KEYWORDS: Spectrographs, Astronomical imaging, Optical fibers, Data modeling, Detection and tracking algorithms, Telescopes, Signal processing, Signal generators, Kinematics, Chemical elements
Astrobot swarms are used to capture astronomical signals to generate the map of the observable universe for the purpose of dark energy studies. The convergence of each swarm in the course of its coordination has to surpass a particular threshold to yield a satisfactory map. The current coordination methods do not always reach desired convergence rates. Moreover, these methods are so complicated that one cannot formally verify their results without resource-demanding simulations. Thus we use support vector machines to train a model that can predict the convergence of a swarm based on the data of previous coordination of that swarm. Given a fixed parity, i.e., the rotation direction of the outer arm of an astrobot, corresponding to a swarm, our algorithm reaches a better predictive performance compared to the state of the art. Additionally, we revise our algorithm to solve a more generalized convergence prediction problem according to which the parities of astrobots may differ. We present the prediction results of a generalized scenario, associated with a 487-astrobot swarm, which are interestingly efficient and collision free given the excessive complexity of this scenario compared to the constrained one.
The Sloan Digital Sky Survey V (SDSS-V) is an all-sky spectroscopic survey of > 6 million objects, designed to decode the history of the Milky Way, reveal the inner workings of stars, investigate the origin of solar systems, and track the growth of supermassive black holes across the Universe.1 This paper describes the design of the theta/phi fiber positioner robots that are being produced to be integrated in the Focal Plane System (FPS) of the SDSS-V telescopes. For each installation, 500 robots are being manufactured, more than 800 units have already been received from the manufacturer and validated. Mechanical, electronic and firmware designs are presented in the current paper in detail. We will expose the different iterations of the prototypes that were developed, built and tested and ultimately allowed to achieve the end version that meets the requested science requirements. The fiber positioner robot is carrying 3 optical fibers integrated into a single snowflake ferrule. Two of the fibers are science fibers connected to two different spectrographs, and the third fiber is used for metrology. The robot is capable of positioning the fibers with a planar accuracy better than 50 microns with a first blind move within its workspace of a diameter of 44.8mm. With a complementary fiber viewing camera (FVC) and the backlighted metrology fiber to perform a few small corrections moves, the positioner can reach a sub 5-micron precision on the fiber position.
The Sloan Digital Sky Survey V (SDSS-V) is an all-sky spectroscopic survey of <6 million objects, designed to decode the history of the Milky Way, reveal the inner workings of stars, investigate the origin of solar systems, and track the growth of supermassive black holes across the Universe. This paper describes the design and construction of two robotic Focal Plane System (FPS) units that will replace the traditional SDSS fiber plug-plate systems at the Sloan and du Pont telescopes for SDSS-V. Each FPS deploys 500 zonal fiber positioners that allow us to reconfigure the fibers onto a new target field within 2-3 minutes of acquisition. Each positioner carries three fibers: two science fibers that feed the BOSS and APOGEE spectrographs and a third back-illuminated metrology fiber is used in conjunction with a telescopemounted Fiber Viewing Camera (FVC) to measure the absolute positions of the fiber heads. The 300 APOGEE fibers are distributed among the 500 positioners to maximize common field coverage. A set of fiber-illuminated fiducials distributed in and around the positioner array establish a fixed reference frame for the FVC system. Finally, six CCD cameras mounted around the periphery of the focal plane provide acquisition, guiding, and focus monitoring functions. The FPS is a key enabling technology of the SDSS-V Milky Way and Black Hole Mapper surveys.
Robotic fiber positioners play a vital role in the generation of massive spectroscopic surveys. The more complete a positioners set is coordinated, the more information its corresponding spectrograph receives during an observation. The complete coordination problem of positioners sets is studied. We first define the local and the global completeness problems and determine their relationship. We then propose an artificial potential field according to which the convergences of a positioner and its neighboring positioners are cooperatively taken into account. We also discover the required condition for a complete coordination. We finally explain how the modifications of some of the parameters of a positioners set may resolve its incompleteness coordination scenarios. We verify our accomplishments using simulations.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.