We guide your robot and those of Audi

However, the limitations of these systems are soon reached when difficult surfaces and contours are encountered. New smart laser sensor systems provide completely new possibilities.

The renowned carmaker, Audi AG, currently has its largest plant at Ingolstadt, employing a workforce of about 33,000. With a production capacity of approximately 2,200 cars a day, it produces about 1,400 of the A4 model and about 800 of the A3 model. In addition, it manufactures various body components for other series.  

With their state-of-the-art production facilities, the Audi plant ranks as one of the truly high-tech sites in the car manufacturing industry. At the start of 2004, Omron incorporated a system for 3D robot correction and for adhesive bead monitoring in the cockpit pre-assembly section for the new A3.

Precise determination of the positioning of A3 cockpits using smart laser sensors

This application forms part of the last station at the end of the cockpit pre-assembly line prior to the installation of the cockpit in the vehicle. The cockpit, which is guided in on a hanger of an overhead conveyor system, is fixed in place pneumatically at the station so that it can then be measured with a laser profile sensor. For this purpose, the robot positions the laser profile sensor approx. 200 mm in front of defined points on the black mounting plate of the cockpit and scans specific features at a total of 3 points.

A PLC connected to the sensor system records the measured values and, based on them, determines the position of the mounting plate in the space. The corrections, which are calculated from this, such as linear shifts and rotations around the axes, are communicated to the robot. These values then enable the robot to position the adhesive application nozzle on the mounting plate of the cockpit to an accuracy of approx. ± 0.4 mm.

In-line tolerance compensation without any loss of time and quality

In the past, the mounting plate was not measured. As a result, the bead of adhesive was applied relatively impre cisely on account of the tolerances of the mounting plate and hanger.

In order to ensure that the vehicle was properly sealed, an additional quantity of adhesive was applied as a safeguard. Now, while the robot applies the bead of adhesive, a laser sensor permanently monitors the presence and correct height of the bead. In this way, the quality of the bead of adhesive is monitored in-process, all the measured val ues are recorded and displayed on the station controller and are also available for quality management afterwards.

Savings from the measuring system after a short time in operation

After almost a year in operation, the measuring system described here is proving beneficial to AUDI on a number of different points. The planner in charge, Mr. Fleckenstein, points out first and foremost that the bead of adhesive is being positioned with much greater accuracy, facilitating considerable savings in adhesive. Furthermore, this means that there is no need for perma nent visual inspections of cockpit mounting plates to which adhesive has been applied.

Another positive side effect of this is that, through the measurement of the mounting plates, defective or misaligned hangers on the power trolley system are rejected in good time when certain limits are exceeded.