Multi-orbit circumnavigation control of UAVs with arbitrary angular spacing in three-dimensional space

In this paper, a novel multi-orbit circumnavigation control law is proposed for a group of UAVs with arbitrary angular spacing based on local information. By constructing the actual relative velocity and the ideal relative velocity in three dimensional space, the circumnavigation control problem of moving target is first transformed into a relative velocity tracking problem. Further, to remove the limitation that the UAVs require the global information of the moving target, the corresponding fixed-time convergent estimators with the cyclic directed graph are developed. Based on these distributed estimators and relative kinematics equations, the dynamic linear feedback is introduced to derive the distributed control law. At the same time, the angular spacing update law and the circumnavigation radius coefficient are designed, so that the UAVs can circumnavigate on multi-orbit with any angular spacing. Finally, the exponential stability of the control law is proved by Lyapunov method, and the effectiveness of the control law is verified by five examples.