Distributed collaboration with limited communication using mission state estimates

This paper describes a distributed system for collaboration and control of a group of mobile agents, such as unmanned aerial vehicles (UAVs) or unmanned ground vehicles (UGVs). The system allows a group of vehicles to work together to accomplish a mission via an allocation mechanism that works with a limited communication range and is tolerant to agent failure. This system could be used in a number of applications including mapping, surveillance, search, and rescue operations. The user defines the objectives of the group in terms of a mission plan. The mission plan contains a set of tasks, and each task contains a number of subtasks. A subtask is one objective that can be executed by a single agent, while a task is a series of related objectives that can be executed by one or more agents. Each agent in the group maintains information on the status of the mission in the form of a mission state estimate. The mission state estimate contains an agent´s current knowledge of the progress of each subtask in the mission. Whenever possible, agents share their mission state estimates and use an update protocol to produce updated estimates. This protocol is designed such that the most valid information available will propagate throughout the group. Agent decision-making is based on a combination of information from both the mission state estimate and the internal state of the agent. After checking the subtasks for completion, fault, and redo conditions, the agent selects the task and subtask for which it is best suited, taking into account its knowledge of the assignments and expected performance of others in the group. An execution module produces lower-level commands for the agent based on a set of subtask parameters. A simulated example mission demonstrates operation of the system