Research On Key Technology Of Digital Inspection System Of The Parts Of Airplane

In aircraft manufacturing, techniques of processing and detecting complex surfaces have become a symbol of scientific and technological level of a country. Although CNC machining technology of aircraft parts and dies which contain free-form surfaces have made remarkable progress, automation degree of detection and quality assurance of above them has always been very low. In this paper, digital detection technology of aircraft parts and components is discussed, detection scheme which integrate the line structured light sensor and machine vision under CMM control is put forward, and key technologies of above technique are researched in depth.Main works of us focus on following parts:1.According to structure feature and detecting requirement of the aircraft parts and components, a multiple sensor detection model is set up, which distributes detection tasks among CMM contact measurement, line structured light visual detection system and binocular vision measurement system in order to get complete part appearance data. Quality evaluation method and indicator of complicated shape is also established, which can be used as guidelines to compare measuring data with digital produce model, thus quality detection of typical aircraft components and parts can be realize.2. Connection between devices such as CCD camera, IEEE1394 card, line-structure laser senor, power supply with computer system is established, interface programs used to getting image is coded, which can set parameters, customize model of shoot and frame-ratio, and save the image files.3. Image process algorithms are studied, which include eliminating random noise of image data, devising laser-stripes image and getting center points from these stripes. An advanced median-filter arithmetic based on 5×5 windows is used to eliminate random noise, thus simplify latter image process, reduces misjudgments in the process of getting center points and increasing the reliability of measurement data. 4. Mathematical model of CCD camera based on pin-hole imaging theory set up by us has considered the influence of radial distortion error towards measurement data, based on above theory a calibration method which have two main steps is provided. Only one shoot to calibration model is needed to get all the inner and outer parameters of the camera. Equation of projection plane is acquired by three non-linear points, combined with above results the calibration of line structured light senor can be deduced.5. An experimental inspection system is developed with VC++6.0. Through this system, 3D digital information of measuring data is derived from image information, and then precision of this system is verified by these data.