Cooperative control of multiple unmanned aerial systems for heavy duty carrying

摘要

The idea of cooperative carrying using a team of unmanned aerial vehicles (UAVs) has been viewed as a widely applicable and deployable use of unmanned multi-agent systems, yet there are very few working systems that can successfully perform such tasks due to the complexities involved. One of the primary challenges is the limited control authority of the cooperative team due to the scale of the individual agents being necessarily much smaller than the load. Here, we propose a general method that can be used to optimise the control authority of a UAV team in the case where the agents are rigidly mounted to the payload. Firstly, a tilt angle for each UAV relative to the payload is introduced to improve the yaw control of the system, as a large wide payload will invariably have a large moment of inertia in the yaw axis. The positional placement of the UAVs and the value of the tilt angle that maximises control authority was then found using an evolutionary algorithm. The optimised solution based on a case study task involves using four UAVs placed at the corner of a square payload with an inward tilt, which can be effectively controlled as a single large quadrotor. Testing results show that the full system carrying the payload can execute given trajectories autonomously with high accuracy and precision, effectively performing the task of cooperative carrying. The proposed system was successfully demonstrated at the 2017 International Micro Air Vehicles Competition.