Emphasizing Understandability, Flexibility, and Verifiability in a Spacecraft Fault Management Autonomy System
George Cancro, Russell Turner, Christopher A. Monaco, Daniel Wilson, L. Nguyen, Michael J. Pekala, Chris Olson, Eliezer G. Kahn · AIAA Infotech@Aerospace Conference · 2009
Surveying the current state of practice of spacecraft autonomy, one can detect many different attributes of the various autonomy systems currently employed to maintain the safety of the spacecraft. In an effort to move beyond the state of practice, Johns Hopkins University Applied Physics Lab has focused on three of these attributes not found together in current systems: Understandability, Flexibility and Verifiability. Understandability defines the ability to specify and review the autonomy system in such a way that any non-software domain expert or system engineer can understand the design. Flexibility defines the ability to modify the design pre- and post-launch in parts without patching or without complete code uploads. Verifiability defines the ability to exhaustively and rapidly verify correct autonomy system behavior before it is uploaded to the spacecraft. With the goal of attaining all three of these attributes, JHU/APL has designed and developed a new autonomy system called ExecSpec (short for Executable Specification). The system has been progressed to TRL 5 and is now poised for infusion into future spacecraft programs. ExecSpec is a new visual programming approach to autonomy system development that enables any system designer or domain expert to visually create spacecraft