Fuzzy Speed Controller for Mobile Robots Navigation in Unknown Static Environments Yahya Tashtoush and Israa Haj-Mahmoud Computer Science Department, CIT, Jordan University of Science and Technology yahya-t@just.edu.jo, israa_haj_mahmoud@yahoo.com ABSTRACT Mobile robots that navigate in unknown environments should be provided with a module that is responsible for controlling its speed. In this paper, a new fuzzy speed controller is offered to control the speed of a mobile robot that navigates in unknown static environments. The proposed controller considers three factors; the turning heading angle taken by the robot for each step, the distance to the nearest obstacle, and the importance of each sensor. Simulation results show an enhancement in the robot behavior (in terms of time and route) when the proposed fuzzy controller is used as compared to the same robot with constant speed. KEYWORDS Fuzzy speed controller, mobile robot, unknown environment, navigation system 1 INTRODUCTION In real life applications of mobile robots such as space robots, robots employed to help in rescue missions in catastrophic conditions, and robots deployed in military applications, reducing the time that a robot takes to reach a target point is considered crucial and of critical importance. For example, in rescue missions, some extra few minutes for a robot to find injured people will possibly stand as a boundary between life and death. Controlling the speed of a mobile robot is an important issue regardless of the navigation environment type, but in unknown navigation environments, controlling the speed becomes a challenge. In unknown environments the robot’s only way of detecting objects and obstacles is via its sensory system. One of the simplest types of sensors is ultrasonic sensors. The speed of a mobile robot should be optimized according to the surrounding obstacles. Speed optimization can reduce the time taken by the robot to reach a specified destination. For example, in less crowded areas, the robot should move faster, while it should move slower in crowded areas to avoid collisions. The speed should also depend on the distance between the robot and the nearest obstacle. Moreover, the angle in which the robot will move in every step, is another factor to be considered. If the robot tends to make a turn in a wide angle, it must reduce its speed to avoid accidents caused by the centrifugal force, exactly the same situations encountered while driving a car in real life. In this paper, a fuzzy system is proposed to precisely tune the robot’s speed according to a number of factors including the distance to the nearest obstacle, the turning heading angle, and the importance of the sensor’s reading. Considering the factors included, the proposed fuzzy speed controller imitates the way of a car driver controls the speed. The proposed system is tested by simulation within a wide range of different environments in a try to include as much cases as possible. The rest of this paper is organized as the following: The next section is a glance at the navigation system and section 4 is a literature review of recent studies in this field. Section 5 describes the proposed fuzzy speed controller in details. Section 6 illustrates simulation results. Section 7 concludes the study and possible future work. 2 THE BASE NAVIGATION SYSTEM In our study on path planning for mobile robots [1], Al-Jarrah and me introduced a navigation system that imitates the human driver by using ISBN: 978-0-9891305-1-6 ©2013 SDIWC 139