ExecSpec: Visually Designing and Operating a Finite State Machine-based Spacecraft Autonomy System

The increasing complexity of modern spacecraft autonomy systems makes it difficult for engineers, mission operators, and domain experts to completely understand them during design and development and to analyze autonomy behavior during testing and flight operations. To address these problems, The Johns Hopkins University Applied Physics Lab is exploring a new visual programming approach to autonomy development based on a combination of finite state machines (FSM) and data flow diagrams. This allows autonomy developers to construct a system of reusable FSMs interactively and link them to form autonomy components and subsystems. This paper describes our current work creating such a visual autonomy development environment, called ExecSpec. It provides an overview of the system, discusses issues for handling the visual complexity caused by multiple state machine systems, and describes how mission operators can use visual monitoring tools during flight to analyze on-board autonomy status.