This is a real-life case study. However the customer has chosen not to feature their brand name.

In a super-modern automotive factory in Germany, automated guided vehicles – AGVs – handle the transportation of automotive parts from the loading dock to the assembly line.

Everything from heavy engines to steering wheels and smaller electronics are loaded on to the AGVs, which often consist of several wagons, and transported out to different parts of the factory.

The distance varies from 300 to 800 meters and the transport is completely automatic with no human drivers involved. 

To enable the AGVs to find their way, a lot of communication is needed between the AGVs and the factory’s control system – The factory needs to know at any given moment, where every AGV is, what it is carrying, and what its status is.

Since cabling would be impossible for this type of solution, the automotive factory found the Anybus Wireless offering from HMS Networks. 

Mr. Maximilian Lichan, M.Sc. Dipl. Ing. (FH) explains: “We were using another wireless solution previously, but it used manual roaming via openTCP and we had trouble when the AGVs need to switch from one access point to another. We looked into another solution and  came across the Anybus Wireless products. Our need was a stable radio link and secure connection to our main controller.”

How it works — Modbus-TCP over Bluetooth 

About 40 AGVs move around the factory. Each AGV is controlled by an on-board Programmable Logic Controller (PLC) from Siemens or Schneider Electric. The PLC makes sure each AGV gets to the right location and don’t run into another AGV. The communication protocol used is Modbus-TCP. 

To handle the communication from the AGVs to the traffic control system, an Anybus Wireless Bolt is mounted on each AGV (just like a bolt). The Wireless Bolts connect to about 30 different access points (Anybus Wireless Bridges) in the ceiling of the factory. Whenever an AGV travels out-of-range of one access point, it switches to the next. This feature — automatic roaming — has been greatly beneficial for the factory. 

The Anybus Wireless Bolt is connected to the AGV and communicates via Bluetooth to an Anybus Wireless Bridge in the ceiling of the factory. Data exchange includes position, cargo, energy levels etc. 

The results

”We have seen many benefits with switching to Anybus Wireless explains," Maximilian Lichan. “Firstly, the Bluetooth communication is very stable. Industrial conditions are challenging for wireless communication but the Anybus Wireless Bolt and Bridge have an extremely reliable and robust radio connection which can also be set up quickly and easily. There is also a very good coexistence with the Wi-Fi network in the factory.”

Another benefit is that it is easy to introduce a new unit or exchange a damaged one. Recently, one of the Bolts were damaged at the loading dock. But it could be quickly replaced with a new one and the AGV could be back in operation shortly – extremely important in the well-planned workflow of a car factory.

A demanding implementation

The wireless communication in the automotive factory is now running smoothly, but the implementation process had its fair share of challenges. The factory were early adopters of the new Anybus Wireless Bolt and struggled with roaming and stability, but with support from HMS, the solution fell well into place.

“I must say that the support from HMS was great and we were able to solve the problems together. Now we have an application that we are very satisfied with,” says Maximilian Lichan. 

Finally, What are your tips to users who are thinking of going wireless?

“These Anybus Wireless devices using Bluetooth are well-suited for applications that need to exchange data wirelessly, where the speed and data volume of the connection is secondary and stability is more important.” 

Safety first. Not only do the AGVs find their way, they also need to cater for people walking in the corridors and other AGVs in the car factory. Therefore, they are equipped with a laser sensor in the front stopping them if anything comes in the way.