In the field of mobile robotics, the process of robot localization and global trajectory planning in robot operating scenes, that are completely or partially known, represents one of the main issues that are essential for providing the desired robot functionality. This paper introduces the basic elements of path planning for an autonomous mobile robot equipped with sonar sensors, operating in a static environment. The path planning process is initially performed by using a known map. Next, the sonar sensors are used to localize the robot, based on obstacle avoidance techniques. The effectiveness and efficiency of the algorithm proposed in this paper is demonstrated by the simulation results.