plexil

PLan EXecution Interchange Language from NASA for robot control

PLEXIL (Plan Execution Interchange Language) is a language for representing plans for automation, as well a technology for executing these plans on real or simulated systems. PLEXIL has been used in robotics, control of unmanned vehicles, automation of operations in human habitats, and systems and simulations involving intelligent software agents. PLEXIL was designed initially to meet the requirements of flexible, efficient and reliable plan execution in space mission operations. It is compact, semantically clear, and deterministic given the same sequence of events from the external world. At the same time, the language is quite expressive and can represent branches, loops, time- and event- driven activities, concurrent activities, sequences, and temporal constraints. The core syntax of the language is simple and uniform, making plan interpretation simple and efficient, while enabling the application of validation and testing techniques.