A new coordination framework for multi-UAV formation control

Official URL: http://risc01.sabanciuniv.edu/record=b1534446 (Table of Contents)

Unmanned Aerial Vehicles (UAVs) have become very popular in the last few decades. Nowadays these vehicles are used for both civilian and military applications which are dull, dirty and dangerous for humans. The remarkable advances in materials, electronics, sensors, actuators and batteries enable researchers to design more durable, capable, smart and cheaper UAVs. Consequently, a significant amount of research effort has been devoted to the design of UAVs with intelligent navigation and control systems. There are certain applications where a single UAV can not perform adequately. However, carrying out such tasks with a fleet of UAVs in some geometric pattern or formation can be more powerful and more efficient. This thesis focuses on a new coordination scheme that enables formation control of quadrotor type UAVs. Coordination of quadrotors is achieved using a virtual structure approach where orthogonal projections of quadrotors on a virtual plane are utilized to define coordination forces. This plane implies planar spring forces acting between the vehicles. Virtual springs are also augmented with dampers to suppress oscillatory motions. While the coordination among the aerial vehicles is achieved on a virtual plane, altitude control for each vehicle is designed independently. This increases maneuvering capability of each quadrotor along the vertical direction. Due to their robustness to the external disturbances such as wind gusts, integral backstepping controllers are designed to control attitude and position dynamics of individual quadrotors. Several coordinated task scenarios are presented and the performance of the proposed formation control technique is assessed by several simulations where three and five quadrotors are employed. Simulation results are quite promising.