Precise 3D measurements under operational conditions represent a big challenge for quality assurance in aircraft construction. The measurement technology at the AIRBUS plant in Hamburg has met this challenge by using a mobile photogrammetric measurement system.
AIRBUS utilises the capacities and expertise of 16 locations in France, Spain , Great Britain and Germany . But complete aircraft sections are produced only in Hamburg and St. Nazaire. This unique industrial concept, based on “Centres of Excellence“, has proven to be extremely efficient. “ Hamburg 's share of this project is the manufacture of the front and rear fuselage sections for the AIRBUS models, including the A380.
The A320 models also undergo final assembly here, which means the cockpit is joined to the middle section of the fuselage and the wings,” explains Uwe Drohne, Head of Measurement Technology at AIRBUS in Hamburg.
The 15-member measurement technology team of Uwe Drohne represents one group within quality assurance. Its tasks comprise everything having to do with geometric measurement technology. In order to be able to optimally perform all required measuring tasks, the technicians have at their disposal a number of proven systems. These range from stationary coordinate measuring systems to laser trackers and tachymeters.and includes the V-STARS mobile photogrammetry system.
V-STARS is a mobile coordinate measurement system whose use of a single INCA camera (V-STARS/S) or two or more INCA cameras (V-STARS/M) makes possible quick and highly-precise 3D captures. Digital images taken from various angles are automatically processed by the V-STARS software, and the 3D coordinates of the measured object are calculated. These coordinates can be graphically displayed and analyzed by V-STARS (or other third party software). The stated measuring accuracy of the V-STARS/S system is 5 µm + 5 µm / m using one camera. Where two or more INCA cameras are connected, the measuring accuracy is 10 µm + 10 µm / m.
The Hamburg facility has eight V-STARS systems. Additional systems are in use in other AIRBUS plants.
The first INCA1 system was made available to Uwe Drohne on a lease basis for one year. During that time, he and his team gathered extensive experience with the system, judged it to be good and finally acquired one. “V-STARS made an impression with the accuracy, the expected reliability and manageability of its compact camera. Today, three INCA2 and five INCA3 systems are in use in the measurement technology department,” reports Roland Kinzel, general manager of GDV Systems GmbH
The application the V-STARS systems include the periodic testing of large-scale construction fixtures. These are assembly devices in which parts of aircraft sections are built. Another application is on fuselage section interfaces whereby each fuselage Hamburg delivers to other AIRBUS plants is measured with the V-STARS system. In addition to these two measurements, the mobile measurement system performs many other measurements such as on passenger door frames, cargo hold door frames and supports in the aircraft. The measurement technicians have also used the system to perform measurements on the wings or during testing, as well as deformation measurements, proving that the measurement system has wide application.
“ The photogrammetric V-STARS system is very well suited for measurements in unstable environments such as on a wobbly platform,” explains Andreas Kunkel, responsible for photogrammetry in the measurement technology department. “The same applies to measurements in the aircraft and for measuring a large number of points. A classic example is deformation measurements where 2,000 to 3,000 points have to be measured at once.“
The V-STARS system is also ideally suited for measurements in cases where the technicians in Hamburg have only limited access time – for component and section measurements during their lunch break, for instance. This gives the measuring technicians a window of 30 minutes, but in that timeframe measurement, normally taking 15 to 20 minutes, must be completed. Measurements in tight spatial conditions are also possible, such as in the cargo compartment of small aircraft, where an operator is only able to move in a crouched position and may have to perform measurements tasks behind or around pipes. The comparatively small camera of the V-STARS system allows the technicians flexibility to achieve these tasks.
The technicians in Hamburg use the V-STARS systems several times a day, 700 times a year for fuselage section interface measurements alone. Uwe Drohne comments that not only is the V-Stars photogrammetry system easy to use - “after a short training period, you can hand them to someone and be off and running.”- but that with the analogue system previously employed, the current measurement tasks could not be be managed, either in terms of practicability or speed of data output, let alone with the same number of workers. l
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