MULTIRATE & NONLINEAR CONTROLLERS FOR LOW-COST LASER TRACKING SYSTEMS

Electricity is one of the most crucial resources that drives any given nation’s growth and development. The latest Sustainable Development Goals report indicates Africa still has a high deficit in electricity generation. Concentrating solar power seems to be a potential option to fill the deficit. That is because most of the components of concentrating solar power plants are readily available on the African market at affordable prices, and there are qualified local persons to build the plants. Pilot micro-concentrating solar power plants have been implemented in Sub-Saharan Africa and have shown promising results that could be expanded and leveraged for large-scale electricity generation. An assessment of a pilot concentrating solar power plant in the sub-region noticed one noteworthy obstacle that is the failure of the tracking system to reduce the operating energy cost of running the tracking control system and improve the multifaceted heliostat focusing behavior. This paper highlights the energy situation and the current development in concentrating solar power technology research in Africa. The paper also presents a comprehensive review of the state-of-the-art solar tracking systems for central receiver systems to illustrate the current direction of research regarding the design of low-cost tracking systems in terms of computational complexity, energy consumption, and heliostat alignment accuracy.

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Investigating the Use of Two Low Cost Eye Tracking Systems for Detecting Pupillary Response to Changes in Mental Workload

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1541931213601009 ◽

2016 ◽

Vol 60 (1) ◽

pp. 37-41 ◽

Cited By ~ 20

Author(s):

Joseph Coyne ◽

Ciara Sibley

Keyword(s):

Eye Tracking ◽

Pupil Size ◽

Mental Workload ◽

Low Cost ◽

Digit Span ◽

Pupillary Response ◽

Background Luminance ◽

Tracking Systems ◽

Lighting Conditions ◽

Size Data

Eye tracking technologies are being utilized at increasing rates within industry and research due to the very recent availability of low cost systems. This paper presents results from a study assessing two eye tracking systems, Gazepoint GP3 and Eye Tribe, both of which are available for under $500 and provide streaming gaze and pupil size data. The emphasis of this research was in evaluating the ability of these eye trackers to identify changes in pupil size which occur as a function of variations in lighting conditions as well as those associated with workload. Ten volunteers participated in an experiment in which a digit span task was employed to manipulate workload as user’s fixated on a monitor which varied in background luminance (black, gray and white). Results revealed that both systems were able to significantly differentiate pupil size differences in high and low workload trials and changes due to the monitor’s luminance. These findings are exceedingly promising for human factors researchers, as they open up the opportunity to augment studies with non-obtrusive, streaming measures of mental workload with technologies available for as little as $100.

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Sandia National Labs' precision laser tracking systems

10.1117/12.273366 ◽

1997 ◽

Author(s):

Duane L. Patrick

Keyword(s):

Tracking Systems ◽

Laser Tracking

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Modeling and simulation of laser tracking systems

Kybernetes ◽

10.1108/03684921211275207 ◽

2012 ◽

Vol 41 (9) ◽

pp. 1192-1199 ◽

Cited By ~ 2

Author(s):

Liu Wanli ◽

Qu Xinghua ◽

Ouyang Jianfei

Keyword(s):

Modeling And Simulation ◽

Tracking Systems ◽

Laser Tracking

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Assessment of Influence of Sample Averaging on Accuracy of Point Coordinates Measurement Performed Using Laser Tracking Systems

Advances in Science and Technology – Research Journal ◽

10.12913/22998624/114186 ◽

2019 ◽

Vol 13 (4) ◽

pp. 94-99

Author(s):

Maciej Gruza ◽

Piotr Gąska ◽

Adam Gąska ◽

Wiktor Harmatys ◽

Michał Jedynak ◽

...

Keyword(s):

Tracking Systems ◽

Laser Tracking

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The ATS-F/NIMBUS-E Tracking Experiment

Symposium - International Astronomical Union ◽

10.1017/s0074180900098168 ◽

1972 ◽

Vol 48 ◽

pp. 112-120 ◽

Cited By ~ 2

Author(s):

F. O. von Bun

Keyword(s):

Integration Time ◽

Time Interval ◽

Tracking Systems ◽

Tracking Errors ◽

Original Intent ◽

Laser Tracking ◽

Ground Station ◽

Error Analyses ◽

Range Rate

In this paper the objective of the ATS-F/NIMBUS-E Tracking Experiment, the first of such kind, is presented. Specifically, this experiment has a two-fold purpose: First, to gain experience in the practical use of satellite-to-satellite range and range rate data for very accurate orbit determination (this was its original intent); and second, to evaluate the real usefulness of such a technique for geodetic studies despite the fact that the 1000 km NIMBUS orbit is not ideally suited for such a purpose.The accuracies of the tracking systems of the satellite-to-satellite and satellite-to-ground link (ATS-F to the Rosman, N.C. ground station) will be ~ 0.035 cm/s in range rate and ~ 1 m in range – utilizing a 10 s integration time. With these values one obtains, based upon performed error analyses, orbit height errors in the order of 0.1 to 0.3 m for the near earth orbiting NIMBUS spacecraft. This experiment will therefore hopefully prove to be a significant first step for future Earth applications spacecraft carrying altimeters systems for measuring ocean height variations.In addition, laser corner reflectors placed on board the ATS-F will make a total independent position determination of this spacecraft to approximately 15 m to 30 m possible, assuming that the location errors of four laser tracking stations used to determine the orbit are about 3 m or 5 m in each component respectively, with laser ranging system noise errors of 1.2 m and bias errors of 0.15 m. A small position error of the ATS-F, the ‘orbiting tracking station’ is essential in order to make full usage of the small satellite-to-satellite tracking errors mentioned.For purpose of geodetic studies, one of the final goals, range rate variations of 0.1 cm/s or less corresponding to surface gravity anomaly of 20 mgal or less (over a half-width of 100 km on the Earth surface), will have to be measured during a time interval of approximately, say, 30–60 s. These values are within the range of the planned tracking systems accuracies for ATS-F and NIMBUS-E.

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Smithsonian Astrophysical Observatory laser tracking systems

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1977.0016 ◽

1977 ◽

Vol 284 (1326) ◽

pp. 431-442 ◽

Cited By ~ 5

Keyword(s):

Laser Pulse ◽

Pulse Width ◽

Tracking Systems ◽

Wave Shape ◽

Geophysical Research ◽

Laser Tracking ◽

Electronic Pulse ◽

And Performance ◽

Earth Dynamics ◽

Initial Results

The Smithsonian Astrophysical Observatory operates four laser satellite-ranging systems in support of geodetic and geophysical research. The lasers-located in Brazil, Peru, Australia, and Arizona-have been in operation for more than 5 years and have provided ranging data at accuracy levels of a metre or better. To meet new requirements in geophysics, these systems are now being upgraded to improve range accuracy and performance. The lasers are being equipped with electronic pulse processors, to analyse returnpulse wave shape, and pulse choppers, to reduce laser pulse width. Initial results indicate that the upgraded ranging system hardware will meet the decimetre ranging-accuracy requirements for the Geos 3 and Seasat satellites and for Earth-dynamics projects based on satellites such as Starlette.

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Can low-cost motion-tracking systems substitute a Polhemus system when researching social motor coordination in children?

Behavior Research Methods ◽

10.3758/s13428-016-0733-1 ◽

2016 ◽

Vol 49 (2) ◽

pp. 588-601 ◽

Cited By ~ 10

Author(s):

Veronica Romero ◽

Joseph Amaral ◽

Paula Fitzpatrick ◽

R. C. Schmidt ◽

Amie W. Duncan ◽

...

Keyword(s):

Motion Tracking ◽

Motor Coordination ◽

Low Cost ◽

Tracking Systems ◽

Social Motor Coordination

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Modeling and Sensitivity Analysis of Laser Tracking Systems by Skew-Ray Tracing Method

Journal of Manufacturing Science and Engineering ◽

10.1115/1.1954790 ◽

2004 ◽

Vol 127 (3) ◽

pp. 654-662 ◽

Cited By ~ 10

Author(s):

Psang Dain Lin ◽

Chia-Hung Lu

Keyword(s):

Sensitivity Analysis ◽

Ray Tracing ◽

Tracking System ◽

Tracking Systems ◽

Position Measurement ◽

Ray Tracing Method ◽

Laser Tracking ◽

Corner Cube ◽

Alignment Errors ◽

Tracing Method

Laser tracking systems, such as the Leica LTD 500, are used for precision position measurement of large or distant objects, for example, the alignment of aircraft wings or bridge girders during assembly. A laser tracker’s performance is theoretically better than other common metrology equipment, such as coordinate measuring machines (CMMs). It is desirable that a flexible laser tracking system replaces the standard CMM, but measurement accuracy is highly dependent on the accuracy of its rotating mirror mechanism and its link dimension variance during tracker manufacture and assembly. Therefore this study presents a skew-ray tracing method for modeling and sensitivity analysis of laser tracking systems. First, the geometric relations of position-detector and interferometer readings are derived in terms of the laser tracker’s parameters using skew-ray tracing method. Effects of corner-cube alignment errors on sensor readings are also investigated theoretically, and it is found that misalignment of the corner-cube causes errors in path length and, therefore, misestimation of distance. Effects of mirror mechanism dimension errors are also investigated by sensitivity analysis. This study will be of use to theoretical and practical studies involving the modeling, design, and use of laser tracking systems and similar devices.

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