Practical formation control of swarm robots using mobile agents

We propose an algorithm for controlling a set of actual swarm robots that compose specific formations. The swarm robots coordinate each other by using network communication, and compose formations such as specific symbols and characters. Our control algorithm achieves the network communication by using mobile software agents, which introduce control programs to each robot that has no initial program. Since the mobile agent can migrate from one robot to other robots through Wi-Fi network, and bring control programs on demand. Therefore we can introduce new control programs to the robots from outside as we want. We have made the mobile agents communicate each other through pheromone. A typical social insect ant uses pheromone as a communication means. In our robot control system, we have implemented ants and pheromones as mobile software agents. An agent called ant agent drives the mobile robot where it resides, and the other agent called pheromone agent guides to where the ant agent drives the robot. Each ant agent has only partial information of the formation. In order to spread the partial information among the neighbor robots, each ant agents generates pheromone agents and sends them to the surrounding robots. Dispatched pheromone agent looks for the ant agent it is assigned to guide through hopping around the robots. Once a pheromone agent has reached the robot with its target ant agent, the ant agent actually drives the robot by following the guidance of the pheromone agent, and composes the objective formation. In our research, we address the problems in implementing the previous naive algorithm using simplified robots, and make the algorithm suitable in the real world. In our practical algorithm, if an ant agent cannot keep driving its robot due to some other robots block its way, the ant agents migrates to the blocking robot to change the robot and makes the ant agent on the blocking robot take its previously driving robot. Then both ant agents resume keeping driving their exchanged robots to the target positions. We have implemented a simulator based on the algorithm and conducted experiments to demonstrate that our robot control system is practically feasible in the real world.