Real-time stage position measurement with nanometer-scale accuracy

1997 ◽  
Author(s):  
Philip D. Henshaw ◽  
Donald P. DeGloria ◽  
Sandra A. Kelly ◽  
Robert F. Dillon
Keyword(s):  
Real Time ◽  
Nanometer Scale ◽  
Position Measurement ◽  
Time Stage

Real-time visualization and sub-diffraction limit localization of nanometer-scale pore formation by dielectric breakdown

Nanoscale ◽  
2017 ◽  
Vol 9 (42) ◽  
pp. 16437-16445 ◽  
Author(s):  
Adam Zrehen ◽  
Tal Gilboa ◽  
Amit Meller
Keyword(s):  
Real Time ◽  
Pore Formation ◽  
Dielectric Breakdown ◽  
Diffraction Limit ◽  
Nanometer Scale ◽  
Optical Monitoring ◽  
Real Time Visualization

Herein, we introduce synchronous, real-time, electro-optical monitoring of nanopore formation by DB.

scholarly journals A Multi-Sensor Based Roadheader Positioning Model and Arbitrary Tunnel Cross Section Automatic Cutting

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4955
Author(s):  
Changqing Yan ◽  
Wenxiao Zhao ◽  
Xinming Lu
Keyword(s):  
Real Time ◽  
Cross Section ◽  
Trajectory Planning ◽  
Hydraulic Cylinder ◽  
High Accuracy ◽  
Position Measurement ◽  
Coordinate Measurement ◽  
Positioning Method ◽  
Planning Methods ◽  
Tunnel Cross Section

Autonomous posture detection and self-localization of roadheaders is the key to automatic tunneling and roadheader robotization. In this paper, a multi-sensor based positioning method, involving an inertial system for altitude angles measurement, total station for coordinate measurement, and sensors for measuring the real-time length of the hydraulic cylinder is presented for roadheader position measurement and posture detection. Based on this method, a positioning model for roadheader and cutter positioning is developed. Additionally, flexible trajectory planning methods are provided for automatic cutting. Based on the positioning model and the trajectory planning methods, an automatic cutting procedure is proposed and applied in practical tunneling. The experimental results verify the high accuracy and efficiency of both the positioning method and the model. Furthermore, it is indicated that arbitrary shapes can be generated automatically and precisely according to the planned trajectory, employing the automatic cutting procedure. Therefore, unmanned tunneling can be realized by employing the proposed automatic cutting process.

Optimization of Rapid State Estimation in Structures Subjected to High-Rate Boundary Change

2020 ◽  
Author(s):  
James Scheppegrell ◽  
Adriane G. Moura ◽  
Jacob Dodson ◽  
Austin Downey
Keyword(s):  
Frequency Response ◽  
State Estimation ◽  
Real Time ◽  
Performance Metrics ◽  
Numerical Models ◽  
Vertical Axis ◽  
High Rate ◽  
Position Measurement ◽  
Data Set ◽  
Variable Boundary

Abstract Many structures are subjected to varying forces, moving boundaries, and other dynamic conditions. Whether part of a vehicle, building, or active energy mitigation device, data on such changes can represent useful knowledge, but also presents challenges in its collection and analysis. In systems where changes occur rapidly, assessment of the system’s state within a useful time span is required to enable an appropriate response before the system’s state changes further. Rapid state estimation is especially important but poses unique difficulties. In determining the state of a structural system subjected to high-rate dynamic changes, measuring the frequency response is one method that can be used to draw inferences, provided the system is adequately understood and defined. The work presented here is the result of an investigation into methods to determine the frequency response, and thus state, of a structure subjected to high-rate boundary changes in real-time. In order to facilitate development, the Air Force Research Laboratory created the DROPBEAR, a testbed with an oscillating beam subjected to a continuously variable boundary condition. One end of the beam is held by a stationary fixed support, while a pinned support is able to move along the beam’s length. The free end of the beam structure is instrumented with acceleration, velocity, and position sensors measuring the beam’s vertical axis. Direct position measurement of the pin location is also taken to provide a reference for comparison with numerical models. This work presents a numerical investigation into methods for extracting the frequency response of a structure in real-time. An FFT based method with a rolling window is used to track the frequency of a data set generated to represent the range of the DROPBEAR, and is run with multiple window lengths. The frequency precision and latency of the FFT method is analyzed in each configuration. A specialized frequency extraction technique, Delayed Comparison Error Minimization, is implemented with parameters optimized for the frequency range of interest. The performance metrics of latency and precision are analyzed and compared to the baseline rolling FFT method results, and applicability is discussed.

The application of positioning reduction in the real-time stage of the Chang'E-2 project

2011 ◽  
Vol 41 (7) ◽  
pp. 889-895 ◽  
Author(s):  
JinLing LI ◽  
Li LIU ◽  
ZhiHan QIAN ◽  
WeiMin ZHENG
Keyword(s):  
Real Time ◽  
The Real ◽  
Time Stage

scholarly journals Store Separation: Photogrammetric Solution for the Static Ejection Test

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Luiz Eduardo Guarino de Vasconcelos ◽  
Nelson Paiva Oliveira Leite ◽  
André Yoshimi Kusumoto ◽  
Leandro Roberto ◽  
Cristina Moniz Araujo Lopes
Keyword(s):  
Real Time ◽  
Analytical Model ◽  
Three Dimensional ◽  
Flight Test ◽  
3D Analysis ◽  
Trajectory Data ◽  
Position Measurement ◽  
Advantages And Disadvantages ◽  
Store Separation ◽  
Development And Validation

The process of developing and certifying aircraft and aeronautical systems requires the execution of experimental flight test campaigns to determine the actual characteristics of the system being developed and/or validated. In this process, there are many campaigns that are inherently dangerous, such as the store separation. In this particular case, the greatest risk is the collision of the store with the fuselage of the aircraft. To mitigate the risks of this campaign, it is necessary to compare the actual trajectory of a separation with its simulated estimates. With such information, it is possible to decide whether the next store release can be done with the required safety and/or whether the model used to estimate the separation trajectory is valid or not. Consequently, exact determination of the trajectory of the separation is necessary. Store separation is a strategic, relevant, and complex process for all nations. The two main techniques for determining the quantitative store trajectory data with 6DoF (six degrees of freedom) are photogrammetry and instrumented telemetry packages (data obtained from inertial sensors that are installed in the store). Each presents advantages and disadvantages. In regard to photogrammetry, several market solutions can be used to perform these tests. However, the result of the separation trajectory is only obtained after the test flight, and therefore, it is not possible to safely carry out more than one on the same flight. In this context, the development and validation of a solution that will allow the realization of near real-time separation analysis are in fact an innovative and original work. This paper discusses the development and validation, through actual static ejection tests, of the components that will compose a new onboard optical trajectory system for use in store separation campaigns. This solution includes the implementation of a three-dimensional (3D) calibration field that allows calibration of the optical assembly with just one photo per optical assembly, development of a complete analytical model for camera calibration, and development of specific software for identification and tracking of targets in two-dimensional (2D) coordinate images and three-dimensional (3D) coordinate trajectory calculation. In relation to the calibration, the analytical model is based on a pinhole type camera and considers its intrinsic parameters. This allowed for a mean square error smaller than ±3.9 pixels @1σ. The 3D analysis software for 6DoF trajectory expression was developed using photogrammetry techniques and absolute orientation. The uncertainty associated with the position measurement of each of the markers varies from ±0.02 mm to ±8.00 mm @1σ, depending on the geometry of the viewing angles. The experiments were carried out at IPEV (Flight Test Research Institute)/Brazil, and the results were considered satisfactory. We advocate that the knowledge gained through this research contributes to the development of new methods that permit almost real-time analysis in store separation tests.

scholarly journals An Online Calibration Method for a Galvanometric System Based on Wavelet Kernel ELM

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1353 ◽  
Author(s):  
Wugang Zhang ◽  
Wei Guo ◽  
Chuanwei Zhang ◽  
Shuanfeng Zhao
Keyword(s):  
Real Time ◽  
Calibration Method ◽  
System Structure ◽  
Data Sets ◽  
Position Measurement ◽  
Online Calibration ◽  
Time Performance ◽  
Calibration Methods ◽  
Testing Data ◽  
Mean Square Errors

The online calibration method of a two-dimensional (2D) galvanometer requires both high precision and better real-time performance to meet the needs of moving target position measurement, which presents some challenges for traditional calibration methods. In this paper, a new online calibration method is proposed using the wavelet kernel extreme learning machine (KELM). Firstly, a system structure is created and its experiment setup is established. The online calibration method is then analyzed based on a wavelet KELM algorithm. Finally, the acquisition methods of the training data are set, two groups of testing data sets are presented, and the verification method is described. The calibration effects of the existing methods and wavelet KELM methods are compared in terms of both accuracy and speed. The results show that, for the two testing data sets, the root mean square errors (RMSE) of the Mexican Hat wavelet KELM are reduced by 16.4% and 38.6%, respectively, which are smaller than that of the original ELM, and the standard deviations (Sd) are reduced by 19.2% and 36.6%, respectively, indicating the proposed method has better generalization and noise suppression performance for the nonlinear samples of the 2D galvanometer. Although the online operation time of KELM is longer than ELM, due to the complexity of the wavelet kernel, it still has better real-time performance.

Development of laboratory devices for real-time measurement of object 3D position using stereo cameras

2021 ◽  
Vol 57 (2) ◽  
pp. 025006
Author(s):  
Sigit Ristanto ◽  
Waskito Nugroho ◽  
Eko Sulistya ◽  
Gede B Suparta
Keyword(s):  
Real Time ◽  
Template Matching ◽  
Physical Phenomenon ◽  
Stereo Image ◽  
Position Measurement ◽  
Average Delay ◽  
Object Position ◽  
Stereo Camera ◽  
3D Object ◽  
Object Distance

Abstract Measuring the 3D position at any time of a given object in real-time automatically and well documented to understand a physical phenomenon is essential. Exploring a stereo camera in developing 3D images is very intriguing since a 3D image perception generated by a stereo image may be reprojected back to generate a 3D object position at a specific time. This research aimed to develop a device and measure the 3D object position in real-time using a stereo camera. The device was constructed from a stereo camera, tripod, and a mini-PC. Calibration was carried out for position measurement in X, Y, and Z directions based on the disparity in the two images. Then, a simple 3D position measurement was carried out based on the calibration results. Also, whether the measurement was in real-time was justified. By applying template matching and triangulation algorithms on those two images, the object position in the 3D coordinate was calculated and recorded automatically. The disparity resolution characteristic of the stereo camera was obtained varied from 132 pixels to 58 pixels for an object distance to the camera from 30 cm to 70 cm. This setup could measure the 3D object position in real-time with an average delay time of less than 50 ms, using a notebook and a mini-PC. The 3D position measurement can be performed in real-time along with automatic documentation. Upon the stereo camera specifications used in this experiment, the maximum accuracy of the measurement in X, Y, and Z directions are ΔX = 0.6 cm, ΔY = 0.2 cm, and ΔZ = 0.8 cm at the measurement range of 30 cm–60 cm. This research is expected to provide new insights in the development of laboratory tools for learning physics, especially mechanics in schools and colleges.

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