A Quick Vision Inspection Technique For The Large Number Of Small Guide Holes On Complex Aircraft Parts

As one of the most common feature types in aircraft structures, guide holes exist in many kinds of aircraft parts such as frames, ribs, sidings, and skins etc.. Guide hole machining quality is critical to the life of the aircraft and flight safety. When quality defects like geometrical bias appear in guide holes, the assembly stress will be generated, and will threaten the safety of aircraft.New generation of aircrafts require higher machining quality of the guide holes. Unfortunately, the traditional methods of guide hole inspection cannot meet the requirements in accuracy and efficiency. In order to realize fast, on spot and quantitative inspection of the large number of small guide holes on complex aircraft parts, a quick vision inspection system MBMS is designed and implemented in this thesis. The main contributions are as follows. 1. A new method to inspect guide hole is proposed, which combines a visual sensor with a multi-axis CNC equipment. This method possesses the advantages of high precision, high efficiency and non-contact. The limitation of inspection range of simple visual detection methods is overcame. The proposed method meets the new inspection requirements in guide hole manufacturing. A method to calibrate the system's internal and external parameters is proposed. The system's internal and external parameters are calibrated through one calibration procedure,which is simple, precise, and suits for engineering applications. 2. The programming method to generate NC inspection program is discussed in detail, and the guide holes' inspection order is optimally planned based on the traveling salesman algorithm. 3. The image processing method of guide holes is studied deeply. An accurate and stable method is proposed to locate the guide hole in the image, which is using the obvious edges in the binary image to choose the edge in canny image of the guide hole, and then get final result by iterative fitting upon the chosen edges. 4. The evaluation method of guide hole's machining precision in vision inspection is studied, which is achieved by comparing the real image with the underlying virtual image.On the foundation of key research achievements, the system's hardware platform is designed and made based on Mik RON UCP710, and the system's software is developed on the VS2010 platform. The proposed system functionalities have been experimented and analyzed though conducting an experiment on test part.