&lt;title&gt;Early performance and present status of the Hobby-Eberly Telescope&lt;/title&gt;

Ramsey, Lawrence W.; Adams, Mark T.; Barnes, Thomas G.; Booth, John A.; Cornell, Mark E.; Fowler, James R.; Gaffney, Niall; Glaspey, J. W.; Good, John M.; Hill, Gary J.; Kelton, P. W.; Krabbendam, Victor L.; Long, L.; MacQueen, Phillip J.; Ray, Frank B.; Ricklefs, R. L.; Sage, Jeremy; Sebring, Thomas A.; Spiesman, W. J.; Steiner, Marc

doi:10.1117/12.319287

Cited by 230 publications

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“…Fowlkes in the Davis Mountain Range in West Texas. A joint venture with The Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen, the HET has been conducting science operations since October, 1999 1 . The HET support structure and primary mirror sits at a fixed zenith angle of 35º and can move in azimuth to access approximately 70% of the visible sky.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2010

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To enable the Hobby-Eberly Telescope Wide Field Upgrade, the University of Texas Center for Electromechanics and McDonald Observatory are developing a precision tracker system -a 15,000 kg robot to position a 3,100 kg payload within 10 microns of a desired dynamic track. Performance requirements to meet science needs and safety requirements that emerged from detailed Failure Modes and Effects Analysis resulted in a system of 14 precision controlled actuators and 100 additional analog and digital devices (primarily sensors and safety limit switches). This level of system complexity and emphasis on fail-safe operation is typical of large modern telescopes and numerous industrial applications. Due to this complexity, demanding accuracy requirements, and stringent safety requirements, a highly versatile and easily configurable centralized control system that easily links with modeling and simulation tools during the hardware and software design process was deemed essential. The Matlab/Simulink simulation environment, coupled with dSPACE controller hardware, was selected for controls development and realization. The dSPACE real-time operating system collects sensor information; motor commands are transmitted over a PROFIBUS network to servo amplifiers 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-locking gearboxes (for safety), reside in dSPACE. To interface the dSPACE controller directly to absolute Heidenhain sensors with EnDat 2.2 protocol, a custom communication board was developed. This paper covers details of software and hardware, design choices and analysis, and supporting simulations (primarily Simulink).

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Section: Introductionmentioning

confidence: 99%

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

et al. 2010

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“…The Hobby-Eberly Telescope (HET) in Figure 1, located in the Davis Mountain Range at The University of Texas' McDonald Observatory, has been conducting science operations since October, 1999 1 . The HET is a modified Arecibostyle telescope, with a 9.2-meter segmented primary mirror tilted at a fixed zenith angle of 35º 2 .…”

Section: Introductionmentioning

confidence: 99%

The development of high-precision hexapod actuators for the Hobby-Eberly Telescope wide field upgrade

et al. 2010

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Hexapods are finding increased use in telescope applications for positioning large payloads. Engineers from The University of Texas at Austin have been working with engineers from ADS International to develop large, high force, highly precise and controllable hexapod actuators for use on the Wide Field Upgrade (WFU) as part of the Hobby Eberly Telescope Dark Energy Experiment (HETDEX) ‡ . These actuators are installed in a hexapod arrangement, supporting the 3000+ kg instrument payload which includes the Wide Field Corrector (WFC), support structure, and other optical/electronic components. In addition to force capability, the actuators need to meet the tracking speed (pointing) requirements for accuracy and the slewing speed (rewind) requirements, allowing as many observations in one night as possible. The hexapod actuator stroke (retraction and extension) was very closely monitored during the design phase to make sure all of the science requirements could be met, while minimizing the risk of damaging the WFC optical hardware in the unlikely event of a hexapod actuator or controller failure. This paper discusses the design trade-offs between stiffness, safety, back-drivability, accuracy, and leading to selection of the motor, high ratio worm gear, roller screw, coupling, end mounts, and other key components.

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“…Fowlkes in the Davis Mountain Range in West Texas and has been conducting science operations since October, 1999 1 . The HET support structure and primary mirror sits at a fixed zenith angle of 35º and can move in azimuth to access approximately 70% of the visible sky.…”

Section: Introductionmentioning

confidence: 99%

Design and development of a high-precision, high-payload telescope dual-drive system

et al. 2010

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A high precision, dual drive system has been designed and developed for the Wide Field Upgrade to the Hobby-Eberly Telescope * at McDonald Observatory in support of the Hobby-Eberly Telescope Dark Energy Experiment ‡ . Analysis, design and controls details will be of interest to designers of large scale, high precision robotic motion devices. The drive system positions the 19,000 kg star tracker to a precision of less than 5 microns along its 4-meter travel. While positioning requirements remain essentially equal to the existing HET, tracker mass increases by a factor greater than 5. The 10.5-meter long tracker is driven at each end by planetary roller screws, each having two distinct drive sources dictated by the desired operation: one slowly rotates the screw when tracking celestial objects and the second rotates the nut for rapid displacements. Key results of the roller screw rotordynamics analysis are presented. A description of the complex bearing arrangement providing required degrees of freedom as well as the impact of a detailed Failure Modes and Effects Analysis addressing necessary safety systems is also presented. Finite element analysis results demonstrate how mechanical springs increase the telescope's natural frequency response by 22 percent. The critical analysis and resulting design is provided.

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<title>Early performance and present status of the Hobby-Eberly Telescope</title>

Cited by 230 publications

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

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

The development of high-precision hexapod actuators for the Hobby-Eberly Telescope wide field upgrade

Design and development of a high-precision, high-payload telescope dual-drive system

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