“…Contrasting with a single robot system, since the robots in the formation are interconnected with others, higher level control techniques have been required. Nevertheless, the formation control has been expected to be employed in various applications such as manipulation of large objects [ 1 , 2 ], intelligent highway systems [ 3 , 4 ], surface vehicle formation [ 5 ], flight formation systems [ 6 , 7 ], formation of multiple spacecraft [ 8 ], and surveillance systems [ 9 , 10 , 11 , 12 ] because the multi-robot system can provide certain advantages including cost reduction, sensing performance improvement, and higher robustness against robot faults. In particular, the robotic-sensor networks [ 10 , 11 , 12 ] in the surveillance systems have been a focus of attention because they reduce the cost of the surveillance systems and increase the performance.…”