Assembly, Integration & Verification

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Introduction

The Assembly, Integration and Verification (AIV) work package represents one of nine key elements that will make up the SKA1 Telescope. Whereas the other eight elements are tasked with designing key components of the SKA1 Telescope, the AIV element is tasked to perform all necessary planning to integrate these key components into a telescope system that meets the engineering (Level-1) requirements.

The SKA1 Telescope will consist of SKA1-mid, which will be located in South Africa, and SKA1-low, which will be located in Australia. SKA1-mid will consist out of approximately 133 SKA1-mid Dishes, plus a further 64 MeerKAT Precursor Dishes. The AIV work package therefore also includes the planning for integrating the MeerKAT Precursor into the SKA1-mid Telescope. SKA1-low will consist out of 512 SKA1-low Stations, which will include a total of approximately 125,000 individual low-frequency antennas.

The member organisations of the AIV Consortium are SKASA, CSIRO and ASTRON, with SKASA leading the consortium. All three member organisations have significant experience in building radio telescopes, and therefore have a vast amount of integration and verification know-how that is benefiting the AIV work package.

SKA System Pre-CDR

During November 2017 the SKA Office conducted a System Pre-CDR (Critical Design Review) with the objectives to:

  • Re-focus the attention to the system
  • Prepare feedback for consortia and inform their Element
  • Inform the construction planning
  • Measure the progress on System CDR preparation (system readiness level).

The AIV Consortium provided the following documents for the System Pre-CDR:

  • Roll-Out Plans for SKA1-low and SKA1-mid (Revision 5A)
  • Integration & Verification Plans for SKA1-low and SKA1-mid (Revision 1)
  • Verification Requirements (Revision 2)
  • Product Hand-Over Process
  • MeerKAT Integration Plan and MeerKAT ICDs
  • System Integration Test Facility (co-authored with INFRA-AU and INFRA-SA)
  • AIV Safety Management Plan
  • EMC Control Plan for AIV

This set of documents is a comprehensive encapsulation of the AIV Consortium’s work during pre-construction. It includes large and detailed documents that have been developed in close consultation with subject matter experts from other consortia, and documents which are used by the SKA Office to assist with their overall construction planning.

Updates to the Roll-Out Plans

The Roll-Out Plans (currently at draft Revision 5A) have had a significant make-over and include the following updates:

  • Inclusion of actions from the Construction Schedule workshop that the SKA Office held in October 2017
  • OAR comments received from the SKA Office on Revision 5
  • Description of the SAFe agile framework for developing and rolling-out software
  • Configuration roll-out of Dishes/Stations
  • Functionality provided by TM, SDP, CSP and SaDT
  • Functional allocation to roll-out milestones
  • Deployment Baseline
  • Refined definition of “Array Releases”

The configuration roll-out identifies the Dishes/Stations that are included in each of the four Array Assemblies. For example, Figure1 shows the array configuration of Array Assembly 1 for SKA1-mid and SKA1-low.

ECP-170050 has been submitted to bring the Roll-Out Plans to Revision 6.

Figure 1: Array Assembly 1 configuration for SKA1-mid and SKA1-low.

Integration & Verification Plans

Revision 1 of the Integration & Verification Plans for both SKA1-mid and SKA1-low have been released. These documents describe the integration and verification activities for the two telescopes in detail. They cover:

  • The conduct of the AIV Contractors, roles and responsibilities, strategies, tools and processes for Integration and Verification.
  • The identification of individual test cases that will be performed on each Array Assembly.

It is this second facet, the identification of individual test cases, along with the hierarchical nature of AIV planning, which provides an excellent basis for bottom-up analysis of AIV activities:

  • Inputs and dependencies for commencement of each test have been defined.
  • Resources have been assigned to each test case to develop an overall picture for AIV resourcing.
  • Time has been assigned to each test case to develop an overall AIV schedule (Gantt chart).

Figure 2 shows an example schematic from the SKA1-low Integration and Verification Plan showing the relationships between low-level test cases for Array Assembly 1. As can be seen, the dependencies are clearly identified. By assigning a duration to each test case a Gantt chart can be created for this section.

Since the AIV Consortium is looking at system-level integration and verification activities, the schedule derived from the Integration and Verification Plan must be reconciled with the overall SKA Project Construction Schedule. Working closely with the Project Management group within the SKA Office and with project managers from other consortia, the AIV Consortium has been able to discuss and negotiate product delivery schedules that align closely with the planned integration.

Figure 2: Example schematic from the SKA1-low Integration and Verification Plan.

Challenges

Experience with other radio telescopes has consistently shown that the roll-out activities and AIV work scope is often under-estimated, even at component level, and often causes delays in deployment, due to re-engineering and retrofitting of components. This may significantly increase the total cost of the system.

Many issues that are discovered during “downstream” integration and verification are the result of “upstream” neglect. Early in the project, during the design stage, science requirements need to be accurately translated to Element-level requirements, and interfaces between products need to be accurately defined.


Report provided by the AIV consortium