Remote Inspection Technologies for Aircraft Skin Inspection

Abstract

Aircraft flight pressurization/depressurization cycles cause their skins to inflate and deflate, stressing the skin around the rivets that fasten it to the airframe. The resulting strain, exacerbated by any corrosion that might be present, drives the growth of the initially microscopic cracks that are an unavoidable by-product of rivet installation. To avoid catastrophe, aircraft are periodically inspected for cracks and corrosion. The inspection technology employed is ~90% naked-eye vision. Of the ~10% that is instrumented, ~90% is with hand-held eddy current pencil probes. We have developed and demonstrated robotic deployment of remote eddy current and remote enhanced stereoscopic video instrumentation, augmented by image enhancement and image understanding algorithms, aimed at alleviating human performance problems and workplace hazards in inspection. This paper describes the aircraft skin inspection application, our two robotic deployment systems, the corresponding instrumentation packages we have demonstrated, and our progress toward developing image enhancement and understanding techniques to assist aircraft inspectors in finding cracks and corrosion. A wavelet-based approach is able to select radial features around rivets, and then to discriminate between cracks and scratches.