Here - Agents Lab - University of Nottingham

– Supporting both blocking and non-blocking intention dispatching for a newsubgoal: the former places the new generated plan at the front of the executionpath of the intention which generated the subgoal, the latter intendsthe new generated plan as a new intention.– Control on expansion of a subplan such as complete expansion before executionor incremental expansion in runtime.– Priority for execution of intentions.– Supporting atomic and continuous actions (actions which provide feedback)in blocking and non-blocking modes.6.2 Monitoring and Resource ManagementA cognitive robot has different goals and receives different events. In a BDIarchitecture, the robot generates different plans to achieve those goals and reactto those events. To provide a good level of autonomy and intelligence, it isobvious that a robot should be able to follow its different plans in parallel. Forexample when NAO is moving toward the drug box to check if it’s empty or not,it should be in the same time responsive to requests from its users (e.g. Task 5).The problem is that execution of different plans in parallel can be conflictingdue to a robot’s functional and resource constraints and should be coordinatedbased on the priorities of different plans. For example consider a use case inwhich NAO has picked up a piece of trash and going to put it into the trashcan. Suddenly, NAO hears a user asking for help. To be able to help the user,NAO should go to the Red Button and have empty hands to press it. As canbe noticed, this plan has two conflicts with the previous plan of the NAO (i.e.walking to the trash bin and having trash in hand). As helping the user is ofthe highest priority, NAO should leave the trash and start walking toward theRed Button immediately.To facilitate the use of agent programming languages for implementing controlsystems of autonomous robots, these languages should be extended withdifferent mechanisms and corresponding programming constructs necessary forcoordinating the parallel execution of different plans. Moreover execution ofplans should be monitored and their failures should be handled in a proper way.Current execution languages provide support for the following mechanisms:– Monitoring the execution of a plan at different levels of its hierarchy.– Monitoring different stages of the execution of a plan to guarantee its safeexecution. Some conditions should be checked before starting/resuming theplan, some conditions should be checked continuously during the plan executionand some should be checked after finishing the execution of the plan.– Monitoring different conditions such as temporal constraints on the absolutetime, constraints on execution statuses of other subplans, occurrence ofcertain events and constraints on a robot’s beliefs.– Representing and determining conflicts between different plans (e.g. explicitrepresentation by denoting the resources they require or by providing sharedvariables and locking mechanisms).50