Adaptive fuzzy control for mobile robot obstacle avoidance based on virtual line path tracking

In unknown environments, a mobile robot moves toward a target point by tracking a virtual line path that connects the start point and the target point. Errors from wheel diameters, assembly and gearing may bring uncertain disturbance to the velocity of the mobile robot and enlarge the path tracking error. An adaptive fuzzy logic system is used to approximate the uncertain item in the path tracking control law so that the tracking error could tend to zero. The characteristics of the adaptive line path tracking controller are proved theoretically. When the robot detects any obstacle by sonar sensors, the target point is modified based on impedance control concept and a new virtual line path is generated. The mobile robot follows the new path and avoids collision with the obstacle. Experiments show the performance of the adaptive fuzzy line tracking controller and the obstacle avoidance method.