Setting AGVs free

26 February 2018

Marco Reichenbächer explains how AGVs can be freed from their traditional guidance system limitations through the use of wireless communication technology.

Many manufacturers are embracing a new era in communication by employing automation equipment with wireless communication technologies to increase productivity. The digitalisation of these systems can bring a new level of control to industrial communication across all industries. F

or an additional level of improved operational performance and connectivity some industry sectors are also seeking to equip their facilities with automated guided vehicles (AVGs) – mobile vehicles, commonly referred to as robots, that rely on wires and cabling or sensors and wireless technologies for navigation within industrial settings – to move materials around a facility.

The latest trend in AGVs is the shift to autonomous vehicles that tap into wireless technology. One European- AGV manufacturer sought to integrate best-in-market wireless solutions into its AGVs to provide its customers with long-term cost savings, reduced errors and improved process optimisation. ??

To wireless AGV communication solution needed to be able to ensure reliable and sound wireless speed. Specific system requirements included:?

• Reliable and stable wireless roaming capabilities with low handover times (in the milliseconds) to keep the AGVs moving on the planned schedule and avoid delays.
• The use of limited frequency bandwidth. For example, a client device with 2.4 and 5 GHz bands can limit interference problems by using multiple frequencies to support simultaneous customer requests through the same client.
• A variety of security options to protect the wireless communication from internal and external threats. This could be achieved by using Wi-Fi security algorithms, like Wi-Fi Protected Access (WPA2), Wireless Intrusion Detection System (WIDS) or Rogue Client Detection.
• High-speed wireless connections that are stable enough to overcome common interferences, such as industrial metal surfaces causing reflection of radio waves.
• Stress-resistant components that can hold up in the common environmental conditions that commonly affect AGVs, such as constant vibration, condensation, or temperature extremes.
• Future proofed with latest IEEE 802.11n/ac wireless standard and multiple input, multiple output (MIMO) antenna technology.

Beyond expectations
This particular AGV manufacturer needed a robust and cost-effective wireless solution that would meet the needs of its mobile vehicles. The manufacturer gravitated toward two types of solutions to ensure reliable communication coverage – an industrial wireless access point/client and an omnidirectional antenna. The wireless access point solved a critical concern of providing secure Wi-Fi communication, while maintaining a short roaming handover time. The access points used the latest WPA2 enterprise (IEEE 802.11i/IEEE 802.1x) in combination with Opportunistic Key Caching (OKC) to guarantee the highest of level of wireless security and improve roaming handover time.

When OKC was used in coordination with a central wireless local area network (WLAN), the manufacturer could deliver fast authentication between multiple access points throughout a network. Once set up with a WLAN, OKC helped establish an uninterrupted supply of communication, or fast roaming. This capability – which is now minimised to just milliseconds – is measured by the handover time between access points.

The benefits of using a wireless access point and client which were critical to the manufacturer’s choice in delivering optimised operation and error reduction throughout their networks include:?

• High data transfer speeds, ideally up to 867 Mbit/s and meets IEEE 802.11n/ac standard for network speed.
• Low signal interference, meeting the challenging requirements of industrial markets, including vibrations and EMC.
• High system reliability with expanded management, redundancy and security functions with specialised operating systems
• Boosted warehouse efficiency through better WLAN roaming for moving vehicles
• Better machine uptime and easier AGV fleet scalability due to fast wireless set up, centralised setting changes and updates
• Lower complexity and installation time with less frequency of AGV planning via 2.4 and 5 GHz bands, providing more non-overlapping channels

All manufacturing environments will pose unique challenges for automation teams beyond the traditional concerns of increased uptime, productivity and operational efficiency. In this application the manufacturer selected omnidirectional antennas to work with the wireless access point and client to provide the AGVs with a full range of connectivity within their harsh operating environments.

The antenna complied with the Ingress Protection (IP) 65 degree of protection for high industrial suitability and improved transmit-and-receive power through the homogenous emission behaviour of the antennas during operation. The N sockets allowed the team to connect the antennas easily and quickly with other cables and overvoltage protectors. In this case, the antenna enabled the network to operate reliably due to its sturdy, vibration-resistant and weatherproof design.

Once installed end-users of the AGVs are now able to replicate the IP configuration from one AGV to the rest of their fleets by using the NAT feature on the wireless client. Through reduced installation costs and complexity, end users are now equipped with the means to expand their fleets with improved Wi-Fi density for disruption-free signals.

By applying wireless communication applications directly to mobile vehicles, companies are able to reduce the amount of magnetic tape guidance systems in the ground throughout the factory floor. This increases route flexibility and reduces installation costs and the need for regular maintenance. Instead, companies can replace physical components with a reliable, efficient and up-to-date means to control AGV communication.

The expansion of industrial digitalisation is not an industry update – it’s a wholesale shift. The trend towards highly flexible production areas – or without fixed and predefined production sequences – throughout the smart factory is coming. As the supply and installation of self-autonomic production lines expands, end users will look to industry innovators for the next generation of network components for reliable and disruption-free wireless communication.

Marco Reichenbächer is senior vertical marketing manager for Automotive Manufacturing at Belden Inc.

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