This paper studies the problem of dynamic coverage with wireless sensor and actor networks(WSANs) in underwater environment.Different from most existing works,the WSANs consist of two kinds of nodes,i.e.,sensor nodes(SNs) which cannot move autonomously and actor nodes(ANs) which can move autonomously according to the performance requirement.The problem of how to coordinate two kinds of nodes to facilitate dynamic coverage in underwater environment is challenging due to their heterogeneous capabilities.To reduce redundancy of communication links and improve connectivity between ANs and SNs in underwater WSANs,a min-weighted rigid graph based topology optimization scheme is first developed,such that the underwater communication energy consumption can be saved.With the optimized topology,a dynamic coverage strategy is proposed to improve the coverage among SNs and ANs for underwater WSAN where underwater fluid motions are considered.Furthermore,it is proved that the network coverage area is connected by using the min-weighted rigid graph.Finally,simulation results are presented to show the effectiveness of the main results.
In this paper,two methods of generating minimally persistent circle formation are presented.The proposed methods adopt a leader-follower strategy and all followers are firstly motivated to move into the leader’s interaction range.Based on the information about relative angle and relative distance,two numbering schemes are proposed to generate minimally persistent circle formation.Distributed control laws are also designed to maintain the desired relative distance between agents.The distinctive features of the proposed methods are as follows.First,only 2n 3 unilateral communication links for n agents are needed during the circle formation process and thus the communication complexity can be reduced.In addition,the formation topology is kept fixed for the whole motion and achieves a self-stability property.Finally,each follower keeps a regualr interval with its neighbors and the formation converges to a uniform circle formation.Simulation results are also provided to demonstrate the effectiveness of the proposed methods.
