Wireless technology enables AGVs to increase production efficiency

A Swedish manufacturer of heavy vehicle components wanted to eliminate manual and heavy lifting processes within its production lines, and tasked Swedish Löfqvist Engineering with designing and implementing a new automated solution for its large production area.

The solution involved the manufacturer’s existing machine centres, which performed all production functions such as turning, reaming and hardening. These were being replaced by eight automated, function-specific production cells that produce the various vehicle components. Critical to the project was the integration of these production cells, and the efficient movement of components between the cells, and in and out of the production facility.

This labour-intensive task had previously been performed manually, which involved much heavy lifting and was inefficient. The manufacturer initially considered fixed conveyor belts, but concluded that AGVs would be a more productive solution that would also provide greater flexibility when adapting to changing production demands.

Löfqvist Engineering developed and implemented three AGVs to move specific components to the appropriate production cells, while a fourth was fitted with a mobile cobot to perform quality checks on the parts. Because the AGVs move freely between the production cells to supply and collect components as required, reliable wireless communication is essential.

Löfqvist Engineering has a long and trusted relationship with HMS Networks, and opted to implement an Anybus wireless communication solution for this new production system. HMS Networks engineers supported Löfqvist Engineering in implementing the solution, which included mounting two Anybus Wireless Bolt devices on each of the AGVs to enable connection to a wireless network via Bluetooth or Wireless LAN.

A Wireless Bolt is a compact, all-in-one package that features a connector, communication processor and integrated antenna in the same unit, with IP67 protection. Because of the limited space available on the AGVs, this compact form factor was critical. One Wireless Bolt is connected to an onboard Omron PLC (that manages the AGV’s movement and safety functions) and provides communication with a central supervisory PLC system.

The second Wireless Bolt is connected to the AGV’s robot controller and provides wireless access to remotely configure or troubleshoot the AGVs via a browser on a handheld device.

Because the manufacturer’s overall production area is so large, the solution required three Anybus Wireless Access Points (APs). These industrial-grade infrastructure hubs are installed at strategic points to form the wireless network and ensure an overlapping coverage area that facilitates roaming.

The Anybus devices support the IEEE 802.11r standard for fast roaming within a wireless network. This is useful for applications involving AGVs, where seamless connectivity is required across the entire factory floor to ensure that the AGVs are always in contact with the network.

Wireless roaming is when a client device moves around in an area with multiple APs and may automatically switch from one AP to another that has a stronger signal. Without fast roaming support, that transition would require the client to re-authenticate. As a result, there could be a delay and loss of connection, which could trip an emergency stop, thereby impacting production efficiency.

However, with fast roaming, client devices are authenticated to the first AP and their credentials are forwarded to the next AP prior to roaming, which eliminates the need for re-authentication. This significantly reduces the handover time, while still maintaining network security.

“The factory floor is a tough and demanding industrial environment, so it was essential for us to develop a robust communications network with good functionality,” said Anders Unefäldt of Löfqvist Engineering, “The rugged design and high reliability of the Wireless Bolts and APs used in the HMS Networks Anybus solution was ideal in meeting our requirements.”

The supporting wireless network infrastructure also uses an Anybus X-gateway to provide seamless communications between the onboard and supervisory PLCs. Because the AGVs employ automation technology from different vendors, this created a situation where different data communication protocols were used.

For example, the Omron PLC that uses EtherNet/IP communications over the wireless network needs to connect to a Siemens supervisory system that uses Profinet communications. The Anybus X-gateway simplifies this multi-vendor PLC solution by translating between EtherNet/IP and Profinet.

The AGVs are operating almost continuously, which has enabled the manufacturer to increase production to 5000 units a week, with spare capacity available to support future growth.