Design, testing, and installation of a high-precision hexapod for the Hobby-Eberly Telescope dark energy experiment (HETDEX)

Zierer, Joseph; Beno, J.H.; Weeks, D.A.; Soukup, Ian; Good, John M.; Booth, John A.; Hill, Gary J.; Rafal, Marc D.

doi:10.1117/12.926394

Cited by 16 publications

(5 citation statements)

References 9 publications

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“…The combination of multiple actuators in each leg can incorporate the advantages of both [112]. Furthermore, different leg designs for this platform approach, using a variety of actuators and featuring different kinematic characteristics [113][114][115][116][117][118][119][120][121], have been proposed, but few have actually been manufactured and tested [122]. Another possible improvement to the Gough-Stewart platform is the use of flexure hinges to reduce backlash and nonlinear friction [123].…”

Section: Pointing Mechanismsmentioning

confidence: 99%

High-Precision Low-Cost Gimballing Platform for Long-Range Railway Obstacle Detection

Assaf

Cornelius

Cadena

et al. 2022

Sensors

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Increasing demand for rail transportation results transportation by rail, resulting in denser and more high-speed usage of the existing railway network, making makes new and more advanced vehicle safety systems necessary. Furthermore, high traveling speeds and the greatlarge weights of trains lead to long braking distances—all of which necessitates Long braking distances, due to high travelling speeds and the massive weight of trains, necessitate a Long-Range Obstacle Detection (LROD) system, capable of detecting humans and other objects more than 1000 m in advance. According to current research, only a few sensor modalities are capable of reaching this far and recording sufficiently accurate enoughdata to distinguish individual objects. The limitation of these sensors, such as a 1D-Light Detection and Ranging (LiDAR), is however a very narrow Field of View (FoV), making it necessary to use ahigh-precision means of orienting to target them at possible areas of interest. To close this research gap, this paper presents a novel approach to detecting railway obstacles by developinga high-precision pointing mechanism, for the use in a future novel railway obstacle detection system In this work such a high-precision pointing mechanism is developed, capable of targeting aiming a 1D-LiDAR at humans or objects at the required distance. This approach addresses To address the challenges of a low target pricelimited budget, restricted access to high-precision machinery and equipment as well as unique requirements of our target application., a novel pointing mechanism has been designed and developed. By combining established elements from 3D printers and Computer Numerical Control (CNC) machines with a double-hinged lever system, simple and cheaplow-cost components are capable of precisely orienting an arbitrary sensor platform. The system’s actual pointing accuracy has been evaluated using a controlled, in-door, long-range experiment. The device was able to demonstrate a precision of 6.179 mdeg, which is at the limit of the measurable precision of the designed experiment.

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Section: Pointing Mechanismsmentioning

confidence: 99%

High-Precision Low-Cost Gimballing Platform for Long-Range Railway Obstacle Detection

Assaf

Cornelius

Cadena

et al. 2022

Sensors

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“…As the six legs are actuated, the two surfaces’ relative position and angle can be controlled in all six DOF. A recent example of the hexapod technology can be seen in the implementation of the hexapod system in telescopes (Yang et al., 2015), specifically the Hobby–Eberly telescope (Wedeking et al., 2010; Zierer et al., 2010, 2012). The thermal morphing hexapod, discussed elsewhere by the authors (Phoenix and Tarazaga, 2017), introduces rotational constraints in conjunction with thermal strain actuation to improve the minimum morphing capability.…”

Section: Introductionmentioning

confidence: 99%

Thermal morphing anisogrid smart space structures: Part 1. Introduction, modeling, and performance of the novel smart structural application

Phoenix

Tarazaga

2017

Journal of Vibration and Control

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To meet the requirements for the next generation of space missions, a paradigm shift is required from current structures that are static, heavy, and stiff to innovative structures that are adaptive, lightweight, versatile, and intelligent. The largest benefit provided by this new structural concept is in the ability to deliver high precision position stability. The conventional high precision structural design uses two decoupled systems to achieve positional stability. First, a high mass structure delivers the effectively infinite stiffness and thermal stability so that no deformations occur under all operational loading conditions. Second, to meet the morphing and on-orbit positional requirements, supplementary mechanisms provide the nano, micro, and macro displacement control required. This paper proposes the use of a novel morphing structure, the thermally actuated anisogrid morphing boom, to meet the design requirements through actively morphing the primary structure in order to adapt to the on-orbit environment and meet both requirements in a consolidated structure. The proposed concept achieves the morphing control through the use of thermal strain to actuate the individual helical members in the anisogrid structure. Properly controlling the temperatures of multiple helical members can introduce six degree of freedom morphing control. This system couples the use of low coefficient of thermal expansion materials with precise thermal control to provide the high precision morphing capability. This concept has the potential to provide substantial mass reductions relative to current methods and meet the high precision displacement requirements of spacecraft systems. This paper will detail the concept itself, demonstrate the modeling procedure, and investigate the design space to quantify the potential of the thermally morphing anisogrid smart structure.

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“…It will be a third generation evolution of the trackers for HET and SALT, and is in essence a precision six-axis stage. The tracker is being developed by the Center for Electro-Mechanics (CEM) at the University of Texas at Austin [18][19][20][21][22][23][24][25][26][27] , with integration at the CEM facility scheduled for Fall 2010.…”

Section: Introduction: Het Wide Field Upgrade and Industrial Replicatmentioning

confidence: 99%

VIRUS: a massively replicated 33k fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

et al. 2010

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The Visible Integral-field Replicable Unit Spectrograph (VIRUS) consists of a baseline build of 150 identical spectrographs (arrayed as 75 units, each with a pair of spectrographs) fed by 33,600 fibers, each 1.5 arcsec diameter, deployed over the 22 arcminute field of the upgraded 10 m Hobby-Eberly Telescope (HET). The goal is to deploy 96 units. VIRUS has a fixed bandpass of 350-550 nm and resolving power R~700. VIRUS is the first example of industrial-scale replication applied to optical astronomy and is capable of spectral surveys of large areas of sky. The method of industrial replication, in which a relatively simple, inexpensive, unit spectrograph is copied in large numbers, offers significant savings of engineering effort, cost, and schedule when compared to traditional instruments.The main motivator for VIRUS is to map the evolution of dark energy for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX ‡ ) using 0.8M Lyman-α emitting galaxies as tracers. The full VIRUS array is due to be deployed in late 2011 and will provide a powerful new facility instrument for the HET, well suited to the survey niche of the telescope. VIRUS and HET will open up wide field surveys of the emission-line universe for the first time. We present the design, cost, and current status of VIRUS as it enters production, and review performance results from the VIRUS prototype. We also present lessons learned from our experience designing for volume production and look forward to the application of the VIRUS concept on future extremely large telescopes (ELTs). * The Hobby -Eberly Telescope is operated by McDonald Observatory on behalf

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Design, testing, and installation of a high-precision hexapod for the Hobby-Eberly Telescope dark energy experiment (HETDEX)

Cited by 16 publications

References 9 publications

High-Precision Low-Cost Gimballing Platform for Long-Range Railway Obstacle Detection

High-Precision Low-Cost Gimballing Platform for Long-Range Railway Obstacle Detection

Thermal morphing anisogrid smart space structures: Part 1. Introduction, modeling, and performance of the novel smart structural application

VIRUS: a massively replicated 33k fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

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