Null space-based behavioral control applied to a formation of two quadrotors transporting a cable suspended load.

A controller based on the paradigm of virtual structure, considering two quadrotors transporting a cable-suspended load, is proposed, aiming at controlling the load movement through controlling the triangle quadrotor-quadrotor-load. The null space-based behavioral control technique is used, prioritizing preserving the formation shape and orientation. The objectives are to keep a safe distance between the vehicles, to prevent collision, and to reduce the load swing. Results of experiments run using the proposed controller are also shown, which validate the proposed approach. From the theoretical analysis and experimental results, the conclusion is that combining the virtual structure control paradigm with the null space-based behavioral control provides an effective solution for the problem of transporting a cable-suspended load using two aircraft, which is the main contribution of the paper.