The usage of chrome or highly polished precision tooling (reference) spheres is common in the calibration and operational characterization of measurement systems such as a Coordinate Measurement Machine (CMM). The usage of a three-dimensional, (3D) laser triangulation, non-contact measurement system on CMMs and other scanning systems pose several obstacles. The highly specular mirror finish on the tooling sphere provides an accurate mechanical entity that has adverse results with laser sensors. The development of tooling spheres with a diffuse surface would benefit laser based measurement systems. The surface roughness and reflectivity properties have an effect on the laser measurements' accuracy. Efforts to develop spheres and establish meaningful measurements of spheres with modified surface finishes are investigated.
Heating and cooling air for an aircraft interior is transported using metal ducts. These ducts vary in size from a few centimeters to 20 centimeters in diameter. In the assembly of aircraft components, a coupling is swaged onto the ducts. In assuring the mechanical dies are operating properly, the crimp mark is checked. The current method of visual inspection and checking with calipers does not allow implementation of statistical process control methods. In an effort to improve this process check, a new measurement method is being developed. A feasibility study indicated that a structured light laser system would be a good approach. A few requirements were: it must be portable to be used at different locations within the fabrication area, it must be fast, it should be easy to use by the mechanic/inspector, the readings must be accurate, and the system is non destructive. Due to the mechanical configuration of the tube and coupling, a camera with magnification optics is used. The measurement of the bump has a maximum of 50.8 microns (0.0020 inch). The system uses computer vision, and custom software written in C++. A low cost frame grabber is used. This paper shows the final production prototype system and its configuration for factory testing. This paper discusses the design and testing of the system.
Heating and cooling air for an aircraft interior is transported using metal ducts. These ducts vary in size from a few centimeters to twelve centimeters in diameter. In the assembly of aircraft air ducts, coupling is swaged onto the ducts. In assuring the mechanical dies are operating properly the die parting welt mark is inspected. The current method of visual inspection and checking with calipers does not allow implementation of statistical process control methods. In an effort to improve this process check, a new measurement method is being developed. A feasibility study indicated that a structured light laser system would be a good approach. A few requirements are: it must be portable to be used at different locations within the fabrication area, it must be fast, it should be easy to use by the mechanic, the reading must be accurate, a hard copy print out is required, and it must be non-destructive. Due to the mechanical configuration of the duct and coupling, a camera with magnification optics is used. The measurement of the bump has a maximum height of 50.8 microns. The prototype systems uses computer vision and custom software written in the C language. This paper discusses different measurement methods tested and the benefits of each technology. The development of a specialized system is justified for production use. This paper describes the prototype system and some of its configuration for factory testing.
In assuring the quality of aircraft, the skin quality must be free of surface imperfections. Surface imperfections such as scratches are unacceptable for cosmetic and structural reasons. Scratches beyond a certain depth are not repairable, resulting in costly replacement of an aircraft's part. Measurements of aircraft exterior surfaces require a ladder or cherry picker for positioning the inspector. Commercially-available computer vision systems are not portable, easy to use, or ergonomic. The machine vision system must be designed with these criteria in mind. The scratch measurement system (SMS) uses computer vision, digital signal processing, and automated inspection methods. The system is portable and battery powered. It is certified for measuring the depth and width of the anomaly. The SMS provides a comprehensive, analytical, and accurate reading. A hardcopy output provides a permanent record of the analysis. The graphical data shows the surface profile and provides substantial information of the surface anomaly. The factory and flight line use the SMS at different stages of aircraft production. Six systems have been built for use within Boeing. A patent was issued for the SMS in February 1994.
Aircraft skins and windows must not have scratches, which are unacceptable for cosmetic and structural reasons. Manual methods are inadequate in giving accurate reading and do not provide a hardcopy report. A prototype scratch measurement system (SMS) using computer vision and image analysis has been developed. This paper discusses the prototype description, novel ideas, improvements, repeatability, reproducibility, accuracy, and the calibration method. Boeing's Calibration Certification Laboratory has given the prototype a qualified certification. The SMS is portable for usage in factory or aircraft hangars anywhere in the world.
In assuring the quality of aircraft skin, it must be free of surface imperfections and structural defects. Manual inspection methods involve mechanical and optical technologies. Machine vision instrumentation can be automated for increasing the inspection rate and repeatability of measurement. As shown by previous industry experience, machine vision instrumentation methods are not calibrated and certified as easily as mechanical devices. The defect must be accurately measured and documented via a printout for engineering evaluation and disposition. In the actual usage of the instrument for inspection, the device must be portable for factory usage, on the flight line, or on an aircraft anywhere in the world. The instrumentation must be inexpensive and operable by a mechanic/technician level of training. The instrument design requirements are extensive, requiring a multidisciplinary approach for the research and development. This paper presents the image analysis results of microscopic structures laser images of scratches on various surfaces. Also discussed are the hardware and algorithms used for the microscopic structures laser images. Dedicated hardware and embedded software for implementing the image acquisition and analysis have been developed. The human interface, human vision is used for determining which image should be processed. Once the image is chosen for analysis, the final answer is a numerical value of the scratch depth. The result is an answer that is reliable and repeatable. The prototype has been built and demonstrated to Boeing Commercial Airplanes Group factory Quality Assurance and flight test management with favorable response.
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