Avoiding obstacles in mobile robot navigation: Implementing the tangential escape approach

This paper discusses the implementation of a new strategy to avoid obstacles when a mobile robot is navigating in a semi-structured environment. Such a strategy, the tangential escape, is conceived to allow the robot to navigate from a starting point to a destination point without colliding to any obstacle in its path. The deviation from any obstacle is performed according to an escape angle that makes the new robot orientation tangent to the border of the obstacle. First of all, the stability of such a control system is addressed, and the conclusion is that the robot always gets any reachable final destination. In the sequel, two implementations of such a strategy are discussed and compared. In the first one the sensorial apparatus onboard the mobile platform is a ring of ultrasonic sensors, whereas in the second one it is a laser sensor that delivers 180 range measurements covering a semi-circle in front of the robot. Results of the experimentation of both implementations are presented and discussed.