Functional Requirements Status and Plans
Christopher Neyman
W. M. Keck Observatory
Viswa Velur
California Institute of Technology
Keck NGAO Team Meeting #10
September 17, 2007
012 Robison Laboratory
Outline
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How to find the FRD drafts and other materials
Status of AO and laser FRD draft 0.2
Thoughts on long term requirements management
Discussion
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FRD: How to get there (Twiki)
Use this Link
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FRD: one stop “shopping” (Twiki)
Links to current supporting documents
http://www.oir.caltech.edu/twiki_oir/bin/view.cgi/Keck/NGAO/FunctionalRequirements
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FRD: AO and laser drafts v0.2 (Twiki)
closer to v0.2
closer to v0.2
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http://www.oir.caltech.edu/twiki_oir/bin/view.cgi/Keck/NGAO/FunctionalRequirements
FRD: AO section status v0.2
• Required functionality well documented
• Specification need work, values are still TBD
• Traceability needed
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Who was the source of the requirement?
Revision history
Approval status (draft, final, approved, pending, dropped)
Science → system → function,
Numbering scheme: not consistent between documents
(ScRD,SRD,FRD)
• Rational needed
• Why this requirement is needed
• What reference material supports it
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FRD: Laser Guide Star Facility section
status v0.2
• Laser status
– 27 pages of requirements
– Tried to cover the bits that make NGAO system different from K1/ K2
LGS.
– Have received some inputs on the draft. Need more at this point.
• Required functionality well documented
• Specification need work, still some TBDs
– Needs some work in integrating and cross referencing tables wrt the
main FRD.
– Other specific requirements that spring up during this phase will need to
be added.
• Traceability
• Rational needed
– The need/source of most requirements is indicated in brackets with
italicized text.
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Total NGAO requirements will be large
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Still have FRD sections for instruments and science operations tools
Preliminary design and detailed design
Draft subcontracts from main NGAO requirements
Other systems that are smaller in scope
– MOSFIRE: ~700 requirements
– NGWFC: 342 requirements
– MAGIQ: ~300 requirements
• NGAO detailed requirements estimate
AO = 8*NGWFC ~ 2700
LASER= 4*NGWFC ~ 1370
Ops. tools=4*NGWFC= ~1370
Instruments = 3*MOSFIRE ~ 2100
TOTAL ~ 7500 requirements
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Will we ever need to know the following?
• The origin of a requirement (backwards trace)
• Affects of a requirements change, such as the impact on a
design, interfaces, and/or subsystems (forward trace)
• The most important requirements, especially if resources
limited
• The highest risk requirements
• How a requirement will be tested (inspection, analysis,
demonstration, test) (compliance matrix)
• A requirement has been satisfied (compliance matrix)
• Requirements that are unaddressed or unassigned
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Requirements need supporting information
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The source of the requirement (who nominated it)
A unique identifying number for it
The rationale for the requirement (why is the requirement needed?)
Change history (how has the statement of the requirement changed
over the system life?)
• Traceability (of each requirement to its source)
• Status (draft, final, approved, pending approval, disapproved)
• Assigned to (which subsystem or component of the system)
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Requirements need supporting information
• Also useful to capture the following:
– Its priority (on a scale of one to three)
– Its relative cost to implement (low, medium, high)
– Its relative difficulty to implement (low, medium, high)
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Thoughts on requirements management
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To automate or not to automate
• Group could consider automated tools
– Software industry
– Database used at Keck NGWFC and MAGIQ
– LLNL, JPL, TMT (What do they use?)
• Better suited to bigger project
• Choice of process or knowledgeable scientist, engineer
• Resources limited
Thanks for listening: discussion or questions?
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