scholarly journals Accurate 3D Shape, Displacement and Deformation Measurement Using a Smartphone

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 719 ◽  
Author(s):  
Liping Yu ◽  
Ran Tao ◽  
Gilles Lubineau

The stereo-digital image correlation technique using two synchronized industrial-grade cameras has been extensively used for full-field 3D shape, displacement and deformation measurements. However, its use in resource-limited institutions and field settings is inhibited by the need for relatively expensive, bulky and complicated experimental set-ups. To mitigate this problem, we established a cost-effective and ultra-portable smartphone-based stereo-digital image correlation system, which only uses a smartphone and an optical attachment. This optical attachment is composed of four planar mirrors and a 3D-printed mirror support, and can split the incoming scene into two sub-images, simulating a stereovision system using two virtual smartphones. Although such a mirror-based system has already been used for stereo-image correlation, this is the first time it has been combined with a commercial smartphone. This publication explores the potential and limitations of such a configuration. We first verified the effectiveness and accuracy of this system in 3D shape and displacement measurement through shape measurement and in-plane and out-of-plane translation tests. Severe thermal-induced virtual strains (up to 15,000 με) were found in the measured results due to the smartphone heating. The mechanism for the generation of the temperature-dependent errors in this system was clearly and reasonably explained. After a simple preheating process, the smartphone-based system was demonstrated to be accurate in measuring the strain on the surface of a loaded composite specimen, with comparable accuracy to a strain gauge. Measurements of 3D deformation are illustrated by tracking the deformation on the surface of a deflating ball. This cost-effective and ultra-portable smartphone-based system not only greatly decreases the hardware investment in the system construction, but also increases convenience and efficiency of 3D deformation measurements, thus demonstrating a large potential in resource-limited and field settings.

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4726 ◽  
Author(s):  
Bo Dong ◽  
Fancang Zeng ◽  
Bing Pan

A simple and practical full-frame single-camera stereo-digital image correlation (stereo-DIC) technique for three-dimensional (3D) shape, displacement, and deformation measurements is proposed. The technique uses a compact X-cube prism-based color separation device and a color camera to capture images of blue and red colors from different optical paths, and then extracts the surface 3D shape and deformation information of a test sample by processing the captured two sub-channel color images using regular stereo-DIC algorithm. Compared with the existing full-frame single-camera stereo-DICs, the proposed one eliminates the need for a beam splitter and two bandpass filters to capture images, and offers more simple, compact, and easy-to-use optical arrangement. This novel single-camera stereo-DIC technique was validated by a series of baseline experiments involving 3D surface reconstructions, translation tests, and full-field deformation measurements, which provide a new flexible and practical avenue for measuring surface 3D shape and deformation, particularly in microscopic and high-speed applications.


2011 ◽  
Vol 71-78 ◽  
pp. 3904-3908
Author(s):  
Ming Hsiang Shih ◽  
Wen Pei Sung ◽  
Feng Jen Tsai

Strong typhoon and earthquake seriously threaten the safety of the life and property of the people. A cost-effective and reliable method is proposed to monitor the natural frequency response of building under excitation of external forces based on the applying digital image correlation method, DIC. The analysis accuracy of this dynamic DIC method is tested and verified by comparing with numerical analysis program, accelerometers, ACC and fast Fourier Transform, FFT. The test results reveal that the analysis accuracy of this DIC method near to the ACC and FFT traditional experimental methods. They demonstrate that using this DIC method to detect dynamic response of building under the excitation of external force has high practicability.


2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Cong Sun ◽  
Haibo Liu ◽  
Yang Shang ◽  
Shengyi Chen ◽  
Qifeng Yu

To further extend the scope of stereo-digital image correlation (stereo-DIC) to more challenging environments, a novel Scheimpflug camera-based stereo-DIC is developed for full-field 3D deformation measurement, wherein the Scheimpflug condition, consisting of tilting the sensor plane with respect to the lens plane for the sake of larger depth of field (DOF) of the camera, is employed. The geometric imaging model of the Scheimpflug camera is described, on the basis of which a robust and effective stepwise calibration strategy is performed to calculate the intrinsic and extrinsic parameters of the stereo Scheimpflug rig. With the aid of a specially tailored stereo triangulation method and well-developed subset-based DIC algorithms, the three-dimensional shape and displacement of the specimen can be retrieved. Finally, practical experiments, including rigid motion tests and three-point bending tests, demonstrate the effectiveness and accuracy of the proposed approach.


2011 ◽  
Vol 71-78 ◽  
pp. 3899-3903
Author(s):  
Wen Pei Sung ◽  
Ming Hsiang Shih ◽  
Feng Jen Tsai

Recently, some serious earthquakes happened in the world and seriously threaten the safety of the life and property of the people. Monitoring and measuring the quakeproof capacity of building need to install high cost sensitive instruments to provide sufficient information. A cost-effective and reliable method based on the applying digital image correlation method, DIC to monitor the natural frequency of building under excitation of earthquake as damage index is proposed in this research. Using DIC to monitor the structural damage based on the natural frequency as damage index can easily detect the structural damage after the excitation of earthquake. Test results reveal that sensitivity of this DIC method is superior to traditional data collected by installed accelerometers, ACC in structure.


2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Ruili Xie ◽  
Liping Yu ◽  
Weidong Zhu ◽  
Bing Pan

Abstract The flow-induced vibration of a flexible splitter plate behind a circular cylinder is investigated experimentally in this study. Unlike previous studies that mainly devoted to flow dynamics, the full-field three-dimensional (3D) dynamic deformation of a splitter plate behind a cylinder in the wind tunnel is measured with an easy-to-implement, compact but practical single-camera high-speed (SCHS) stereo-digital image correlation (DIC) system. The system parameters of the wind tunnel, the configuration of the SCHS-DIC system, and the measurement principles are introduced first. Then, the effectiveness, accuracy, and stability of the SCHS stereo-DIC system are verified by the deformation measurements of the high-stiffness fixed cylinder. Finally, the full-field dynamic 3D deformation measurements of different splitter plates are carried out under different wind speeds. Results of the polyvinyl chloride (PVC) splitter plate show that the out-of-plane deformation is much larger than in-plane deformation. The maximum deformation occurs at the tip region of the plate, the position of which can move non-periodically along the free-end edge. The full-field deformation of the plate presents the characteristics of complex vortex distribution with high and low fluctuations, and exhibits an asymmetric and non-periodic oscillation in the out-of-plane direction. The comparison results reveal how the wind load and material type of the plate affect the oscillation characteristics.


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