Patent ID: 7486633

Claim:
A network system for forming a network topology with a plurality of nodes each having a radio communication function and a traveling function and operating in a self-directive and dispersive state, wherein each node has first and second states in which the node travels with said traveling function and searches for information for connectivity with neighboring nodes and a third state in which travel with said traveling function is stopped, and a node in the first state shifts to said third state when a first condition is satisfied and a node in the second state shifts to the third state when a second condition different from said first condition is satisfied, and each node finally shifts to said third state dynamically switching between said first state and said second state to form a network topology, wherein said node has a sensor, and said first state is an Expand state in which the node travels and searches for a position where connectivity with neighboring nodes is obtained to expand a network topology; said second state is a Bridge state where the node travels and searches for a position where connectivity with neighboring nodes is obtained to connect independent local topologies; and said third state is a Stay state where the node stops at the current position to become a component of the network topology, wherein a node in the Expand state shifts to the Stay state under the first condition under which the node can be connected to an neighboring node in the Stay state, and wherein a node in the Expand state transmits a second signal to said connectable neighboring nodes in the Stay state and shifts to the Stay state upon reception of a third signal.