Real-Time Laser Interference Detection of Mechanical Targets Using a 4R Manipulator

Abstract

In this study, a laser interferometric sensing measurement (ISM) system based on a 4R manipulator system is developed to achieve detection of mechanical targets, which aims to realize the real-time, online detection of workpieces with high precision during processing. The 4R mobile manipulator (MM) system is flexible and can move in the workshop, aiming to preliminarily track the position of the workpiece to be measured and locate it at millimeter level. The reference plane of the ISM system is driven by piezoelectric ceramics with the spatial carrier frequency realized and the interferogram obtained by a charge coupled device (CCD) image sensor. The subsequent processing of the interferogram includes fast Fourier transform (FFT), spectrum filtering, phase demodulation, tilt elimination for wave-surface, etc., so as to further restore the surface shape of the measured surface and obtain the surface quality indexes. A novel cosine banded cylindrical (CBC) filter is used to improve the FFT processing accuracy, and a bidirectional extrapolation and interpolation (BEI) technique is proposed for the preprocessing operation of real-time interferograms before FFT processing. Compared with the results from a ZYGO interferometer, the real-time online detection results show the reliability and practicability of this design. The relative error of peak–valley value reflecting the processing accuracy can reach about 0.63%, with the root-mean-square value reaching about 1.36%. Some possible applications of this work include the surface of mechanical parts in the process of online machining, the end face of shaft-like structures, annular surfaces, etc.

Evolution of Crack Analysis in Structures Using Image Processing Technique: A Review

“…This paper was reviewed by Wall et al to provide a comprehensive assessment of 16 solidification crack testing protocols that have been established for both casting and welding processes, encompassing both self-restrained and externally loaded configurations [16]. Liu et al presented the development of a laser interferometric sensing measurement (ISM) system based on a 4R manipulator system for real-time, online detection of mechanical targets with high precision during processing [17]. Erka et al investigated the use of laser scanners and images to detect and quantify surface damage on structures.…”