Non-Contact, 3-D Measurement for Aircraft Surfaces

A shape capture system for field and industrial capture of surface contours and discontinuous shapes is proposed. The system will provide accuracy of 0.01 inch or better at over 1 million points distributed over a region 100 inches across from three ormore images obtained with a high resolution handheld digital camera. A tripod or bench mounted projector projects a pattern onto the surface from which the point positions can be derived. This can be moved to allow capture of different overlapping areaswhich can be combined into a single surface representation. The working envelope of the system is from less than 50 inches to beyond 200 inches, with accuracy proportional to the distance from the projector to the surface. Immediate feedback to theoperator will ensure that all necessary regions are captured and resolved. Deviations from design specifications in new airframe construction and repair of existing airframes can have a significant effect on aircraft performance. Today's techniques ofboundary layer control, closed-loop aerodynamic stability, and very wide flight envelopes require exact conformance to CAD models if aircraft are to perform as designed. All types of aircraft from supersonic military craft to competition sailplanes cansuffer consequences ranging from slight performance impairment to destructive high-speed flutter if aerodynamic surfaces are incorrectly contoured or finished. The proposed measurement system will provide interactive information to repair and qualitycontrol personnel about the contour and smoothness of aircraft skins. This can be used to check final shape and to guide workers in shaping the surfaces.