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CINEMA System Engineering

CINEMA System Engineering. Dave Curtis. System Engineering Tasks. Requirements Flowdown Identify top-level science and programmatic requirements Flow those requirements down to subsystems Involves some system-level design Verify by analysis and/or test that each requirement is met

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CINEMA System Engineering

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  1. CINEMA System Engineering Dave Curtis CINEMA 2009-10-19 -23

  2. System Engineering Tasks • Requirements Flowdown • Identify top-level science and programmatic requirements • Flow those requirements down to subsystems • Involves some system-level design • Verify by analysis and/or test that each requirement is met • Interface Control, Specifications • Document and track interfaces between subsystems • System Design • Top-level design of how the subsystems work together • Resource Allocation and Tracking • Mass, Power, Link Margin, Pointing, etc. • Money, schedule, manpower resources typically tracked by Project Manager • Technical Coordination and Evaluation • Coordinate the various technical disciplines and subsystem leads to ensure that requirements are being met • Perform technical reviews with independent reviewers to identify any issues • Reliability Engineering and Risk Management • Identify potential technical risks and failure modes and mitigate where possible • System Integration and Test Coordination • Ensure adequate testing to verify all requirements CINEMA 2009-10-19 -23

  3. Requirements • Top level science and programmatic requirements identified in the CINEMA NSF AO and Proposal • Requirements have been extracted into a document and flowed down to the subsystem • ftp://apollo.ssl.berkeley.edu/pub/cinema/2.%20Systems/CINEMA_Requirements.xls • Flowdown depends on system design, which has evolved a bit since the proposal based on design trade studies • Subsystem allocations still in work • Some requirements cannot be nailed down until we have a launch selected • Orbit, Launch loads, etc.; nominal values assumed for now • Requirements organized as follows: • Level 1 Science, Programmatic, and Mission Assurance • Level 2 Subsystems (STEIN, MAGIC, ACS, Telecom, etc) • Level 3 Components (MAGIC Boom, Torque Coils, etc) • Documented requirements provides an agreed upon baseline for the system and subsystem engineers to design and test to, along with a rationale to remind us what we are losing if we cannot meet the requirements • The System Engineer controls the requirements document. CINEMA 2009-10-19 -23

  4. Sample Requirements CINEMA 2009-10-19 -23

  5. Verification • Each requirement must be verified during system testing • Verify early at subsystem/component level where possible • Verify again at the full system level • Verify environmental requirements • Survive launch loads • Operate in vacuum and over temperature • Some requirement verified by analysis, but test is preferred • Ready to launch when all requirement verified • System Engineer tracks verification of requirements CINEMA 2009-10-19 -23

  6. Interface Control Documents • An Interface Control Document (ICD) describes how one subsystem or component interacts with another or with the system as a whole • It augments the requirements document with detailed information about how the interaction between subsystems takes place such that an engineer can design his subsystem. • It includes things like mass and power, interface voltages, currents, signals, timing diagrams, pinouts, etc. • The System Engineer, together with the subsystem engineer, develops the ICD for the subsystem • MAGIC ICD first draft provided by IC. Others to follow as needed CINEMA 2009-10-19 -23

  7. Specifications • Specifications describe the implementation of a component or subsystem • Includes details of how the item works, User information, handling details, etc. • May take the place of an ICD in some cases • Commercial equipment typically includes a specification or users manual • Specifications provide a way of documenting the design as it progresses • Important due to the transient nature of the students who are doing much of the CINEMA development • Specifications are not formally controlled documents; they are expected to evolve with the design and include by reference the schematics, listings, and other low level design information • All controlled documentation available on the CINEMA Web page • ftp://apollo.ssl.berkeley.edu/pub/cinema • All working documentation on the CINEMA Wiki page • http://wiki-new.ssl.berkeley.edu/index.php/Cinema • Password controlled. CINEMA 2009-10-19 -23

  8. System Design • Current top-level design shown in following slides • Design continues to evolve • Design to meet requirements • Science, Technical, and Programmatic • Details of subsystem designs in later talks CINEMA 2009-10-19 -23

  9. Electrical Block Diagram CINEMA 2009-10-19 -23

  10. Mechanical Configuration CINEMA 2009-10-19 -23

  11. Ground System CINEMA 2009-10-19 -23

  12. Operations • Launched powered-off • power-up on deployment from P-Pod • Power up into Safe mode • Instrument and ACS Off • Transceiver powered on, listening • Contact Ground • Set-up time-tagged contact windows so transceiver can be powered off between passes, freeing up power for ACS • MAG Boom Deploy • Determines major axis for stable spin • Deploys magnetometer for ACS • MAG Cal • Use torque rods to determine MAG orientation • ACS Acquisition Mode • Detumble, Spin up, Sun-normal spinning • Precession Mode • Reorient to Ecliptic Normal Spin (requires ground interaction) • Science Mode • Power off ACS, Power up instruments • Return to ACS Mode • Periodic drift correction • Return to Safe Mode • In the event of problems (low power, no ground contact, system reset) • Power up transceiver, wait to be contacted. CINEMA 2009-10-19 -23

  13. Resource Budgets • The following budgets are based on the proposal configuration • Design trades continue to refine the configuration CINEMA 2009-10-19 -23

  14. Mass CINEMA 2009-10-19 -23

  15. Power Generation CINEMA 2009-10-19 -23

  16. Battery CINEMA 2009-10-19 -23

  17. Power Usage Telecom Power CINEMA 2009-10-19 -23

  18. Telecom • Assumes 1 pass/day for command / housekeeping via MHX2400 transceiver • Remaining passes for Science recorder download with S-band transmitter CINEMA 2009-10-19 -23

  19. Reliability • Good design practices, workmanship standards, and high quality parts are key to reliable systems • But are limited by the reality of limited cost and schedule • On such a severely cost constrained mission as CINEMA, reliability is obtained by primarily through testing • Identifies design flaws, poor quality parts, bad workmanship • Test early, test often • Include margin testing (voltage, temperature, frequency, etc) • Include ‘test-as-you-fly’ CINEMA 2009-10-19 -23

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