Development of a Point Tracking System for Measuring Structural Deformations Using Commercial Video Cameras

Abstract

This paper deals with the creation of a new, low-cost point/position tracking system that can measure deformations in engineering structures with simple commercially widespread cameras. Though point tracking systems do exist today, such as Stereo Pattern Recognition (SPR) and Projection Moiré Interferometry (PMI) systems, they are far too costly to use to analyze small, simple structures because complex optical components such as large flashes, high-resolution cameras and data acquisition systems with several computers are required. We developed a point tracking system using commercial cameras. This system used IR LEDs and commercial IR CCD cameras to minimize the interference posed by other extraneous light sources. The main algorithm used for this system is an optical point tracking algorithm, which is composed of the point extraction algorithm and the point matching algorithm for 3-D motion estimation. a series of verification tests were performed. Then, the developed point tracking system was applied to measure deformations of an acrylic plate under a mechanical load. The measured deformations of the acrylic plate matched well with the numerical analysis results. The results indicate that the developed point tracking system is reliable enough to measure continuous deformed shapes of various engineering structures.

Performance evaluation method of homogeneous stereo camera system for full-field structural deformation estimation

“…In addition, it is superior to other non-contact methods, such as those using laser displacement sensors (LDS), because it is capable of a fullfield measurement with the use of only a single set of sensors. Owing to these advantages, its application ranges from the deflection estimation of laboratory test structure model [3,4] to various maneuvering structures such as aircraft wings [5][6][7], rotor blades [8][9][10] and civil infrastructures [11][12][13][14].…”