Switched Control Strategy for Robust Formation Flight with HIL and In-Flight Validation

In recent times, Unmanned Aerial Vehicles (UAVs) have been intensively studied for a wide range of military and civil applications such as surveillance and reconnaissance missions, agriculture, traffic monitoring, pollution control, meteorological data collection, pipeline survey, early fire detection, rescue missions, wildlife population monitoring, etc. The above tasks can be carried out faster and more efficiently by a group of UAVs flying in formation. This paper presents the application of two stage switching controller in autonomous formation flight of UAVs based on the leader follower configuration. The constructed UAV airframe, as well as the autopilot, formation flight control unit and wireless communication link for data sharing between UAVs were presented and described. The advantages of the switched control were demonstrated in terms of a significantly larger region of stability in maintaining formation, as opposed to the standard, one stage control laws with classical compensators. Hardware In The Loop (HIL) tests of proposed formation flight control were performed, during which the inertial states and flight parameters were logged. The HIL test rig enabled us to verify the formation flight control performance which was further substantiated by actual flight tests.