Tracker controls development and control architecture for the Hobby-Eberly Telescope Wide Field Upgrade

Mock, Jason R.; Beno, Joe; Rafferty, Tom H.; Cornell, Mark E.

doi:10.1117/12.857458

Tracker controls development and control architecture for the Hobby-Eberly Telescope Wide Field Upgrade

Aug 7, 2010

12 pages

Part of Proceedings, SPIE Astronomical Telescopes + Instrumentation: High Energy, Optical, and Infrared Detectors for Astronomy IV : San Diego, California, June 27-July 2, 2010

Published in:

Proc.SPIE Int.Soc.Opt.Eng. 7733 (2010) 773346

Contribution to:

SPIE Astronomical Telescopes + Instrumentation

Published: Aug 7, 2010

DOI:

10.1117/12.857458

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Abstract: (International Society for Optics and Photonics)

To enable the Hobby-Eberly Telescope Wide Field Upgrade, the University of Texas Center for Electromechanics andMcDonald Observatory are developing a precision tracker system - a 15,000 kg robot to position a 3,100 kg payloadwithin 10 microns of a desired dynamic track. Performance requirements to meet science needs and safety requirementsthat emerged from detailed Failure Modes and Effects Analysis resulted in a system of 14 precision controlled actuatorsand 100 additional analog and digital devices (primarily sensors and safety limit switches). This level of systemcomplexity and emphasis on fail-safe operation is typical of large modern telescopes and numerous industrialapplications. Due to this complexity, demanding accuracy requirements, and stringent safety requirements, a highlyversatile and easily configurable centralized control system that easily links with modeling and simulation tools duringthe hardware and software design process was deemed essential. The Matlab/Simulink simulation environment, coupledwith dSPACE controller hardware, was selected for controls development and realization. The dSPACE real-timeoperating system collects sensor information; motor commands are transmitted over a PROFIBUS network to servoamplifiers and drive motor status is received over the same network. Custom designed position feedback loops,supplemented by feed forward force commands for enhanced performance, and algorithms to accommodate self-lockinggearboxes (for safety), reside in dSPACE. To interface the dSPACE controller directly to absolute Heidenhain sensorswith EnDat 2.2 protocol, a custom communication board was developed. This paper covers details of software andhardware, design choices and analysis, and supporting simulations (primarily Simulink).

Hobby-Eberly
HET
HETDEX
precision motion control
tracking
robotic motion
dSPACE

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