Nonlinear control of a dual-quadrotor assembly

In response to the need for accurate position sensing in unmanned aerial vehicles (UAVs), we propose a concept aircraft in the form of a mobile global vision system. The dual-quad prototype resembles a miniature quadrotor nesting within a larger quadrotor. Inspired by the gaze stabilization abilities of hunting birds, the inner quadrotor is used as an actively stabilized sensor deck, while the outer quadrotor is used as a position-control flight deck. The sensor deck is stabilized to impose motion constraints on the visual odometry problem. This reduces the computational expense of implementing a vision system on a UAV where resources are limited. We propose a combination of feedback linearization, nonlinear transformation, and backstepping control. Results for aggressive flight maneuvers are demonstrated in simulation.