Cooperative circumnavigating of unknown target by multi-UAV using only distance measurements

This paper proposes a distributed controller that utilizes only distance measurements to address the problem of cooperative circumnavigating an unknown target by Multi-Unmanned Aerial Vehicle (UAV) in a Global Position System (GPS) denial environment. Unlike most existing algorithms, this controller does not require location information of UAV and target. Firstly, a novel guidance control algorithm is designed to drive a single UAV to circle around the target by assuming that the actual distance measurement and the distance rate measurement are available. Secondly, a second-order sliding mode observer is utilized to complete the estimation of the distance rate in a finite time instead of the distance rate measurement. The observer is designed by using distance measurement information, allowing the UAV to complete the circumnavigation mission using only distance measurement. Then, on the basis of the designed distance circling controller, the finite time observer and the distance measurement information are used to complete the relative position estimation, and then a velocity coordination algorithm is developed to realize the uniform circumnavigation of the target by multiple UAVs. Finally, the numerical and Hardware-in-the-Loop (HIL) simulation results verify the effectiveness of the proposed method.