ION CubeSat Dependency Analysis

Primary Researchers: Leon Arber

The ION CubeSat is an amatuer satellite developed at the University of Illinois.  It is a fully implemented, functional, embedded system with approximately 50,000 lines of code. A case study of the Dependency Analysis Management framework was performed on this system.

The dependency analysis involved mapping out all of the software components onboard ION, their associated failures, and the fault propagation rules attached to each failure. This dependency specification was then queried using DMF to determine any potential flaws in the design and implementation, as well as analysing the overall robustness of the system. A check for dependency inversions was done as well. Conclusion highlights include:

  • Flaws in seemingly minor components such as the message queues and analog converters could have potentially catastrohpic consequences.
  • A failure of the filesystem would have brough down the whole system because of a dependency inversion involving several critical components.
  • The design emphasized functional seperation, rather than criticality seperation resulting in a general lack of robustness and fault tolerance.

In an attempt to improve upon the failures of ION, the University of Illinois has begun design of ION2, which utilizes a distributed architecture.  A preliminary depenency analysis of this design was also conducted, and the results are encouraging.  From a design standpoint, all of the flaws of ION have been eliminted.  However, numerous flaws may yet creep in during the implementation.

Representative Publications

Hui Ding, Leon Arber, Lui Sha, Marco Caccamo. The Dependency Management Framework: A Case Study of the ION CubeSat. ECRTS. July, 2006.

Links

University of Illinois CubeSat Webpage
The Dependency Management Framework