KUKA Roboter GmbH in Augsburg, Germany, is a world leader in the manufacture of industrial robots. In 2007, KUKA produced 9,000 robots with a total staff of 2,000. Apart from customers in the automotive industry, KUKA also supplies the food industry with “wash-down robots” for hygienic areas and “seat test robots” for the furniture and aviation industries. KUKA robots even starred in the James Bond film, Die Another Day, together with Pierce Brosnan and Halle Berry. Individually produced to customer specifications, KUKA robots must achieve maximum precision. Both their position measurement and their validation play a vital part in this.
Recalling the “classic” determination of measured values used until just a few years ago is like traveling back in time. In the past, the robot had to move to four points and, as far as possible, reach a “point-to-point position”. The deviations between the points were assessed visually – a rather subjective measuring method.
When the robot’s positioning has to be very precise, the FARO Laser Tracker is being employed. The high precision portable coordinate measuring machine (CMM) calculates exact positions by means of a laser beam. The robots are set up in particular positions at the measuring stations in order to measure the required positional data. Afterwards, the free parameters are optimized and the measured values are fed back into the control algorithms. In the next step, the robots move to other positions in the quality control check to collect the associated positional data with the Laser Tracker. Thanks to this validation, potential system errors can be totally ruled out.
Dr. Dietmar Tscharnuter, Team Manager of one of the mechanical departments explains, “The robots are manufactured individually and therefore have to be measured individually after completion of the assembly. This is an elaborate procedure. Due to the high precision requirements, it is not just the type-specific defaults that are checked. The control algorithms are modified as well.”