Robot positioning at VW Sachsen GmbH

Until a few years ago, robot positioning using industrial image processing systems could only be achieved through complex and costly PC-based systems. However, image processing sensors are increasingly being used even in this technically demanding area of industrial image processing.

The Mosel plant, which belongs to Volkswagen Sachsen GmbH, employs 6,200 people and has a capacity of approximately 1,150 vehicles per day, making it one of the most advanced automobile factories in Europe. Since 1990 over 2 million Golfs and Passat saloons have been produced at Mosel. Below are some robot positioning applications which have been produced by our systems partner “Schönherr Electronik” at the Mosel plant in the last few years.

Robot control in the sealing of engine bulkhead panels in Passat saloons

In Hall 3 at the “engine bulkhead sealing” station (this bulkhead is a panel which separates the engine compartment from the vehicle cockpit), a Fanuc robot applies the sealant to the welds of the bulkhead using the flatstream process. This process differs from the spray technology previously used in that there is significantly less overspray.

The process is as follows: the EDP-coated car bodies arrive at the station by means of an overhead carrier system and are then positioned at the station by means of a lifting platform. Subsequently, the positions of 3 car body features are determined. This task is performed by three intelligent vision sensors from Omron installed in the station. The co-ordinates are passed by a controller to a PLC where the data is prepared and forwarded to the Fanuc robot controller. On the basis of the values that are calculated from this, the robot brings the spray head into the correct position and starts to apply the sealant.

Robot control for the underseal of the Passat saloon and the new Golf

Before being painted, the EDP-coated Golf and Passat saloon car bodies pass through the UBS stations on lines 1 and 2 where all the welds of the car underbody and the wheel arches are sealed, in each case by two Fanuc robots using the flatstream process. Here also the car bodies arrive at the UBS stations by means of an overhead carrier system. In each case, three intelligent vision sensors determine the co-ordinates of three vehicle features and transmit these to a PLC, which in turn processes the data and passes it to the Fanuc robot controller.

With this data, both of the robots then go head first into the correct positions on the underbody and the wheel arches, which then have the sealant applied to them exactly where it’s needed.

Since the car bodies then go directly to be painted, it is very important that the underbody is sealed in the required areas. Without robot control and with the resulting inaccuracies in the application of the sealant, there would be unsealed areas on the vehicle floor and hence early corrosion damage in the future.

Robot control when stamping the vehicle identification number in the new Golf

To stamp the vehicle identification numbers or VIN numbers on the cars, in Hall 4 of the Mosel plant the stamping units are positioned at three points in the vehicle interior and engine compartment.

The process is as follows: two painted car bodies enter the dual station so that the VIN numbers can be stamped on them. Subsequently, at the two stations, the position data for the relevant car body is determined with the aid of three intelligent vision sensors and this is transmitted to a PLC. This processes the data accordingly and transfers it to the relevant Fanuc robot.

With the positioning data, the robot consecutively approaches the two stamping positions in the vehicle interior, followed by the one in the engine compartment, where it stamps the VIN numbers in exactly the right position. The massive stamping head means that precise positioning of the robot when stamping the VIN is particularly important.

Whether the stamping in question is in the engine compartment, where it is on a very small and precisely defined area, or in the vehicle interior, where the robot has to position the stamping head through the open passenger door very accurately, Omron’s intelligent vision sensor provides the precise position data for the vehicle body, thereby ensuring the correct positioning of the robot.