Closed-Loop Real-Time PNF Position Compensation with a Tracking Laser

Authors: Scott T. McBride, Steven R. Nichols
Publication: EuCAP 2015
Copyright Owner: IEEE

If a planar near-field (PNF) scanner is large and there is insufficient temperature regulation in the chamber to keep ordinary thermal expansion/contraction from causing unacceptable position errors, then consideration must be given to compensation techniques that can adjust for the changes. Thermal expansion/contraction will affect almost everything in the chamber including the floor, the scanner structure, the encoder or position tapes, the AUT support, and the mount for any extra instrument(s) used to measure and correct for position error. Since the temperature will generally cycle several times during a lengthy acquisition, error-correction solutions must account for the dynamic nature of the temperature effects.

This paper describes a new automated tracking-laser compensation subsystem that has been designed and developed for very large horizontal PNF systems. The subsystem is active during the acquisition to account for both static and dynamic errors and compensates for those errors in all three dimensions. The compensation involves both open-loop corrections for repeatable errors with high spatial frequency and closed-loop corrections for dynamic errors with low spatial frequency. To close the loop, laser data are measured at a user-defined interval between scans and each scan that follows the laser measurements is fully compensated. The laser measurements are fully automated with no user interaction required during the acquisition.

The challenges, goals, and assumptions for this development are listed, the high-level implementation concept is described, and resulting measured data are presented.

You have requested a Reprint of an IEEE Paper

Copyright 2015 IEEE. Reprinted from EuCAP 2015 Conference.

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of NSI-MI Technologies' products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to pubs-permissions@ieee.org.

By choosing to view this document, you agree to all provisions of the copyright laws protecting it


Atlanta

1125 Satellite Blvd., Suite 100
Suwanee, GA 30024-4629 USA

+1 678 475 8300
+1 678 542 2601
sales@nsi-mi.com

Los Angeles

19730 Magellan Drive
Torrance, CA 90502-1104 USA

+1 310 525 7000
+1 310 525 7100
sales@nsi-mi.com

NSI-MI UK

Unit 51 Harley Road
Sheffield, S11 9SE UK

+44 7493 235224
sales@nsi-mi.co.uk

EMC+SIPI

New Orleans, LA Finding your local time... 4 Days

Latest Tweets

This site is using cookies for analytical purposes and to provide a better user experience. Read our Privacy Policy for more information.
   OK