E Khanmirza - Assistant Professor, Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran,16846-13115
M.M Amini Farshchi - M.S. Graduated, Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran, 16846-13115
A Maghsoudi - M.S. Student, Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran, 16846-13115

Quadrotor or quadcopter is vertical flight vehicle which is made by four propellers in each side like plus sign. So, its name is chosen because of this tructure. This configuration allows quadrotor to have easy and precisemovement in all directions so it cause quadrotor to have excellent maneuverability. In spite of their simple appearance, these vehicles are very complex. Nowadays, a lot of projects and activities have focused on quadrotors, because of their applications. The most important and harsh ones are guidance and control of quadrotors. In other words, it is so important for quadrotors to move towards their destination without having any accident with obstacles in their ways. This paper explain how directions of a quadrotor is controlled automatically in a dynamic environment. In this regard, a quadrotor is chosen and equipped by an ultrasonic sensor for its position controlling. After simulation and design control system, quadrotor could identify the obstacle which was a ring swinging in front of it. So, it could move towards its destination without colliding. Finally, practical experiment proved correctness of control system design as well.

Quadrotor, position control, dynamic environment, ultrasonic sensor