Formation control of unmanned vehicles is an active field of research. Control of autonomous robots without a navigator has drawn significant attention due to lack of access to information about global positioning system in situations such as underwater or under other fluids. Under these situations, finding a way to lead the agents towards the desired formation can be helpful. Therefore, a signal generating source or agent is considered as the leader and the rest of the agents as followers. In the leader-follower setting, the agents receive the signal from the virtual leader (source) and form the desired formation. Using this, the agents measure and control their displacement from the leader. Formation control has multiple aspects in engineering. This work is not only form the formation. By forming the formation, following the leader while maintenance the formation and not colliding the obstacles in the path becomes crucial. When the number of the agents exceeds one, the collision of the agents seems inevitable. In this condition, navigation function can prevent the collision of the agents with obstacles and with each other. Although there exist several methods for formation control, it is necessary to localize the leader (signal generating source) in the leader-follower structure. Thus, the leader localization is navigated with extremum seeking control. The agents measure the signal generated by the leader and since the intensity of this signal is maximum in the position of the leader, extremum seeking control leads them to this position. Now leader localization by the agents and using biased extremum seeking control, the displacement of each agent from the source is controlled. Therefore, using this approach, we can control and form the polygonal formation of holonomic agents over an unknown source. Key Words : Formation Control, Extremum Seeking Control, Leader Localization, Obstacles Avoidance
