In these flight tests the quadrotors are asked to follow predefined paths (computed off-line), while coordinating their position and attitude according to mission requirements. At the lower level, the developed path-following controller makes each quadrotor converge and follow its own path, independently of the temporal assignments of the mission. The algorithm relies on the implementation of a virtual vehicle running along the path, the rate of progression of which can be controlled at will. At the higher level, the quadrotors exchange coordination information over a supporting communications network to synchronize their position along the path as well as their attitude. The coordination and path-following algorithms have been implemented in MATLAB Simulink, and use feedback data from a Vicon Motion Tracking system to produce the control commands. The UAVs communicate with each other directly on Simulink, at a frequency rate of 100Hz. The Vicon positioning system sends feedback data at a rate of 100Hz.
The efficacy of the cooperative control framework has been evaluated on Parrot AR.Drone flying platforms. The AR.Drone is equipped with an internal autopilot which accepts roll angle, pitch angle, yaw rate, and vertical speed, as path-following commands. For this reason, the path-following algorithm presented in [3] has been implemented. The path-following commands are sent to the onboard autopilot at a rate of 30Hz.
The flight tests have been performed in the Center for Autonomous Vehicle Research (CAVR), Naval Postgraduate School, Monterey, California.
For additional information, contact Venanzio Cichella.

 

Two quadrotors coordinate their positions along predefined paths by exchanging information over a supporting network.

 

Two quadrotors dancing Tango. A sequence of trajectories is computed off-line. The song is played in MATLAB Simulink. The sound wave of the song plays the role of an input to the path generator. According to the beat of the song, the path generator switches between different trajectories. The coordination algorithm ensures that the quadrotors coordinate along the trajectories every time, therefore coordinating with the song too! The result is pretty sweet!

 

 

References
  1. V. Cichella, I. Kaminer, V. Dobrokhodov, E. Xargay, R. Choe, N. Hovakimyan, P. Aguiar, and A. Pascoal. Cooperative path-following control of multiple multirotors over faulty networks. In IEEE Transaction on Automation Science and Engineering, Vol: 12, Issue: 3, 2015
  2. V. Cichella, R. Choe, S. B. Mehdi, E. Xargay, N. Hovakimyan, I. Kaminer, and V. Dobrokhodov. A 3D path-following approach for a multirotor UAV on SO(3), IFAC RED-UAS, Compiegne, France, 2013.
  3. V. Cichella, I. Kaminer, E. Xargay, V. Dobrokhodov, N. Hovakimyan, P. Aguiar, and A. Pascoal. A Lyapunov-based approach for time-coordinated 3D path-following of multiple quadrotors. In Proceedings of 51st IEEE Conference on Decision and Control (CDC), 2012.