Development and Uncertainty Characterization of Rotating 3D Velocimetry using a Single Plenoptic Camera

Rotating 3D velocimetry (R3DV) is a single-camera PIV technique designed to track the evolution of flow over a rotor in the rotating reference frame. A high-speed (stationary) plenoptic camera capable of 3D imaging captures the motion of particles within the volume of interest through a revolving mirror from the central hub of a hydrodynamic rotor facility, a by-product being an undesired image rotation. R3DV employs a calibration method adapted for rotation such that during MART reconstruction, voxels are mapped to pixel coordinates based on the mirror’s instantaneous azimuthal position. Interpolation of calibration polynomial coefficients using a fitted Fourier series is performed to bypass the need to physically calibrate volumes corresponding to each fine azimuth angle. Reprojection error associated with calibration is calculated on average to be less than 0.6 of a pixel. Experimental uncertainty of cross-correlated 3D/3C vector fields is quantified by comparing vectors obtained from imaging quiescent flow via a rotating mirror to an idealized model based purely on rotational kinematics. The uncertainty shows no dependency on azimuth angle while amounting to approximately less than 0.21 voxels per timestep in the in-plane directions and correspondingly 1.7 voxels in the radial direction, both comparable to previously established uncertainty estimations for single-camera plenoptic PIV.

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Image-Based Versus Signal-Based Sensors for Machine Fault Detection and Isolation

Volume 3: Engineering Systems; Heat Transfer and Thermal Engineering; Materials and Tribology; Mechatronics; Robotics ◽

10.1115/esda2014-20102 ◽

2014 ◽

Author(s):

Heshan Fernando ◽

Vedang Chauhan ◽

Brian Surgenor

Keyword(s):

Fault Detection ◽

High Speed ◽

Fault Isolation ◽

Video Data ◽

Fault Detection And Isolation ◽

Single Camera ◽

Multiple Faults ◽

Multiple Sensors ◽

Machine Fault ◽

And Performance

This paper presents the results of a comparative study that investigated the use of image-based and signal-based sensors for fault detection and fault isolation of visually-cued faults on an automated assembly machine. The machine assembles 8 mm circular parts, from a bulk-supply, onto continuously moving carriers at a rate of over 100 assemblies per minute. Common faults on the machine include part jams and ejected parts that occur at different locations on the machine. Two sensor systems are installed on the machine for detecting and isolating these faults: an image-based system consisting of a single camera and a signal-based sensor system consisting of multiple greyscale sensors and limit switches. The requirements and performance of both systems are compared for detecting six faults on the assembly machine. It is found that both methods are able to effectively detect the faults but they differ greatly in terms of cost, ease of implementation, detection time and fault isolation capability. The conventional signal-based sensors are low in cost, simple to implement and require little computing power, but the installation is intrusive to the machine and readings from multiple sensors are required for faster fault detection and isolation. The more sophisticated image-based system requires an expensive, high-resolution, high-speed camera and significantly more processing power to detect the same faults; however, the system is not intrusive to the machine, fault isolation becomes a simpler problem with video data, and the single camera is able to detect multiple faults in its field of view.

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Research on Calibration Method of Tire Dynamic Balance Detection System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.542-543.828 ◽

2012 ◽

Vol 542-543 ◽

pp. 828-832 ◽

Cited By ~ 1

Author(s):

Jing Fang Yang ◽

Xian Ying Feng ◽

Hong Jun Fu ◽

Lian Fang Zhao

Keyword(s):

High Speed ◽

Detection System ◽

Dynamic Balance ◽

Calibration Method ◽

Engineering Practice ◽

Influence Coefficient ◽

Quality Factors ◽

High Speed Rotation ◽

Speed Rotation ◽

Upper Rim

Tire dynamic balance detection plays an important part in tire quality detection area. This paper uses the two-sided balance method to obtain the unbalance of the tire. According to the engineering practice, builds kinetic model and then introduces the calculating principle and operating procedures. In order to accurately determine the influence coefficient, a calibration method without tire is put forward. Further more, this new method is able to eliminate the unbalance caused by non-quality factors to some extent. But this method is presented based on the relative position invariance of the upper rim and lower rim, even both of them are under high-speed rotation situation. Finally, the experimental data acquired from both of the two methods are compared. The calibration method without tire is proved to be more feasible, efficient and accurate.

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Design of an Intelligent Multi-Gyro Measurement Device

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.295-296.589 ◽

2005 ◽

Vol 295-296 ◽

pp. 589-594

Author(s):

J.P. Wang ◽

W. Zhou ◽

W.F. Tian ◽

Z.H. Jin

Keyword(s):

High Speed ◽

Dynamic Balance ◽

Control Unit ◽

Calibration Method ◽

Test System ◽

Measurement Device ◽

Logic Control ◽

Hardware Description ◽

Thermal Resistors ◽

Inertial Unit

This paper describes the design of an intelligent multi-gyro measurement device to measure and monitor an inertial unit composed of three dynamically tuned gyros (DTGs). A 16-bit microprogrammed control unit is programmed to fulfill the functions of signal processing, logic control and serial communication with a master computer. An FPGA, designed by using Verilog Hardware Description Language, is used to realize high speed 16-bit reversible counters for output pulses of the DTG digital dynamic balance circuits. The count values represent the angular motion of the inertial unit. A stepping electric bridge is employed to measure the resistance of thermal resistors within the gyros in a wide temperature environment. The resistance represents the working temperature of the gyros. An effective calibration method for the bridge is developed to eliminate the resistance measurement error. A test system is established to examine whether the device meets the user requirements. Results of the tests show that the device has a good performance. A trial use has proved that the device is stable and reliable and that it satisfies the demand of the user.

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LMS Based Ultra-Fast Non Linearity Test and Calibration Method for High-speed and High-Resolution ADC

10.1109/asid52932.2021.9651698 ◽

2021 ◽

Author(s):

Ting Li ◽

Yabo Ni ◽

Yong Zhang ◽

Chao Chen

Keyword(s):

High Resolution ◽

High Speed ◽

Calibration Method ◽

Linearity Test

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Calibration of pneumotachographs using a calibrated syringe

Journal of Applied Physiology ◽

10.1152/japplphysiol.00196.2003 ◽

2003 ◽

Vol 95 (2) ◽

pp. 571-576 ◽

Cited By ~ 14

Author(s):

Yongquan Tang ◽

Martin J. Turner ◽

Johnny S. Yem ◽

A. Barry Baker

Keyword(s):

Calibration Method ◽

Linear Range ◽

Data Sets ◽

Constant Flow ◽

Calibration Constant ◽

Third Order ◽

Polynomial Coefficients ◽

Calibration Curves ◽

Order Polynomial ◽

Better Than

Pneumotachograph require frequent calibration. Constant-flow methods allow polynomial calibration curves to be derived but are time consuming. The iterative syringe stroke technique is moderately efficient but results in discontinuous conductance arrays. This study investigated the derivation of first-, second-, and third-order polynomial calibration curves from 6 to 50 strokes of a calibration syringe. We used multiple linear regression to derive first-, second-, and third-order polynomial coefficients from two sets of 6–50 syringe strokes. In part A, peak flows did not exceed the specified linear range of the pneumotachograph, whereas flows in part B peaked at 160% of the maximum linear range. Conductance arrays were derived from the same data sets by using a published algorithm. Volume errors of the calibration strokes and of separate sets of 70 validation strokes ( part A) and 140 validation strokes ( part B) were calculated by using the polynomials and conductance arrays. Second- and third-order polynomials derived from 10 calibration strokes achieved volume variability equal to or better than conductance arrays derived from 50 strokes. We found that evaluation of conductance arrays using the calibration syringe strokes yields falsely low volume variances. We conclude that accurate polynomial curves can be derived from as few as 10 syringe strokes, and the new polynomial calibration method is substantially more time efficient than previously published conductance methods.

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Crack Propagation Velocity Determination by High-speed Camera Image Sequence Processing

10.20944/preprints202009.0583.v1 ◽

2020 ◽

Author(s):

Frank Liebold ◽

Ali A. Heravi ◽

Oliver Mosig ◽

Manfred Curbach ◽

Viktor Mechtcherine ◽

...

Keyword(s):

Crack Propagation ◽

High Speed ◽

Vector Fields ◽

Displacement Vector ◽

Image Sequence ◽

High Speed Camera ◽

Sequence Processing ◽

Image Sequence Processing ◽

Propagation Velocities

The determination of crack propagation velocities can provide valuable information for a better understanding of damage processes of concrete. The spatio-temporal analysis of crack patterns developing at a speed of several hundred meters per second is a rather challenging task. In the paper, a photogrammetric procedure for the determination of crack propagation velocities in concrete specimens using high-speed camera image sequences is presented. A cascaded image sequence processing which starts with the computation of displacement vector fields for a dense pattern of points on the specimen’s surface between consecutive time steps of the image sequence chain has been developed. These surface points are triangulated into a mesh, and as representations of cracks, discontinuities in the displacement vector fields are found by a deformation analysis applied to all triangles of the mesh. Connected components of the deformed triangles are computed using region-growing techniques. Then, the crack tips are determined using principal component analysis. The tips are tracked in the image sequence and the velocities between the time stamps of the images are derived. A major advantage of this method as compared to established techniques is in the fact of its allowing for spatio-temporally resolved, full-field measurements rather than point-wise measurements and that information on crack width can be obtained simultaneously. To validate the experimentation, the authors processed image sequences of tests on four compact-tension specimens performed on a split-Hopkinson tension bar. The images were taken by a high-speed camera at a frame rate of 160,000 images per second. By applying to these datasets the image sequence processing procedure as developed, crack propagation velocities of about 800 m/s were determined with a precision in the order of 50 m/s.

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Development of a modular, high-speed plenoptic-camera for 3D flow-measurement

Optics Express ◽

10.1364/oe.27.013400 ◽

2019 ◽

Vol 27 (9) ◽

pp. 13400 ◽

Cited By ~ 4

Author(s):

Zu Puayen Tan ◽

Kyle Johnson ◽

Chris Clifford ◽

Brian S. Thurow

Keyword(s):

Flow Measurement ◽

High Speed ◽

3D Flow ◽

Plenoptic Camera

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Charuco Board-Based Omnidirectional Camera Calibration Method

Electronics ◽

10.3390/electronics7120421 ◽

2018 ◽

Vol 7 (12) ◽

pp. 421 ◽

Cited By ~ 11

Author(s):

Gwon An ◽

Siyeong Lee ◽

Min-Woo Seo ◽

Kugjin Yun ◽

Won-Sik Cheong ◽

...

Keyword(s):

Camera Calibration ◽

Mean Absolute Error ◽

Three Dimensional ◽

Absolute Error ◽

Calibration Method ◽

Feature Points ◽

Omnidirectional Camera ◽

Reprojection Error ◽

Conventional Methods ◽

Better Than

In this paper, we propose a Charuco board-based omnidirectional camera calibration method to solve the problem of conventional methods requiring overly complicated calibration procedures. Specifically, the proposed method can easily and precisely provide two-dimensional and three-dimensional coordinates of patterned feature points by arranging the omnidirectional camera in the Charuco board-based cube structure. Then, using the coordinate information of the feature points, an intrinsic calibration of each camera constituting the omnidirectional camera can be performed by estimating the perspective projection matrix. Furthermore, without an additional calibration structure, an extrinsic calibration of each camera can be performed, even though only part of the calibration structure is included in the captured image. Compared to conventional methods, the proposed method exhibits increased reliability, because it does not require additional adjustments to the mirror angle or the positions of several pattern boards. Moreover, the proposed method calibrates independently, regardless of the number of cameras comprising the omnidirectional camera or the camera rig structure. In the experimental results, for the intrinsic parameters, the proposed method yielded an average reprojection error of 0.37 pixels, which was better than that of conventional methods. For the extrinsic parameters, the proposed method had a mean absolute error of 0.90° for rotation displacement and a mean absolute error of 1.32 mm for translation displacement.

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