Alignment-and-metrological facility for fine adjustment of antenna linear and angular position during spacecraft assembly

2019 ◽  
pp. 48-56
Author(s):  
Marina A. FILINA ◽  
Nadezhda Yu. KOSTIKOVA ◽  
Vladimir V. PETROV ◽  
Gleb B. BUZIK ◽  
Yuriy V. ZUEV ◽  
...  
Keyword(s):  
High Precision ◽  
Angular Position ◽  
Antenna System ◽  
Measuring System ◽  
Coordinate Measurement ◽  
Pointing Device ◽  
Human Effort ◽  
Spatial Positioning ◽  
Fine Adjustment ◽  
Rule Out

The paper discusses issues involved in fine adjustment of the linear and angular position of antenna system reflectors on a spacecraft (SC) during its assembly using an alignment-and-metrology facility that has been developed, which consists of a 6-DOF pointing device and a laser coordinate measurement tracker. Achieving the specified linear and angular positions of antenna system elements in the SC datum reference frame, reducing human effort and time needed to perform this processing operation is an important task when building a spacecraft. To address this problem, a procedure was developed and tried out during an actual SC assembly consisting in the joint use of the 6-DOF pointing device Hexapod PM-mkm-P and the high-precision laser tracker Leica AT 403 for measuring the coordinates. An algorithm was developed for hardware/software interfacing between elements of the alignment-and-metrology facility, which provides iterative linear and angular positioning of the antenna reflectors in a closed loop with a feedback. The paper discusses sources of errors and the way to minimize their effect on the operation of various types of pointing using continuous monitoring by means of an external measuring system. The developed alignment-and-metrology facility provided high-precision spatial positioning of antenna elements in the SC coordinate system, which made it possible to rule out any errors by operator/installation worker during alignment and significantly reduce the time needed to perform the said operation. Key words: spacecraft, antenna alignment, 6-DOF hexapod-type platform with parallel kinematics, Gough-Stewart platform, laser coordinate measuring system.

In-orbit deployment of a high precision mesh antenna system for space VLBI mission

1998 ◽  
Author(s):  
M. Natori ◽  
T. Takano ◽  
A. Ohnishi ◽  
K. Miyoshi ◽  
T. Inoue ◽  
...  
Keyword(s):  
High Precision ◽  
Antenna System

A High-Precision Absolute Angular Position Sensor With Vernier Capacitive Arrays Based on Time Grating

2019 ◽  
Vol 19 (19) ◽  
pp. 8626-8634 ◽  
Author(s):  
Hongji Pu ◽  
Hewen Wang ◽  
Xiaokang Liu ◽  
Zhicheng Yu ◽  
Kai Peng
Keyword(s):  
High Precision ◽  
Angular Position ◽  
Position Sensor

P2674Rapid rule-out of myocardial infarction with a novel high precision point-of-care troponin assay appears safe and effective

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
S Aldous ◽  
J Pickering ◽  
J Young ◽  
P George ◽  
A Watson ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Decision Making ◽  
Emergency Department ◽  
Chest Pain ◽  
High Precision ◽  
Primary Outcome ◽  
Point Of Care ◽  
High Sensitivity ◽  
Research Fellowship ◽  
Rule Out

Abstract Background High sensitivity troponin assays were developed to improve analytical sensitivity and precision at the decision cut-points for the diagnosis and rule out of acute myocardial infarction (AMI). Central laboratory assays have achieved this but point of care assays, which have the ability to accelerate decision making due to much shorter turnaround times, have remained lacking. Purpose To ascertain the threshold for decision making and subsequent clinical utility for ruling out AMI on presentation in patients attending the emergency department acutely with chest pain, using a high precision point of care troponin assay (TnI Nx), (i-STAT, Abbott). Methods We measured arrival TnI-Nx concentrations in stored plasma samples in adults presenting acutely to the emergency department with chest pain. The primary outcome was an AMI or cardiac death on index admission or within 30 days. We used 2000 bootstrapped data sets to derive and validate a suitable threshold for TnI-Nx before calculating diagnostic test performance. We pre-specified this threshold must have a <1% false negative rate for the primary outcome. We compared this with a core laboratory high sensitivity troponin I (hs-TnI) (Abbott Architect) using the early rule-out cut-point (European Society of Cardiology) at the limit of detection (2 ng/L). Results We recruited 1320 patients of whom 192 (14.1%) had the primary outcome. The TnI-Nx threshold was determined to be 8 ng/L with subsequent sensitivity of 99.0% (95% confidence interval: 97.3% to 100%), negative predictive value of 99.7% (99.2% to 100%) and specificity of 59.0% (56.0% to 62.0%). The hs-TnI had a sensitivity of 99.5% (98.2% to 100%), negative predictive value of 99.7% (99.0% to 100%), and specificity of 28.4% (25.8% to 31.2%) at 2ng/L. Conclusion A high precision point of care assay, TnI-Nx, with a decision threshold of 8ng/L, has comparable rule out performance compared with a core laboratory high sensitivity assay and therefore could potentially be used for early decision making in the assessment of acute chest pain. Acknowledgement/Funding Research grant from Abbott Point of Care. Senior Research Fellowship from ECF, CMRF and CDHB. Clinical Research Fellowship from NZ HRC

scholarly journals MODELING OF HIGH PRECISION POSITIONING SYSTEM / DIDELIO TIKSLUMO PADĖTIES NUSTATYMO SISTEMOS MODELIAVIMAS

2013 ◽  
Vol 5 (6) ◽  
pp. 633-637
Author(s):  
Giedrius Augustinavičius ◽  
Audrius Čereška
Keyword(s):  
Mathematical Model ◽  
High Precision ◽  
Positioning System ◽  
Reduction Mechanism ◽  
Precision Positioning ◽  
Analytical Approaches ◽  
The Mathematical Model ◽  
Architecture Optimization ◽  
Fine Adjustment

This paper presents the modeling of a flexure-based precisionpositioning system for micro-positioning uses. The positioningsystem is featured with monolithic architecture, flexure-basedjoints and ultra fine adjustment screws. Its workspace has beenevaluated via analytical approaches. Reduction mechanism isoptimally designed. The mathematical model of the positioningsystem has been derived, which is verified by resorting to finiteelement analysis (FEA). The established analytical and (FEA)models are helpful for a reliable architecture optimization andperformance improvement of the positioning system. Santrauka Straipsnyje pristatomas didelio tikslumo centravimo ir niveliavimo padėties nustatymo sistemos su besideformuojančiais mechanizmais kūrimas ir modeliavimas. Padėties nustatymo sistema optimizuota Solidworks Simulation programiniu paketu. Centravimo platformų poslinkiams apskaičiuoti sudarytas matematinis modelis, kurio patikimumas buvo patikrintas taikant baigtinių elementų metodą. Sudaryto matematinio modelio ir rezultatų, gautų pritaikius baigtinių elementų metodą, skirtumai buvo mažesni nei 10 %. Pasiūlyta modeliavimo metodika gali būti taikoma kuriant padėties nustatymo sistemas su besideformuojančiais mechanizmais.

Research on the High Precision Laser Line Scanning Measuring System

2007 ◽  
Vol 339 ◽  
pp. 131-135 ◽  
Author(s):  
Jian Jun Ding ◽  
Zhuang De Jiang ◽  
Bing Li ◽  
Jun Jie Guo
Keyword(s):  
High Precision ◽  
Laser Scanning ◽  
Laser Line ◽  
Measuring System ◽  
Surface Measurement ◽  
Iteration Algorithm ◽  
Reconstruction Method ◽  
Loop Feedback ◽  
Axis Position ◽  
Line Scanning

Rapid reverse technology is one of the key technologies with which the enterprises develop new product and occupy the market rapidly. How to realize the reverse measurement and CAD geometry reconstruction rapidly and accurately is always the most important focus for the researchers. Based on the laser scanning technology, the realization principle of the laser line scanning measuring system is presented and the approaches to improve the precision are also analysed in the paper. The self-adaptation adjustment of the probe position can move the light knife image to the optimal imaging area of the CCD according to the calibration result, which will ensure the measurement precision of the CCD image. With the inner velocity loop and outer position loop feedback control, the simple axis position precision of the mechanical system can be controlled within 5um. In order to pick up the points of the light knife centre rationally and exactly, the reconstruction-disperse iteration algorithm is put forward. After processed by different iteration times, the optimal points can be obtained. The reconstruction method of curve and surface based on NURBS is also given. The paper presents the application and realization of the system at last, which realizes the curve and surface measurement with high precision.

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