One- and two-dimensional, differential, reflective fiber displacement sensors

1985 ◽  
Vol 24 (15) ◽  
pp. 2369 ◽  
Author(s):  
Mark Johnson ◽  
Gabriel Goodman
Keyword(s):  
Two Dimensional ◽  
Displacement Sensors

Vision-Based Sensing in Dynamic Tests

2013 ◽  
Vol 569-570 ◽  
pp. 767-774 ◽  
Author(s):  
Fabio Casciati ◽  
Sara Casciati ◽  
Li Jun Wu
Keyword(s):  
Real World ◽  
Affine Transformation ◽  
Optic Axis ◽  
Two Dimensional ◽  
Structural System ◽  
Dynamic Tests ◽  
Perspective Distortion ◽  
Displacement Sensors ◽  
System Properties ◽  
Contact Displacement

The availability of a suitable data acquisition sensor network is a key implementation issue to link models with real world structures. Non-contact displacement sensors should be preferred since they do not change the system properties. A two-dimensional vision-based displacement measurement sensor is the focus of this contribution. In particular, the perspective distortion introduced by the angle between the optic axis of the camera and the normal to the plane in which the structural system deforms is considered. A two-dimensional affine transformation is utilized to eliminate the distortion from the recorded to the distortion-free image. The results of a laboratory experiment show the potential of the proposed approach.

scholarly journals Laser Displacement Sensors for Wind Tunnel Model Position Measurements

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4085 ◽  
Author(s):  
Matthew Kuester ◽  
Nanyaporn Intaratep ◽  
Aurélien Borgoltz
Keyword(s):  
Wind Tunnel ◽  
Angle Of Attack ◽  
Pitching Moment ◽  
Two Dimensional ◽  
Temperature Drift ◽  
Wind Tunnel Model ◽  
Multiple Sensors ◽  
Displacement Sensors ◽  
Tunnel Model ◽  
Linear Encoder

Wind tunnel measurements of two-dimensional wing sections, or airfoils, are the building block of aerodynamic predictions for many aerodynamic applications. In these experiments, the forces and pitching moment on the airfoil are measured as a function of the orientation of the airfoil relative to the incoming airflow. Small changes in this angle (called the angle of attack, or α ) can create significant changes in the forces and moments, so accurately measuring the angle of attack is critical in these experiments. This work describes the implementation of laser displacement sensors in a wind tunnel; the sensors measured the distance between the wind tunnel walls and the airfoil, which was then used to calculate the model position. The uncertainty in the measured laser distances, based on the sensor resolution and temperature drift, is comparable to the uncertainty in traditional linear encoder measurements. Distances from multiple sensors showed small, but statistically significant, amounts of model deflection and rotation that would otherwise not have been detected, allowing for an improved angle of attack measurement.

Square Layout Four-Point Method for Two-Dimensional Profile Measurement and Self-Calibration Method of Zero-Adjustment Error

2018 ◽  
Vol 12 (5) ◽  
pp. 707-713 ◽  
Author(s):  
Hiroki Shimizu ◽  
◽  
Ryousuke Yamashita ◽  
Takuya Hashiguchi ◽  
Tasuku Miyata ◽  
...  
Keyword(s):  
Calibration Method ◽  
Recurrence Equation ◽  
Profile Measurement ◽  
Two Dimensional ◽  
Measuring Point ◽  
Self Calibration ◽  
Displacement Sensors ◽  
Adjustment Error ◽  
Scan Line ◽  
Height Data

An on-machine measurement method, called the square-layout four-point (SLFP) method with angle compensation, for evaluating two-dimensional (2-D) profiles of flat machined surfaces is proposed. In this method, four displacement sensors are arranged in a square and mounted to the scanning table of a 2-D stage. For measuring the 2-D profile of a target plane, height data corresponding to all measuring points are acquired by means of the raster scanning motion. At the same time, pitching data of the first primary scan line and rolling data of the first subsidiary scan line are monitored by means of two auto-collimators to compensate for major profile errors that arise out of the posture error. Use of the SLFP method facilitates connection of the results of straightness-measurements results obtained for each scanning line by using two additional sensors and rolling data of the first subsidiary scan line. Specifically, the height of a measuring point is calculated by means of a recurrence equation using three predetermined height data for adjacent points in conjunction with data acquired by the four displacement sensors. Results of the numerical simulation performed in this study demonstrate higher efficiency of the SLFP method with angle compensation. During actual measurement, however, it is difficult to perfectly align inline the origin height of each displacement sensor. With regard to the SLFP method, zero-adjustment error is defined as the relative height of a sensor’s origin with respect to the plane comprising origins of the other three sensors. This error accumulates in proportion to number of times the recurrence equation is applied. Simulation results containing the zero-adjustment error demonstrate that accumulation of the said error results in unignorable distortion of measurement results. Therefore, a new self-calibration method for the zero-adjustment error has been proposed. During 2-D profile measurement, two different calculation paths – the raster scan path and orthogonal path – can be used to determine the height of a measurement point. Although heights determined through use of the two paths must ideally be equal, they are observed to be different because accumulated zero-adjustment errors for the two paths are different. In view of this result, the zero-adjustment error can be calculated backwards and calibrated. Validity of the calibration method has been confirmed via simulations and experiments.

scholarly journals Experiments on Fiber Concrete Foundation Slabs in Interaction with the Subsoil

2020 ◽  
Vol 12 (9) ◽  
pp. 3939 ◽  
Author(s):  
Radim Cajka ◽  
Zuzana Marcalikova ◽  
Marie Kozielova ◽  
Pavlina Mateckova ◽  
Oldrich Sucharda
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Laboratory Tests ◽  
Three Dimensional ◽  
Concrete Slabs ◽  
Two Dimensional ◽  
Load Step ◽  
Loading Test ◽  
Displacement Sensors ◽  
Fiber Concrete

This article focuses on researching the interactions of fiber concrete slabs with subsoil. The experimental series includes four slabs made of fiber concrete with different dosages of fibers, from 0 to 75 kg/m3. The slabs were exposed to a loading test on a specialized loading frame. The laboratory tests for detailed descriptions of the fiber concrete’s mechanical properties were also an integral part of the experiments, including tests of the compressive strength, the modulus of elasticity, and split and bending tensile strength. Each slab’s deformation in a particular load step was evaluated in two-dimensional (2D) sections based on data measured with displacement sensors and in three-dimensional (3D) charts with the use of interpolation.

CCD-based two-dimensional pneumatic arm control system

2009 ◽  
Vol 223 (5) ◽  
pp. 585-590 ◽  
Author(s):  
Y-T Wang ◽  
R-H Wong ◽  
J-H Lo
Keyword(s):  
Control System ◽  
Fuzzy Controller ◽  
Sliding Mode ◽  
Computational Effort ◽  
Fuzzy Rules ◽  
Two Dimensional ◽  
Control Performance ◽  
Measuring Process ◽  
Learning Mechanism ◽  
Displacement Sensors

This paper proposes a non-contacted CCD to replace contacted displacement sensors in a two-dimensional (2D) pneumatic arm control system. The CCD is used to capture images which are then transformed to X- Y coordinates that are used as feedback signals. Since the measuring process requires considerable computational effort a self-organizing sliding mode fuzzy controller is proposed to simplify the fuzzy rules and reduce the computer load. The proposed learning mechanism can be used to optimize the fuzzy rules online and improve the control performance. Experimental data is provided on the trajectory tracking performances of the CCD-based and encoder-based 2D pneumatic arms.

scholarly journals A Novel Online Detection System for Wheelset Size in Railway Transportation

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Xiaoqing Cheng ◽  
Yuejian Chen ◽  
Zongyi Xing ◽  
Yifan Li ◽  
Yong Qin
Keyword(s):  
Field Experiments ◽  
Detection System ◽  
Calibration Method ◽  
Two Dimensional ◽  
Online Detection ◽  
Railway Transportation ◽  
Maintenance Costs ◽  
One Dimensional ◽  
Displacement Sensors ◽  
Railway Operation

The online detection of wheelset size has important implications for ensuring the safety of railway operation and decreasing the maintenance costs. Based on laser displacement sensors (LDS), a novel online detection system of the wheel size is proposed using only six two-dimensional LDS and two one-dimensional LDS. The calculation principles of tread profile and wheel diameter are given, as well as the calibration method. Errors induced by wheel-rail vibration, misalignment, sensor noise, S-shape running, and wheelset differential are also analyzed. After system implementation, field experiments were performed using both standard wheel and several real trains. It turns out that the detection uncertainty of flange width and height is 0.1 mm and wheel diameter 0.3 mm, which can meet the requirements of maintenance.

Spectrophotometric measurements of objective-prism spectra

1966 ◽  
Vol 24 ◽  
pp. 118-119
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Progress Report ◽  
Two Dimensional ◽  
Objective Prism ◽  
Made In

I should like to give you a very condensed progress report on some spectrophotometric measurements of objective-prism spectra made in collaboration with H. Leicher at Bonn. The procedure used is almost completely automatic. The measurements are made with the help of a semi-automatic fully digitized registering microphotometer constructed by Hög-Hamburg. The reductions are carried out with the aid of a number of interconnected programmes written for the computer IBM 7090, beginning with the output of the photometer in the form of punched cards and ending with the printing-out of the final two-dimensional classifications.

Introductory paper

1966 ◽  
Vol 24 ◽  
pp. 3-5
Author(s):  
W. W. Morgan
Keyword(s):  
Line Intensity ◽  
Classification Scheme ◽  
Two Dimensional ◽  
Spectral Classification ◽  
Dimensional Array ◽  
Rr Lyrae ◽  
Metallic Line ◽  
Introductory Paper ◽  
Parameter Varying ◽  
Definition Of

1. The definition of “normal” stars in spectral classification changes with time; at the time of the publication of theYerkes Spectral Atlasthe term “normal” was applied to stars whose spectra could be fitted smoothly into a two-dimensional array. Thus, at that time, weak-lined spectra (RR Lyrae and HD 140283) would have been considered peculiar. At the present time we would tend to classify such spectra as “normal”—in a more complicated classification scheme which would have a parameter varying with metallic-line intensity within a specific spectral subdivision.

A one-dimensional self-gravitating stellar gas

1966 ◽  
Vol 25 ◽  
pp. 46-48 ◽  
Author(s):  
M. Lecar
Keyword(s):  
Gravitational Field ◽  
Phase Space ◽  
Motion Picture ◽  
Space Distribution ◽  
Two Dimensional ◽  
One Dimensional ◽  
Phase Space Distribution ◽  
Dimensional Phase Space ◽  
The Mean

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.

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