Efficient map synchronization in ad hoc mobile robot networks for environment exploration

Information sharing through explicit communication is necessary in many multi-robot applications in order to achieve effective decision making. However, unnecessary large volumes of communication data usually lead to time delay and energy waste. This paper addresses the problem of how to efficiently synchronize the map (or explored area) among multiple robots when they carry out cooperative area exploration or coverage. In this application, multiple robots need exchange map information in order to minimize the repeated exploration or coverage. When a connected ad hoc network can not be maintained, the map synchronization problem becomes more challenging. In this paper, a sequence number based map representation scheme and an effective map update tracking scheme are proposed. Based on them, an algorithm is developed to reduce the volumes of map exchange when robot subnetworks merge. Simulation results validate this algorithm.