A geometric control is proposed for the trajectory-tracking of a quadrotor unmanned aerial vehicle with suspended load. The plant to be controlled is modelled by using Euler-Lagrangian equations, and it is linearised around zero swing angles of the load. The swing angles of the load are supposed to be unmeasurable, and they are estimated by the state observer. The controller is design in the inner-outer loop framework, where the outer loop trajectory-tracking is basically implemented by internal model principle, and the inner loop attitude control is designed on SO(3) to avoid singularities. It is proved that, with the proposed geometric control, the tracking error of the inner loop converges in finite time, and the outer loop trajectory tracking error is asymptotically stable. Theoretical results are substantiated by a numerical example, where the closed-loop system is capable of tracking a circular curve.

No abstract