Cooperative drone payload delivery with self balancing tray

Recently, there has been increased interest in utilizing cooperative drones for payload deliveries. In prior work, all of the methods we know employ a pull-based method in which the payload dangles below the drones and is pulled from above by each drone to lift the payload. This approach suffers from instability induced by downwash from the drones on the payload, causing swaying of the payload. Instead, this paper explores an entirely new approach to cooperative lift in which the drones push a plate from below upon which a payload is placed, thereby avoiding downwash and swaying. We introduce the concept of a push-based self-balancing tray (SBT) above and between a pair of drones that integrates a three-degree end effector (3-DEE) control to help balance the payload during the lift. Experimental results demonstrate that the 3 DEE system significantly reduces vibrations, maintaining object stability at 3m/s.