Research On Digital Detection Technology For The Shape Of Aircraft Sheet Metal Parts

The rapid development of digital measure technology provides various of measuring means withlarge range, high accuracy and high efficiency, for aircraft sheet metal parts. At present, both domesticand international aircraft manufacturers accomplish aircraft sheet metal parts with digital measuringequipments, such as laser tracker, indoor GPS, laser radar, etc. The digital measuring equipments inthe area of aircraft sheet metal parts in china are applied in primary status, facing the problems thatmeasuring manually without an unified technological process, the quality of the result is mostlydepended on the experience of the technicians. All of these cause many problems, such as lowefficiency and long period. That can’t meet the requirements of modernized aircraft digital andautomatic measurement. Hence, according to the present situation and actual demand of theaeronautical manufacturing enterprise, taking aircraft sheet metal parts contour detection as theresearch object, established the unified spatial metrology network. A unified process and measurementstandards for the measure of aircraft sheet metal parts is provided. The main research in this thesis isoutlined as follow:1) A kind of digital detection method based on laser radar for aircraft sheet metal parts shapedetection is studied, and put forward the rule of laser radar measurement, has realized the automaticpositioning, automatic measurement of target, reduce manual intervention, improve the efficiency ofthe measurement.2) The algorithm for the measurement data reduction and noise processing is studied, processingthe measurement data by the improved fast median filter algorithm and k-nearest neighbor algorithm.By simplifying the measurement data and eliminate noise reducing measurement error.3) Source of measurement error in the detection system is analyzed. The technology of grosserror detection based on the uncertainty of error ellipsoid model is studied. Calculate the error ofmeasurement on the probability of error ellipsoid.4) Based on the above theoretical studies, an aircraft sheet metal parts of digital detection systemis developed which achieved the datum point measurement, automatic measurement, gross errordetection, etc.The application shows that the system can meet the demands and improve the efficiencyof digital measurement.