An Architectural Pattern for Goal-Based Control

Time-based command sequencing is the traditional paradigm for control of spacecraft and rovers in NASA´s robotic missions, but this paradigm has been increasingly strained to accommodate today´s missions. Goal-based control is a new paradigm that supports time-driven and event-driven operation in a more natural way and permits a melding of sequencing and fault protection into a single control paradigm. This paper describes one approach to goal-based control as an architectural pattern in terms of purpose, motivation, structure, applicability, and consequences. This paper is intended to help flight and ground software engineers understand the new paradigm and how it compares to time-based sequencing.