V. Baldini

Adoption of new software and hardware solutions at the VLT: the ESPRESSO control architecture case

ESPRESSO is a fiber-fed cross-dispersed echelle spectrograph which can be operated with one or up to 4 UT (Unit Telescope) of ESOs Very Large Telescope (VLT). It will be located in the Combined-Coudé Laboratory (CCL) of the VLT and it will be the first permanent instrument using a 16-m equivalent telescope. The ESPRESSO control software and electronics are in charge of the control of all instrument subsystems: the four Coudé Trains (one for each UT), the front-end and the fiber-fed spectrograph itself contained within a vacuum vessel. The spectrograph is installed inside a series of thermal enclosures following an onion-shell principle with increasing temperature stability from outside to inside. The proposed electronics architecture will use the OPC Unified Architecture (OPC UA) as a standard layer to communicate with PLCs (Programmable Logical Controller), replacing the old Instrument Local Control Units (LCUs) for ESO instruments based on VME technology. The instrument control software will be based on the VLT Control Software package and will use the IC0 Field Bus extension for the control of the instrument hardware. In this paper we present the ESPRESSO software architectural design proposed at the Preliminary Design Review as well as the control electronics architecture.

ESPRESSO instrument control software and electronics: commissioning in Paranal

The ESPRESSO (Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations) spectrograph, after the preliminary tests carried out at the Astronomical Observatory of Geneva (Switzerland), has been shipped and re-integrated at the Very Large Telescope (VLT) site in Cerro Paranal (Chile). The instrument control software, designed and developed at INAF–Osservatorio Astronomico di Trieste, had to face several challenges since ESPRESSO is the first instrument placed at the VLT Coud`e Combined Laboratory able to be fed by up to 4 Telescope Units simultaneously (through an incoherent focus), and whose electronics is based on Beckhoff PLCs. Moreover, ESPRESSO requires a careful stabilization of the field image in order to maximize the light flux through the fiber hole, and reach the instrumental radial-velocity precision level of 10 cm/s. These circumstances lead to the development of a few solutions specifically dedicated to ESPRESSO. In this paper we will summarize the features of the ESPRESSO control software, the tests performed during the integration phase in Europe, and discuss the main performances obtained during the commissioning phase and ”first light” observations in Chile

A complete automatization of an educational observatory at INAF-OATs

The Astronomical Observatory of Trieste (OATs), part of the Italian Institute for Astrophysics (INAF), hosts a Celestron C14 telescope, equipped with a robotic Paramount ME equatorial mount, used for public outreach. The telescope is installed inside a dome, recently upgraded with a Beckhoff PLC control system, a SIEMENS inverter for the communication with the motor of the domes roof, and further equipment to allow the complete automatization of the system. A peculiarity of the system is that, when operating, the telescope may exceed the height of the roof: due to this fact the telescope pointing is constrained by the full opening of the roof and, oppositely, the closing of the roof is allowed only when the telescope is in park position. Appropriate sensors are installed to monitor the position of the telescope to properly handle the complete opening or closing of the roof. Several emergency operations are also foreseen, for example in case of bad weather or lost connection with the user. The PLC software has been developed using TwinCAT software. An OPC-UA server is installed in the PLC and allows the communication with a web interface. The web GUI, developed in PHP and Javascript, allows the user to perform the remote operations like switching on all the instrumentations, open the domes roof, park the telescope and view the status of the system. Furthermore through TheSkyX software it is possible to perform the pointing of the telescope and its set up. A dedicated script, interfaced with TheSkyX, have been implemented to perform a complete automated acquisition. An appropriate data storage system is foreseen. All these elements, that cooperate to create a fully remoted controlled system, are presented in this paper.

EELT-HIRES the high resolution spectrograph for the E-ELT: software and hardware solutions for its control

The current E-ELT instrumentation plan foresees a High Resolution Spectrograph conventionally indicated as EELTHIRES whose Phase A study has started in March 2016. Since 2013 however, a preliminary study of a modular E-ELT instrument able to provide high-resolution spectroscopy (R~100,000) in a wide wavelength range (0.37-2.5 μm) has been already conducted by an international consortium (termed “HIRES initiative”). Taking into account the requirements inferred from this preliminary work in terms of both high-level operations as well as low-level control, we will present in this paper possible solutions for HIRES hardware and software architecture. The validity of the proposed architectural and hardware choices will be eventually discussed based also on the experience gained on a real-working instrument, ESPRESSO, the next generation high-stability spectrograph for the VLT and to certain extent the precursor of HIRES.

The design of the local monitor and control system of SKA dishes

The Square Kilometer Array (SKA) project aims at building the world’s largest radio observatory to observe the sky with unprecedented sensitivity and collecting area. In the first phase of the project (SKA1), an array of dishes, SKA1-MID, will be built in South Africa. It will consist of 133 15m-dishes, which will include the MeerKAT array, for the 0.350-20 GHz frequency band observations. Each antenna will be provided with a local monitor and control system (LMC), enabling operations both to the Telescope Manager remote system, and to the engineers and maintenance staff; it provides different environment for the telescope control (positioning, pointing, observational bands), metadata collection for monitoring and database storaging, operational modes and functional states management for all the telescope capabilities. In this paper we present the LMC software architecture designed for the detailed design phase (DD), where we describe functional and physical interfaces with monitored and controlled sub-elements, and highlight the data flow between each LMC modules and its sub-element controllers from one side, and Telescope Manager on the other side. We also describe the complete Product Breakdown Structure (PBS) created in order to optimize resources allocation in terms of calculus and memory, able to perform required task for each element according to the proper requirements. Among them, time response and system reliability are the most important, considering the complexity of SKA dish network and its isolated placement. Performances obtained by software implementation using TANGO framework will be discussed, matching them with technical requirements derived by SKA science drivers.

The technical CCDs in ESPRESSO: usage, performances, and network requirements

The Echelle Spectrograph for Rocky Exoplanets and Stable Spectral Observations (ESPRESSO) requires active-loop stabilization of the light path from the telescope to the spectrograph, in order to achieve its centimeter-per- second precision goal. This task is accomplished by moving the mirrors placed along the light path by means of piezoelectric actuators. Two cameras are used to acquire the field and pupil images, and the required corrections are dynamically calculated and applied to the piezos. In this paper we will discuss the camera usage, performance and network bandwidth requirements for the ESPRESSO scientific operations.

Integration of the instrument control electronics for the ESPRESSO spectrograph at ESO-VLT

ESPRESSO, the Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations of the ESO - Very Large Telescope site, is now in its integration phase. The large number of functions of this complex instrument are fully controlled by a Beckhoff PLC based control electronics architecture. Four small and one large cabinets host the main electronic parts to control all the sensors, motorized stages and other analogue and digital functions of ESPRESSO. The Instrument Control Electronics (ICE) is built following the latest ESO standards and requirements. Two main PLC CPUs are used and are programmed through the TwinCAT Beckhoff dedicated software. The assembly, integration and verification phase of ESPRESSO, due to its distributed nature and different geographical locations of the consortium partners, is quite challenging. After the preliminary assembling and test of the electronic components at the Astronomical Observatory of Trieste and the test of some electronics and software parts at ESO (Garching), the complete system for the control of the four Front End Unit (FEU) arms of ESPRESSO has been fully assembled and tested in Merate (Italy) at the beginning of 2016. After these first tests, the system will be located at the Geneva Observatory (Switzerland) until the Preliminary Acceptance Europe (PAE) and finally shipped to Chile for the commissioning. This paper describes the integration strategy of the ICE workpackage of ESPRESSO, the hardware and software tests that have been performed, with an overall view of the experience gained during these project’s phases.

ESPRESSO instrument control electronics: a PLC based distributed layout for a second generation instrument at ESO VLT

ESPRESSO is an ultra-stable fiber-fed spectrograph designed to combine incoherently the light coming from up to 4 Unit Telescopes of the ESO VLT. From the Nasmyth focus of each telescope the light, through an optical path, is fed by the Coudé Train subsystems to the Front End Unit placed in the Combined Coudé Laboratory. The Front End is composed by one arm for each telescope and its task is to convey the incoming light, after a calibration process, into the spectrograph fibers. To perform these operations a large number of functions are foreseen, like motorized stages, lamps, digital and analog sensors that, coupled with dedicated Technical CCDs (two per arms), allow to stabilize the incoming beam up to the level needed to exploit the ESPRESSO scientific requirements. The Instrument Control Electronics goal is to properly control all the functions in the Combined Coudé Laboratory and the spectrograph itself. It is fully based on a distributed PLC architecture, abandoning in this way the VME-based technology previously adopted for the ESO VLT instruments. In this paper we will describe the ESPRESSO Instrument Control Electronics architecture, focusing on the distributed layout and its interfaces with the other ESPRESSO subsystems.

The upgrade of an educational observatory control system with a PLC-based architecture

A Celestron C14 telescope equipped with a robotic Paramount ME equatorial mount is being used for public outreach at the Basovizza site of the INAF-Astronomical Observatory of Trieste. Although the telescope could be fully remotely controlled, the control of the instrumentations and the movement of the main motor of the dome requires the physical presence of an operator. To overcome this limitation the existing control system has been upgraded using a Beckhoff PLC to allow the remote control of the whole instrumentation, including the management of the newly installed weather sensor and the access to the telescope area. Exploiting the decentralization features typical of a PLC based solution, the PLC modules are placed in two different racks, according to the function to be controlled. A web interface is used for the communication between the user and the instrumentation. The architecture of this control system will be presented in detail in this paper.