements for the communication distance, angle, etc., between the waveguide antenna and the waveguide. This also places demands on the on-site deployment of waveguides, which must be met.

3. Installation and environment: The waveguide itself has a relatively high cost, mainly because it is a customized product that must be designed according to different frequencies, application environments, etc. The installation requirements are also high; there are technical specifications for the levelness, verticality of installation, and the precision of butt joints. The cavity needs to be cleaned, and may require sealing after being filled with nitrogen to prevent dust and water vapor from entering and condensing, among other things.

As the automation and intelligent applications of heavy machinery and equipment become increasingly popular, the demand for waveguide communication systems will grow. Guoxin Longxin’s iMAX-8000W series of dedicated mobile communication systems for waveguides is currently one of the pioneers in the application of waveguide communication in the field of “unmanned driving” for domestic heavy machinery, with broad application prospects.

Continuous innovation and evolution to meet users’ needs for high-quality and high-performance communication in harsh environments are the driving forces behind Guoxin Longxin’s commitment to innovation. For partners with demands for high-reliability networking for crane intelligent control, they can provide technical details of specific requirements, and we will design waveguide solutions based on these needs.