Читать книгу Computer Vision for Structural Dynamics and Health Monitoring - Dongming Feng - Страница 4

1 Chapter 1Figure 1.1 Common displacement sensors: (a) LVDT; (b) laser vibrometer; (c) ...Figure 1.2 Vision‐based remote displacement sensor.

2 Chapter 2Figure 2.1 Commercially available video cameras: (a) CMOS image sensor with ...Figure 2.2 Vision‐based multi‐camera measurement system.Figure 2.3 Time synchronization.Figure 2.4 Procedure for 2D vision sensor implementation.Figure 2.5 Defining a template subset in a source image.Figure 2.6 Surface plot of the NCC and template coordinates in image 1.Figure 2.7 Surface plot of the NCC and template coordinates in image 2.Figure 2.8 Schematic of stereo camera calibration.Figure 2.9 Scaling factor determination: (a) optical axis perpendicular to t...Figure 2.10 Error resulting from camera non‐perpendicularity: (a) effect of ...Figure 2.11 Flowchart of the UCC implementation.Figure 2.12 Orientation code (N = 16).Figure 2.13 Matching results for images in ill conditions: (a) searching for...Figure 2.14 Bilinear interpolation for sub‐pixel analysis.Figure 2.15 Flowchart of vision sensor based on OCM.Figure 2.16 User interface of the OCM‐based displacement measurement softwar...

3 Chapter 3Figure 3.1 Shaking table test.Figure 3.2 Comparison of sinusoidal displacements by the LVDT and vision sen...Figure 3.3 Comparison of earthquake displacements by the LVDT and vision sen...Figure 3.4 Shaking table test of a three‐story frame structure: (a) shaking ...Figure 3.5 Subpixel resolution evaluation using a UCC‐based vision sensor: (...Figure 3.6 Comparison of displacements by OCM (artificial target), UCC (arti...Figure 3.7 Comparison of displacements by OCM (natural target), UCC (natural...Figure 3.8 Evaluation of robustness in unfavorable conditions.Figure 3.9 Case 1 comparison: (a) displacements by OCM and UCC; (b) UCC cros...Figure 3.10 Case 2 comparison: (a) displacements by OCM and UCC; (b) UCC cro...Figure 3.11 Case 3 comparison: (a) displacements by OCM and UCC; (b) UCC cro...Figure 3.12 Case 4 comparison: (a) displacements by OCM and UCC; (b) UCC cro...Figure 3.13 A steel building frame model on a seismic shaking table.Figure 3.14 Seismic shaking table setup.Figure 3.15 Experimental results of the seismic shaking table test: (a) meas...Figure 3.16 Test setup for the simply supported beam.Figure 3.17 Schematic of sensor placement.Figure 3.18 Case of a non‐perpendicular camera optical lens axis.Figure 3.19 Images of a marker panel for different camera tilt angles: (a) 3...Figure 3.20 Comparison of displacement measurement at point 16: (a) camera t...Figure 3.21 Field test: (a) Streicker Bridge; (b) artificial target.Figure 3.22 Randomly running pedestrians: displacement measurement by vision...Figure 3.23 Randomly running pedestrians: acceleration measurement: (a) meas...Figure 3.24 Jumping pedestrians: displacement measurement by vision sensor: ...Figure 3.25 Jumping pedestrians: acceleration measurement: (a) measured acce...Figure 3.26 Field test on a highway bridge.Figure 3.27 Experimental results of field tests on a highway bridge: (a) v =...Figure 3.28 View of the two testbed bridges.Figure 3.29 Field tests on the railway bridge: (a) setup of field tests; (b)...Figure 3.30 Target panel and existing features on the railway bridges: (a) H...Figure 3.31 Test H1: comparison of displacements by three sensors (day).Figure 3.32 Test H2: comparison of displacements by three sensors (day).Figure 3.33 Test H3: comparison of displacements by three sensors (day).Figure 3.34 Test H4: comparison of displacements by three sensors (day).Figure 3.35 Test S1: comparison of displacements by two sensors (night).Figure 3.36 Test S2: comparison of displacements by two sensors (night).Figure 3.37 Test S3: comparison of displacements (night).Figure 3.38 Test S4: comparison of displacements (night).Figure 3.39 Schematic illustration of the displacement peak.Figure 3.40 Errors between peak displacements of test H1–H4 of the HCB bridg...Figure 3.41 Errors between peak displacements of the steel bridge in tests S...Figure 3.42 Field test of the Vincent Thomas Bridge: (a) Vincent Thomas Brid...Figure 3.43 Actual images captured by two cameras: (a) artificial target pan...Figure 3.44 Displacement time histories: (a) measurement in the morning; (b)...Figure 3.45 Power spectral distribution: (a) measurement in the morning; (b)...Figure 3.46 Manhattan Bridge: (a) cross‐section; (b) test setup.Figure 3.47 Tracking target on the bridge: (a) one target; (b) simultaneous ...Figure 3.48 Displacement measurement of one target.Figure 3.49 Simultaneous displacement measurements of three targets.Figure 3.50 Tracking targets on the bridge and the background building.Figure 3.51 The camera motion and the mid‐span vertical displacement of the ...

4 Chapter 4Figure 4.1 Typical modal testing and SHM systems using accelerometers: (a) m...Figure 4.2 Comparison of identified mode shapes of the frame structure.Figure 4.3 Displacement measurements at points 2–31 by the vision sensor.Figure 4.4 Comparison of displacement measurements (a) at point 9; (b) at po...Figure 4.5 Frequency results from (a) displacements at points 2–31 by the vi...Figure 4.6 Comparison of mode shapes between the vision sensor and accelerom...Figure 4.7 Stiffness optimization evolution using measurements taken by the ...Figure 4.8 Test setup: (a) beam; (b) camera; (c) schematics of intact and da...Figure 4.9 Displacement measurements at points 2–31.Figure 4.10 Identified first two mode shapes of the intact and damaged beams...Figure 4.11 Damage indices of the damaged beam: (a) MSC damage index; (b) MM...

5 Chapter 5Figure 5.1 Railway bridge for model updating: (a) side view; (b) plan view; ...Figure 5.2 Freight train configuration.Figure 5.3 Displacement history with train speed 8.05 km/h.Figure 5.4 Schematic representation of the bridge‐track‐vehicle interaction ...Figure 5.5 Measured vs. simulated displacement using the initial FE model.Figure 5.6 Sensitivity analysis procedure.Figure 5.7 Objective functions w.r.t. normalized bridge equivalent stiffness...Figure 5.8 Objective functions w.r.t. normalized bridge damping R_α: (a)...Figure 5.9 Objective functions w.r.t. normalized rail bed stiffness: (a) di...Figure 5.10 Objective functions w.r.t. normalized rail bed damping (a) dis...Figure 5.11 Objective functions w.r.t. normalized train suspension stiffness...Figure 5.12 Objective functions w.r.t. normalized train suspension damping:...Figure 5.13 Two‐step FE model‐updating procedure.Figure 5.14 After Step 1: train speed update.Figure 5.15 After Step 2: equivalent bridge stiffness update.Figure 5.16 Bridge under a moving train.Figure 5.17 Power spectral density (PSD) of measured displacement histories:...Figure 5.18 Computed displacement and acceleration time histories and their ...Figure 5.19 Computed displacement and acceleration time histories and their ...Figure 5.20 Computed displacement and acceleration time histories and their ...Figure 5.21 Mid‐span maximum displacements and accelerations w.r.t. differen...

6 Chapter 6Figure 6.1 Schematics of the output‐only simultaneous identification problem...Figure 6.2 Output‐only time‐domain identification procedure.Figure 6.3 Numerical example.Figure 6.4 Effect of the number of sensors and noise level on the evolution ...Figure 6.5 Identification errors for bridge stiffness.Figure 6.6 Comparison of identified and reference impact forces considering ...Figure 6.7 Comparison of predicted and reference/measured displacement respo...Figure 6.8 Effect of the initial stiffness value on the evolution of bridge ...Figure 6.9 Effect of the damping estimate on the evolution of bridge stiffne...Figure 6.10 Comparison of identified and reference impact forces considering...Figure 6.11 Impact test setup.Figure 6.12 Measurement points.Figure 6.13 Comparison of displacement measurements: (a) displacement at poi...Figure 6.14 Beam stiffness identification from different initial stiffness v...Figure 6.15 Identified and measured hammer impact forces.Figure 6.16 Comparison of the predicted and measured beam displacement: (a) ...

7 Chapter 7Figure 7.1 Outline of vision‐based cable tension measurement.Figure 7.2 Hard Rock Stadium.Figure 7.3 Typical cable assembly.Figure 7.4 Implementation of the computer vision sensor in Hard Rock Stadium...Figure 7.5 Measured vibration and PSD function of TD_A cable at Quad A.Figure 7.6 Measured vibration and PSD function of TD_B cable at Quad B.Figure 7.7 Measured vibration and PSD function of TD_C cable at Quad C.Figure 7.8 Measured vibration and PSD function of TD_D cable at Quad D.Figure 7.9 Measured tension forces vs. reference forces for TD cables: (a) Q...Figure 7.10 Measured vibration and PSD function of SLLB cable at Quad C.Figure 7.11 Measured vibration and PSD function of EZUB cable at Quad C.Figure 7.12 Measured vibration and PSD function of EZF cable at Quad C.Figure 7.13 Measured vibration and PSD function of SLF cable at Quad C.Figure 7.14 Measured tension forces for inclined cables using the vision sen...Figure 7.15 Bronx‐Whitestone Bridge.Figure 7.16 Suspender replacement locations.Figure 7.17 Field suspender replacement: (a) jacking apparatus; (b) new tens...Figure 7.18 Vision sensor setup for measuring suspender tension.Figure 7.19 Measured vibration time histories and PSD amplitudes for suspend...

8 Chapter 8Figure 8.1 Bridge inspection: (a) conventional visual inspection; (b) UAV in...Figure 8.2 Examples of visible damage.

9 Appendix 1Figure A.1 Examples of image types: (a) binary image; (b) grayscale image; (...Figure A.2 The 2D Cartesian coordinates of an M × N grayscale image.Figure A.3 Noise‐removal example.Figure A.4 Edge‐detection example.Figure A.5 Discrete Fourier transform of a grayscale image.