IPROMES - Using Image Processing as a Metrological Solution
Overview
Background & policy context:
The importance of metrological controls is increasing in the engineering industry, and particularly in aeronautics, due to the high measurement precision and quality requirements. This important operation varies from an average of 1% to 15% of the aeronautics total production time, depending on the type of produced parts or assembly. This is considerable for a sector where the production time is very high. Unfortunately, in order to reach the high level of quality, performance and safety needs, European aircraft industries have been obliged to invest in expensive and specific solutions as the dimensional precision and the positioning issues are critical.
Objectives:
This project aimed to use photogrammetry and image processing techniques to perform the 'in-process' positioning during the assembly phase and to complete the final measurement control (quality control, maintenance) of aircraft parts afterwards. This project used optical sensors (cameras) instead of the traditional gauges in order to automatically access geometrical data of parts and structures to be controlled, and then to proceed with three-dimensional measurements. With this optical solution, the manufacturing of the frame will be simplified. Thanks to the photogrammetry technique, the measurements will be calculated in real time with instant feedback from the cameras. Implementing a non-contact measurement system will allow drastic reduction of the control duration and standardisation of the control tools.
This project was expected to lead to the following results:
- New image processing algorithms,
- new optical sensors meeting the requirements of the aeronautical sector,
- a 'steps and gaps' optical measurement system for aeronautics, a flexible frame prototype equipped with optical sensors, and
- new assembly concepts.
Methodology:
The innovative solution was based on photogrammetric and image processing techniques. Simultaneously, it offers a high precision, resulting from the use of photogrammetric techniques, and rapidity and ease-of-use, resulting from the use of automatic image processing. With an image processing-based technology, the images can be stored and thus it remains possible, months or years later, to proceed with a complementary measurement of specific characteristics of the part under scrutiny. This is very useful in terms of traceability. Secondly, a simultaneous measurement system can be used to assist the operator in positioning parts during the assembly process.
The measurement system is thus not only useful in control operation but effectively becomes an assembly process tool. Thanks to the optical solution, an innovative framing concept will be set up, so no positioning issue will be required. As the frame will only support the sensors, it will be simplified compared to the current ones. This improvement will lead to proposals for adoption of a 'universal frame'. Indeed, with such a measurement system it becomes possible to create multi-purpose and versatile frames, which can be used for different types of aircraft (for example Airbus A320/A340).
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