Stationary circular target patterns in a surface burning reaction

1996 ◽  
Vol 30 (4) ◽  
pp. 471-486 ◽  
Author(s):  
Larry K. Forbes
Keyword(s):  
Surface Burning ◽  
Circular Target

Structural displacement and strain monitoring based on the edge detection operator

2016 ◽  
Vol 20 (2) ◽  
pp. 191-201 ◽  
Author(s):  
Wei Lu ◽  
Yan Cui ◽  
Jun Teng
Keyword(s):  
Edge Detection ◽  
Image Features ◽  
Image Feature ◽  
Monitoring Method ◽  
Strain Monitoring ◽  
Morphological Operator ◽  
Filtering Effect ◽  
Circular Target ◽  
Plane Displacement ◽  
The Cost

To decrease the cost of instrumentation for the strain and displacement monitoring method that uses sensors as well as considers the structural health monitoring challenges in sensor installation, it is necessary to develop a machine vision-based monitoring method. For this method, the most important step is the accurate extraction of the image feature. In this article, the edge detection operator based on multi-scale structure elements and the compound mathematical morphological operator is proposed to provide improved image feature extraction. The proposed method can not only achieve an improved filtering effect and anti-noise ability but can also detect the edge more accurately. Furthermore, the required image features (vertex of a square calibration board and centroid of a circular target) can be accurately extracted using the extracted image edge information. For validation, the monitoring tests for the structural local mean strain and in-plane displacement were designed accordingly. Through analysis of the error between the measured and calculated values of the structural strain and displacement, the feasibility and effectiveness of the proposed edge detection operator are verified.

Influence of the behavioral goal and environmental obstacles on rapid feedback responses

2012 ◽  
Vol 108 (4) ◽  
pp. 999-1009 ◽  
Author(s):  
Joseph Y. Nashed ◽  
Frédéric Crevecoeur ◽  
Stephen H. Scott
Keyword(s):  
Muscle Activity ◽  
Motor System ◽  
Optimal Feedback Control ◽  
Motor Responses ◽  
Spatial Properties ◽  
Long Latency ◽  
Circular Target ◽  
Motor Actions ◽  
Behavioral Goal ◽  
Feedback Responses

The motor system must consider a variety of environmental factors when executing voluntary motor actions, such as the shape of the goal or the possible presence of intervening obstacles. It remains unknown whether rapid feedback responses to mechanical perturbations also consider these factors. Our first experiment quantified how feedback corrections were altered by target shape, which was either a circular dot or a bar. Unperturbed movements to each target were qualitatively similar on average but with greater dispersion of end point positions when reaching to the bar. On random trials, multijoint torque perturbations deviated the hand left or right. When reaching to a circular target, perturbations elicited corrective movements that were directed straight to the location of the target. In contrast, corrective movements when reaching to a bar were redirected to other locations along the bar axis. Our second experiment quantified whether the presence of obstacles could interfere with feedback corrections. We found that hand trajectories after the perturbations were altered to avoid obstacles in the environment. Importantly, changes in muscle activity reflecting the different target shapes (bar vs. dot) or the presence of obstacles were observed in as little as 70 ms. Such changes in motor responses were qualitatively consistent with simulations based on optimal feedback control. Taken together, these results highlight that long-latency motor responses consider spatial properties of the goal and environment.

scholarly journals Postural Constraints on Movement Variability

2010 ◽  
Vol 104 (2) ◽  
pp. 1061-1067 ◽  
Author(s):  
Daniel R. Lametti ◽  
David J. Ostry
Keyword(s):  
Visual Display ◽  
Movement Direction ◽  
Control Mechanisms ◽  
Robotic Device ◽  
Movement Variability ◽  
Base Level ◽  
Limb Stiffness ◽  
Actual Movement ◽  
Visual Motor ◽  
Circular Target

Movements are inherently variable. When we move to a particular point in space, a cloud of final limb positions is observed around the target. Previously we noted that patterns of variability at the end of movement to a circular target were not circular, but instead reflected patterns of limb stiffness—in directions where limb stiffness was high, variability in end position was low, and vice versa. Here we examine the determinants of variability at movement end in more detail. To do this, we have subjects move the handle of a robotic device from different starting positions into a circular target. We use position servocontrolled displacements of the robot's handle to measure limb stiffness at the end of movement and we also record patterns of end position variability. To examine the effect of change in posture on movement variability, we use a visual motor transformation in which we change the limb configuration and also the actual movement target, while holding constant the visual display. We find that, regardless of movement direction, patterns of variability at the end of movement vary systematically with limb configuration and are also related to patterns of limb stiffness, which are likewise configuration dependent. The result suggests that postural configuration determines the base level of movement variability, on top of which control mechanisms can act to further alter variability.

Processing Robot and Sensor Log Files: Seeking a Circular Target

2015 ◽  
pp. 171-215
Author(s):  
Samuel Buttrey ◽  
Timothy Chung ◽  
James Eagle ◽  
Duncan Lang
Keyword(s):  
Log Files ◽  
Circular Target

scholarly journals Calibration Method for Line-Structured Light Three-Dimensional Measurements Based on a Single Circular Target

2022 ◽  
Vol 12 (2) ◽  
pp. 588
Author(s):  
Jun Wang ◽  
Xuexing Li
Keyword(s):  
Structured Light ◽  
Three Dimensional ◽  
Calibration Method ◽  
Optical Center ◽  
3D Measurements ◽  
Light Plane ◽  
Laser Projector ◽  
Dimensional Measurements ◽  
Intersection Points ◽  
Circular Target

Single circular targets are widely used as calibration objects during line-structured light three-dimensional (3D) measurements because they are versatile and easy to manufacture. This paper proposes a new calibration method for line-structured light 3D measurements based on a single circular target. First, the target is placed in several positions and illuminated by a light beam emitted from a laser projector. A camera captures the resulting images and extracts an elliptic fitting profile of the target and the laser stripe. Second, an elliptical cone equation defined by the elliptic fitting profile and optical center of the camera is established based on the projective geometry. By combining the obtained elliptical cone and the known diameter of the circular target, two possible positions and orientations of the circular target are determined and two groups of 3D intersection points between the light plane and the circular target are identified. Finally, the correct group of 3D intersection points is filtered and the light plane is progressively fitted. The accuracy and effectiveness of the proposed method are verified both theoretically and experimentally. The obtained results indicate that a calibration accuracy of 0.05 mm can be achieved for an 80 mm × 80 mm planar target.

Precision circular target location in vision coordinate measurement system

2007 ◽  
Author(s):  
Liwen Wang ◽  
Lei Zhang ◽  
Zhijing Yu ◽  
Fei Chen ◽  
Xiayan Si ◽  
...  
Keyword(s):  
Measurement System ◽  
Target Location ◽  
Coordinate Measurement ◽  
Circular Target

Feasibility Study for Vision-Based Cable Force Measurement Using Smartphone

2016 ◽  
Author(s):  
Xuefeng Zhao ◽  
Kwang Ri ◽  
Yan Yu ◽  
Chunil Kang ◽  
Mingchu Li ◽  
...  
Keyword(s):  
Measurement Method ◽  
Force Measurement ◽  
Smartphone Application ◽  
Cable Model ◽  
Construction Period ◽  
Service Period ◽  
Cable Force ◽  
Vibration Responses ◽  
Cable Force Measurement ◽  
Circular Target

An accurate cable force measurement is one of very important practical problems during construction period as well as during service period of cable stayed bridge. In the recent years, with the advances in smartphone technologies, it is possible to rapidly evaluate structural health status and postevent damage using ubiquitous smartphones. In this paper, a novel vision-based cable force measurement method using smartphone camera is proposed for the first time, which enable to estimate cable force by recognizing cable vibration using smartphone camera, and then cable model test is carried out to verify the feasibility of the proposed method. The comparison test between the smartphone application Orion-CC measuring cable force from smartphone built-in accelerometer and the proposed method is conducted on a laboratory scale cable model with different sampling rates. In the proposed method, the vibration responses of cable are obtained by monitoring displacements of a preprinted black circular target attached on the cable model using smartphone camera. The test results showed satisfactory agreements between two methods in both frequency domain and cable force value, demonstrating the feasibility of the proposed cable force measurement method and its advantages such as convenience, ease of operation, and speediness.

Fly ash/ripoxy composite: Inflammability on horizontal and surface burning

2020 ◽  
Author(s):  
K. Diharjo ◽  
Y. Prasetya ◽  
M. Masykuri ◽  
N. S. Suharty
Keyword(s):  
Fly Ash ◽  
Surface Burning

scholarly journals Field Geometric Calibration Method for Line Structured Light Sensor Using Single Circular Target

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Tianfei Chen ◽  
Lijun Sun ◽  
Qiuwen Zhang ◽  
Xiang Wu ◽  
Defeng Wu
Keyword(s):  
Structured Light ◽  
Linear Equations ◽  
Calibration Method ◽  
Experimental Result ◽  
Normal Vector ◽  
Geometric Calibration ◽  
Light Plane ◽  
Light Sensor ◽  
Fitting Method ◽  
Circular Target

To achieve fast calibration of line structured light sensor, a geometric calibration approach based on single circular calibration target is proposed. The proposed method uses the circular points to establish linear equations, and according to the angle constraint, the camera intrinsic parameters can be calculated through optimization. Then, the light plane calibration is accomplished in two steps. Firstly, when the vanishing lines of target plane at various postures are obtained, the intersections between vanishing lines and laser stripe can be computed, and the normal vector of light plane can be calibrated via line fitting method using intersection points. After that, the distance from the origin of camera coordinate system to the light plane can be derived based on the model of perspective-three-point. The actual experimental result shows that this calibration method has high accuracy, its average measuring accuracy is 0.0451 mm, and relative error is 0.2314%. In addition, the entire calibration process has no complex operations. It is simple, convenient, and suitable for calibration on sites.

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