Current status of the Hobby-Eberly Telescope wide-field upgrade

Savage, R. L.; Booth, John A.; Cornell, Mark E.; Good, J. C.; Hill, Gary J.; Lee, Hanshin; MacQueen, Phillip J.; Rafal, Marc D.; Vattiat, Brian L.; Gebhardt, Karl; Beno, J.H.; Zierer, Joseph; Perry, Dewayne E.; Rafferty, Tom; Ramiller, C. L.; Taylor, Charles; Beets, Timothy; Hayes, Richard B.; Heisler, J T; Hinze, Sarah; Soukup, Ian; Jackson, John D.; Mock, Jason R.; Worthington, Michael; Mollison, Nicholas; Molina, Omar Franklin; South, Brian; Wardell, D.; Wedeking, Gregory

doi:10.1117/12.857203

Cited by 14 publications

(23 citation statements)

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“…To begin, the existing HET design places many components, including the hexapod struts and wide field corrector, inside the volume of the bridge structure 1 . This impedes access for routine inspection and maintenance of these critical components as a side-effect; plus adapting this design for the new dimensions required by the WFU would produce a much wider structure, placing more of the bridge outside the WFC central obscuration area (the area where obstructions to incoming light have the least adverse effect).…”

Section: Y-axis Drive System Design Considerationsmentioning

confidence: 99%

“…The Wide Field Upgrade presents a five-fold increase in mass for the Hobby-Eberly Telescope's tracker system, with the total mass of the new tracker approaching 19,000kg. The design of the Hobby-Eberly Telescope places the PFIP at a thirty-five degree angle from horizontal 1 . The PFIP, WFC, hexapod, and associated sub-structure and hardware (collectively referred to as the "payload" within this paper) have historically been positioned along this uphill Y-axis by a single screw-type actuator.…”

Section: Introductionmentioning

confidence: 99%

“…The Hobby Eberly Telescope (HET) (Figure 1) is undergoing a major upgrade in preparation for the HET Dark Energy eXperiment ‡ (HETDEX), as well as to enhance support capabilities for current and future instrumentation 1 . HETDEX entails two major hardware upgrades to the HET: the Wide Field Upgrade (WFU), and the fabrication and installation of 192 spectrometers called VIRUS 2 .…”

Section: Introductionmentioning

confidence: 99%

“…HETDEX entails two major hardware upgrades to the HET: the Wide Field Upgrade (WFU), and the fabrication and installation of 192 spectrometers called VIRUS 2 . The WFU consists of four related engineering projects: 1) Replacing the current spherical aberration corrector with the Wide Field Corrector 3 (WFC), which will increase the HET field of view from 4′ to 22′, 2) replacing the entire tracker system, 3) a new Prime Focus Instrument Package (PFIP), and 4) modifications to the HET facility 1 . Under the tracker portion of the program, improvements are being made to the HET's motion control systems to increase tracker payload capacity and to hasten "reset" speed, allowing more observations per night as required for HETDEX 2 .…”

Section: Introductionmentioning

confidence: 99%

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Design and development of a long-travel positioning actuator and tandem constant force actuator safety system for the Hobby Eberly Telescope wide-field upgrade

et al. 2010

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The Wide Field Upgrade presents a five-fold increase in mass for the Hobby-Eberly Telescope's * tracker system. The design of the Hobby-Eberly Telescope places the Prime Focus Instrument Package (PFIP) at a thirty-five degree angle from horizontal. The PFIP and its associated hardware have historically been positioned along this uphill axis (referred to as the telescope's Y-axis) by a single screw-type actuator. Several factors, including increased payload mass and design for minimal light obscuration, have led to the design of a new and novel configuration for the Y-axis screw-drive as part of the tracker system upgrade. Typical screw-drive designs in this load and travel class (approximately 50 kilonewtons traveling a distance of 4 meters) utilize a stationary screw with the payload translating with the moving nut component. The new configuration employs a stationary nut and translating roller screw affixed to the moving payload, resulting in a unique drive system design. Additionally, a second cable-actuated servo drive (adapted from a system currently in use on the Southern African Large Telescope) will operate in tandem with the screw-drive in order to significantly improve telescope safety through the presence of redundant load-bearing systems. Details of the mechanical design, analysis, and topology of each servo drive system are presented in this paper, along with discussion of the issues such a configuration presents in the areas of controls, operational and failure modes, and positioning accuracy. Findings and results from investigations of alternative telescope safety systems, including deformable crash barriers, are also included.

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Section: Y-axis Drive System Design Considerationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Design and development of a long-travel positioning actuator and tandem constant force actuator safety system for the Hobby Eberly Telescope wide-field upgrade

et al. 2010

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“…The Hobby-Eberly Telescope (HET) is currently undergoing a major redesign effort in preparation for the Dark Energy Experiment 2,3 . The upgrade, referred to as HETDEX, involves replacing the current star tracker 4 along with its drive systems.…”

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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Wind loading analysis and strategy for deflection reduction on HET wide field upgrade

et al. 2010

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Wind loading can be a detrimental source of vibration and deflection for any large terrestrial optical telescope. The Hobby-Eberly Telescope * (HET) in the Davis Mountains of West Texas is undergoing a Wide Field Upgrade (WFU) in support of the Dark Energy Experiment ‡ (HETDEX) that will greatly increase the size of the instrumentation subjected to operating wind speeds of up to 20.1 m/s (45 mph). A non-trivial consideration for this telescope (or others) is to quantify the wind loads and resulting deflections of telescope structures induced under normal operating conditions so that appropriate design changes can be made. A quasi-static computational fluid dynamics (CFD) model was generated using wind speeds collected on-site as inputs to characterize dynamic wind forces on telescope structures under various conditions. The CFD model was refined until predicted wind speed and direction inside the dome agreed with experimental data. The dynamic wind forces were then used in static loading analysis to determine maximum deflections under typical operating conditions. This approach also allows for exploration of operating parameters without impact to the observation schedule of the telescope. With optimum combinations of parameters (i.e. dome orientation, tracker position, and louver deployment), deflections due to current wind conditions can be significantly reduced. Furthermore, the upper limit for operating wind speed could be increased, provided these parameters are monitored closely. This translates into increased image quality and observing time.

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Current status of the Hobby-Eberly Telescope wide-field upgrade

Cited by 14 publications

References 0 publications

Design and development of a long-travel positioning actuator and tandem constant force actuator safety system for the Hobby Eberly Telescope wide-field upgrade

Design and development of a long-travel positioning actuator and tandem constant force actuator safety system for the Hobby Eberly Telescope wide-field upgrade

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

Wind loading analysis and strategy for deflection reduction on HET wide field upgrade

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