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Sonar sensor based relative localization for leader-following formation control

Using sonar sensors is one of the most popular sensing methods for mobile robots, since the sensor is inexpensive and will simply give distance information. However, in general, the sonar sensor has difficulty in measuring the accurate direction of object while it is used to avoid obstacles such as large boxes, walls and so on since it has a large angle of beam. Nevertheless, this paper proposes to use the sonar sensors for localizing other robots as well as detecting obstacles, and represents the simplest algorithm to obtain the relative information: heading angle, bearing angle and distance between the leader and follower. A control algorithm for keeping (d, ϕ)-formation is presented by obtaining linear and angular velocities of the follower robot.