Enhancement of RSSI-Based Localization Using an Extended Weighted Centroid Method With Virtual Reference Node Information

2020 ◽  
Vol 15 (4) ◽  
pp. 1879-1897
Author(s):  
Apidet Booranawong ◽  
Kiattisak Sengchuai ◽  
Nattha Jindapetch ◽  
Hiroshi Saito
Keyword(s):  
Centroid Method ◽  
Virtual Reference ◽  
Reference Node

Emergency Positioning Method of Indoor Pedestrian in Non-Cooperative Navigation Environment Based on Virtual Reference Node Array/INS

2020 ◽  
Vol 20 (18) ◽  
pp. 10913-10923
Author(s):  
Yanshun Zhang ◽  
Nan Wang ◽  
Shudi Weng ◽  
Ming Li ◽  
Dong Mou ◽  
...  
Keyword(s):  
Virtual Reference ◽  
Reference Node ◽  
Cooperative Navigation ◽  
Positioning Method

Realization of FIR Prefilter for Virtual Reference Feedback Tuning

2017 ◽  
Vol 137 (7) ◽  
pp. 884-890 ◽  
Author(s):  
Yoshihiro Matsui ◽  
Hideki Ayano ◽  
Shiro Masuda ◽  
Kazushi Nakano
Keyword(s):  
Virtual Reference

Visual Communication: A Study of Library Virtual Reference Icons Online

2013 ◽  
Author(s):  
Martina M. King
Keyword(s):  
Visual Communication ◽  
Visual Representations ◽  
Research Library ◽  
Virtual Reference ◽  
Site Web ◽  
Library Staff ◽  
Selection Of

Libraries use icons (visual representations) on their websites to draw attention to features and services. How are library staff to evaluate their icons? This session reports the results of a thesis study which examines and assesses a selection of virtual reference icons from Association of Research Library websites.Les bibliothèques utilisent des icônes (représentations visuelles) sur leur site Web pour attirer l'attention sur certains éléments et services. Quelle est l'aptitude des employés de bibliothèques pour évaluer ces icônes? Cette séance présente les résultats d'une étude de thèse qui examine et mesure une gamme d'icônes de référence virtuelle trouvés sur les sites Web des membres de l'Association of Research Library. 

scholarly journals Performance Analysis of Surface Reconstruction Algorithms in Vertical Scanning Interferometry Based on Coherence Envelope Detection

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 164
Author(s):  
Dongxu Wu ◽  
Fusheng Liang ◽  
Chengwei Kang ◽  
Fengzhou Fang
Keyword(s):  
Surface Reconstruction ◽  
Measurement Accuracy ◽  
Experimental Studies ◽  
Reconstruction Algorithm ◽  
Low Noise ◽  
Surface Measurement ◽  
Reconstruction Algorithms ◽  
Centroid Method ◽  
Envelope Detection ◽  
Vertical Scanning Interferometry

Optical interferometry plays an important role in the topographical surface measurement and characterization in precision/ultra-precision manufacturing. An appropriate surface reconstruction algorithm is essential in obtaining accurate topography information from the digitized interferograms. However, the performance of a surface reconstruction algorithm in interferometric measurements is influenced by environmental disturbances and system noise. This paper presents a comparative analysis of three algorithms commonly used for coherence envelope detection in vertical scanning interferometry, including the centroid method, fast Fourier transform (FFT), and Hilbert transform (HT). Numerical analysis and experimental studies were carried out to evaluate the performance of different envelope detection algorithms in terms of measurement accuracy, speed, and noise resistance. Step height standards were measured using a developed interferometer and the step profiles were reconstructed by different algorithms. The results show that the centroid method has a higher measurement speed than the FFT and HT methods, but it can only provide acceptable measurement accuracy at a low noise level. The FFT and HT methods outperform the centroid method in terms of noise immunity and measurement accuracy. Even if the FFT and HT methods provide similar measurement accuracy, the HT method has a superior measurement speed compared to the FFT method.

scholarly journals Design and validation of an MPC controller for CMG-based testbed

2021 ◽  
Author(s):  
Matteo Facchino ◽  
Atsushi Totsuka ◽  
Elisa Capello ◽  
Satoshi Satoh ◽  
Giorgio Guglieri ◽  
...  
Keyword(s):  
Predictive Control ◽  
Attitude Control ◽  
High Speed ◽  
Control Method ◽  
Input Constraints ◽  
Virtual Reference ◽  
Control Moment ◽  
Pyramidal Configuration ◽  
Actuation Systems ◽  
Constraints Satisfaction

AbstractIn the last years, Control Moment Gyros (CMGs) are widely used for high-speed attitude control, since they are able to generate larger torque compared to “classical” actuation systems, such as Reaction Wheels . This paper describes the attitude control problem of a spacecraft, using a Model Predictive Control method. The features of the considered linear MPC are: (i) a virtual reference, to guarantee input constraints satisfaction, and (ii) an integrator state as a servo compensator, to reduce the steady-state error. Moreover, the real-time implementability is investigated using an experimental testbed with four CMGs in pyramidal configuration, where the capability of attitude control and the optimization solver for embedded systems are focused on. The effectiveness and the performance of the control system are shown in both simulations and experiments.

scholarly journals HEIGHT DETERMINATION TECHNIQUES FOR THE NEXT NATIONAL HEIGHT SYSTEM OF FINLAND - A CASE STUDY

2015 ◽  
Vol 41 (4) ◽  
pp. 145-155
Author(s):  
Timo Saari ◽  
Markku Poutanen ◽  
Veikko Saaranen ◽  
Harri Kaartinen ◽  
Antero Kukko ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Pilot Project ◽  
Satellite System ◽  
Reference Station ◽  
Virtual Reference ◽  
Precise Levelling ◽  
Height Determination ◽  
Weak Points ◽  
Global Navigation Satellite

Precise levelling is known for its accuracy and reliability in height determination, but the process itself is slow, laborious and expensive. We have started a project to study methods for height determination that could decrease the creation time of national height systems without losing the accuracy and reliability that is needed for them. In the pilot project described here, we study some of the alternative techniques with a pilot field test where we compared them with the precise levelling. The purpose of the test is not to evaluate the mutual superiority or suitability of the techniques, but to establish the background for a larger test and to find strong and weak points of each technique. The techniques chosen for this study were precise levelling, Mobile Laser Scanning (MLS) and Global Navigation Satellite System (GNSS) levelling, which included static Global Positioning System (GPS) and Virtual Reference Station (VRS) measurements. This research highlighted the differences of the studied techniques and gave insights about the framework and procedure for the later experiments. The research will continue in a larger scale, where the suitability of the techniques regarding the height systems is to be determined.

scholarly journals Shaping the future realities of virtual reference

2007 ◽  
Vol 43 (1) ◽  
pp. 1-8
Author(s):  
Marie L. Radford ◽  
Lynn Silipigni Connaway ◽  
Jeffrey Pomerantz
Keyword(s):  
Virtual Reference ◽  
The Future

scholarly journals Research on laser stripe characteristics and center extraction algorithm for desktop laser scanner

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Xiaoquan Shi ◽  
Yazhou Sun ◽  
Haitao Liu ◽  
Linqi Bai ◽  
Chonghao Lin
Keyword(s):  
Laser Scanner ◽  
Bright Spot ◽  
Distribution Characteristics ◽  
Ambient Light ◽  
Centroid Method ◽  
Laser Stripe ◽  
Wide Range ◽  
Laser Scanners ◽  
Extraction Algorithm ◽  
Large Width

AbstractThis study presents laser stripe center extraction algorithm for desktop-level 3D laser scanners. The laser stripe center extraction accuracy is an important factor affecting 3D scanning result. Desktop-level devices should have adaptability of a wide range of scanning objects. In this paper, laser stripe energy distribution characteristics with different laser stripe width, ambient light, materials and colors are obtained by experiments. Experiment results show that waveforms of bright spot, low brightness stripe and stripe with large width are complex or easily disturbed, so the center extraction algorithm of them are studied. The extraction effects of extremum method, gradient method and gray centroid method under different conditions are compared. Based on traditional grayscale value, a weighted grayscale value is proposed to extract laser stripe center. Standard deviations of extracted pixel position and fitting pixel position are calculated by different method with different weighted grayscale value. For different conditions, especially for different ambient light intensity, weight matrix plays an important role to extraction result.

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