Team Cooperation for Plan Recovery in Multi-agent Systems

The paper addresses the problem of recovering the execution of a multi-agent plan when the occurrence of unexpected events (e.g. faults) may cause the failure of some actions. We deal with a scenario where actions are executed concurrently by a group of agents organized in teams and each agent performs a local control loop on the progress of the sub-plan it is responsible for. When an agent detects an action failure, the agent itself tries to repair (if possible) its own sub-plan and if this local recovery fails, a more powerful recovery strategy at {\em team level} is invoked. Such a strategy is based on the cooperation of agents within the same team: the agent in trouble asks another teammate, properly selected, to cooperate for recovering from a particular action failure. The cooperation is aimed at achieving the goal assigned to the agents' team despite the action failure and to this end the agents exchange sub-goals and synthesize new plans.