Context-Sensitive Plan Execution Language for Adaptive Robot Behaviour

Faced with the growing complexity of application scenarios for autonomous robots, context-awareness and adaptivity are becoming more and more essential abilities to determine environmental circumstances and to adapt to them accordingly. While semantic technologies are widely used for the modelling of a robot's context, purposive robot behaviour is typically described using plan or plan execution languages which lack explicit semantics for context representations. Context-sensitive adaptive behaviour emerges from the whole transformation process though, from context-awareness to the subsequent execution of associated plans. This comprehensive view of adaptivity lacks sufficient treatment in the field of robotics. Addressing this issue, we have augmented the expressive plan execution language PLEXIL, allowing complex context expressions as Description Logic queries to form an integral part of constructs that define sophisticated behavioural reactions. To demonstrate the symbiosis of context-awareness and plan execution, the enhanced language PLEXIL-DL is employed in the avionics system for a reconnaissance mission of an Unmanned Air Vehicle.