Spacecraft Orbit State V&V

Topics related to QA and V&V of GMAT features

Spacecraft Orbit State V&V

Postby jjkparker » Mon Apr 09, 2012 9:27 pm

Overview
There are a lot of tests for this feature for singularities with different orbit types (parabolic, hyperbolic, retrograde). The two main areas of work are reevaluating the limits around those singularities and improving the interaction in the GUI between the state type and the coordinate system.

References

Requirements
  • FRR-1.1.0 states: "The system shall allow the user to defined the spacecraft state, in any inertial coordinate system with a celestial body (as defined in FRR-16), using the following state representations". The "with a celestial body" part is confusing. Is it supposed to be "with the origin at a celestial body"?
  • FRR-1.1.0 and FRR-1.2.0 are inconsistent: "spacecraft state" in one, "orbital state" in the other.
  • FRR-1.1.0 is mislabeled "FFR-1.1.0"
  • FRR-1.3 wording: "...provided the coordinate system conditions requirements FRR-1.1..."

Known issues
1. GMT-1771: Spacecraft allows conversion for singular conic section.
Recommendation: Fix this along with Unreported Issue #5 (Priority: P1, Fix by: 2012a)

2. GMT-2191: Near Zero True Anomaly (and others) gets set to identically zero
Recommendation: Fix this along with Unreported Issue #5 (Priority: P1, Fix by: 2012a)

3. GMT-2454: Conversion errors for AOP and TA
Recommendation: Potentially not a bug; investigate this along with Unreported Issue #5 (Priority: P1, Fix by: 2012a)

4. GMT-2459: State conversion errors for a certain non-default orbit
Recommendation: Possible truth data error, Joel will fix (Priority: P1, Fix by: 2013a)

5. GMT-2461: Major errors in state when changing specific coordinate systems.
Recommendation: Possible truth data error, Joel will fix (Priority: P1, Fix by: 2013a)

6. GMT-2462: Conversion error when performing modulo conversion
Recommendation: Fix this along with Unreported Issue #5 (Priority: P1, Fix by: 2012a)

7. GMT-2501: Setting Partial State in Assignment Mode Changes Independent State Values
Recommendation: Fix (Priority: P1, Fix by: 2012a)

8. GMT-2511: Spacecraft Orbit Validation Failures
Recommendation: Appears to be fixed. Confirm and close. (Priority: P1, Fix by: 2012a)

Failing tests
  • CoupledInputTests
  • Spacecraft_Validation_EquinoctialQ_7
  • Spacecraft_Validation_EquinoctialP_7

Unreported issues
1. When an inertial-only state type is selected and a user-created non-inertial coordinate system is created, the Spacecraft panel lets you select the non-inertial coordinate system. Then switching state types causes instability.
Recommendation: Priority: P1, Fix by: 2013a

2. User-created coordinate systems created while the Spacecraft panel is showing disappear from Coordinate System list when an incompatible state type is selected, but then don't reappear until the panel is closed and reopened.
Recommendation: Priority: P1, Fix by: 2013a

3. When a non-inertial coordinate system is created, then the Spacecraft panel is opened, the panel lets you display inertial-only state types in the non-inertial system.
Recommendation: Priority: P1, Fix by: 2013a

4. Other GUI issues with coupling between State Type and Coordinate System.
Recommendation: Investigate more and check in bugs as P1-2013a

5. Investigate GMAT's limits when the state is nearly singular and propose any necessary changes.
Recommendation: Joel will investigate (Priority: P1, Fix by: 2012a)
Joel J. K. Parker
Flight dynamics engineer, GMAT team
http://gmatcentral.org
jjkparker
 
Posts: 617
Joined: Thu Jan 07, 2010 9:48 pm
Location: NASA Goddard Space Flight Center, Greenbelt, MD

Re: Spacecraft Orbit State V&V

Postby dev-wcs » Tue May 01, 2012 7:37 pm

Reviewed:

• Requirements - look OK
• Draft Feature Specs - followed link to new location; added comments
• Draft Field Spec - incomplete
• Old reference page - Are these values still correct? Equinoctial not included.
• Common tasks - looks OK

Known Issues:

• 1771 - was just moved to R2013a P2
• 2191 - was just moved to R2013a P1
• 2454 - needs tolerance decision

Will review code tomorrow
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dev-wcs
 
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Re: Spacecraft Orbit State V&V

Postby shughes » Mon May 14, 2012 8:11 pm

More unreported issues:

It appears if an invalid value is entered in the GUI, say ECC = 1, that after throwing an error message, the converter algorithm is still called because I get a second error message that says "GMAT does not support parabolic orbits".

When equinoctial conversion is near 180 degree inclination singularity, conversions have large numeric noise/error.
shughes
 
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