The Giant Magellan Telescope (GMT) is a next-generation ground-based segmented telescope. In the last few years, significant progress has been made by the GMT team and partners to design a natural guide-star wavefront control strategy that can reliably correct wavefront error, including the discrete piston aberration between segment gaps. After an extensive set of simulations and external reviews, the team proposed a design of a Pyramidal Wavefront Sensor (PWFS) combined with a Holographic Dispersed Fringe Sensor (HDFS) and started building a prototype for integrating a GMT simulator (High Contrast AO Testbed) with a PWFS and an HDFS. The prototype was developed in collaboration with the University of Arizona, INAF-Arcetri, and the GMT observatory. The software development of the adaptive optics controllers and the interfaces between all testbed components were done using the GMT software frameworks, as they will be implemented for the final observatory software. The GMT framework is model-based, and the software component interfaces are defined using a domain-specific language (DSL). In this paper, we show how the design of the testbed software fits within GMT's component-based architecture and what each partner was responsible for delivering. We discuss the challenge of a multidisciplinary team from multiple institutions in different time zones working together on the same software, describe how the software architecture and development process helped to ensure seamless integration and highlight other accomplishments and lessons learned.
KEYWORDS: Software development, Control systems, Design, Software engineering, Observatories, Telescopes, Industry, Project management, Control systems design, Control software
The Giant Magellan Telescope (GMT) Software and Controls (SWC) team is responsible for designing, implementing, and maintaining the GMT Observatory Control System (OCS). GMT software modules are developed either in-house, or in collaboration with GMT partner institutions, following an Agile software development process. However, these software industry best-practices require significant tailoring to integrate well with other Engineering disciplines on a large, complex project such as GMT. In this paper we explore the various challenges in managing software development and how we are tackling them at GMT. Key areas include building the right team, handling programmatic challenges, streamlining development processes and engaging with customers and stakeholders. We’ve learned that people are at the heart of what we do, and the health of the team directly affects our ability to deliver high quality software on time and within budget. Also, managing limited resources is a common theme, requiring many different solutions in different domains. We have found the most effective to be a combination of process-optimization, resource-loaded scheduling, agile development, drastic overhead reduction and regular review of top priorities to help the team focus on what is important. Lastly, active engagement and efficient communication with customers and other stakeholders from the very beginning, help to set clear expectations and sets the team up for success. The team has made tremendous progress in the last few years in these areas and will continue to do so in the future due to a commitment to continuous improvement.
The Giant Magellan Telescope (GMT) is a complex observatory with thirty major subsystems, many low-level subsystems, components, external contracts, and interfaces. Almost all subsystems require software and controls to operate. An important goal for GMT is to have software and control subsystems that are easy to develop, test, integrate, operate, and maintain. To provide consistency across all controlled subsystems, a set of standards and a reference architecture are provided. Software components are specified using a Domain Specific Language (DSL), which enables code-generation in several languages and automatic validation of architectural conformance and interfaces. Some of the main observatory control subsystems have already been modeled using this approach, and initial implementations are currently being tested. The most advanced control subsystem is the primary mirror Device Control System (M1 DCS), which is currently under testing before the integration of the optical mirror in the test cell. This paper describes the status of the GMT control system, the main lessons learned, and the future steps in the development of the GMT control system.
Large aperture telescopes require active control to maintain focus, collimation, and correct figure errors in the Primary Mirror (M1) due to gravity and thermal deformations. The Giant Magellan Telescope M1 active optics and thermal control systems called the M1 Subsystem (M1S) consists of the hardware and software that controls the shape, position, and thermal state of each mirror segment. A full-scale off-axis M1S prototype called the Test Cell is being fabricated and tested. The primary objective of the Test Cell is to mitigate risk by verifying that the mirror figure and position can be controlled within the image quality error budget and that the thermal control system vibration is within its system level allocation. The M1S components for the active optics support system have been fabricated, assembled, tested at the component level, and integrated into the Test Cell. The team completed the Test Readiness Review and started system level testing with the M1 Device Control Software. Lessons learned throughout the component and integrated system testing of the Test Cell will be incorporated into the M1S design for the production phase. This paper will summarize the progress of the Test Cell and results presented at the Test Readiness Review.
The Primary Mirror Device Control System (M1 DCS) is one of the many Device Control Systems (DCS) included in the Giant Magellan Telescope (GMT) control system and is responsible for the overall control and operation of the GMT primary mirror segments. The primary mirror is composed of seven 8.4m diameter segments, six off-axis and one in the center. The active support system of each segment comprises 170 support actuators for the off-axis segments and 154 actuators for the center segment to control the mirror figure, and 6 hardpoints to control the six degrees of freedom of rigid body motion. The software design follows a component model-based architecture, implemented using the GMT core software frameworks. Software components of the M1 DCS are specified using a custom Domain Specific Language (DSL) and inherit all key features of the core components such as communication ports, default behaviors, telemetry, logs, alarms, faults, state machines and engineering user-interface without the need of a separate implementation. The communication between the real time software and the controlled devices is implemented by an EtherCAT Fieldbus in a ring topology. This master-slave standard protocol enables the control system to reach 100 Hz closed loop rate for active support control. This paper describes the software of the M1 DCS, the tests performed with different software and hardware simulators, and the strategy to ensure software readiness with the final optical mirror.
The Observatory Control System (OCS) for the Giant Magellan Telescope (GMT) includes all the software and hardware components necessary to control and monitor the GMT optical and electromechanical subsystems and to safely and efficiently operate the GMT observatory. The OCS architecture follows both a component-based and a model-based approaches. Software components are specified using a Domain Specific Language (DSL) which enables codegeneration in several languages and automatic validation of architectural conformance and interfaces. This paper describes the agile development process to generate the final software components from the specifications and the status of the whole development effort.
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