Localization and circumnavigation of an unknown target using distance measurements in 3D space

This paper investigates the problem of localization and circumnavigation of an unknown stationary target in 3D space using distance measurements. An estimator is first designed in 2D space to locate the target, with which a control protocol is proposed to force the agent to travel along a circular trajectory around the target. Then the algorithm is extended to 3D space to circumnavigate the target under the condition of obtaining gravity direction additionally. In particular, the agent moves alternately in the X-Y horizontal planes and the X-Z vertical planes in different patterns under different switching conditions, which is beneficial to monitor the target from a broader perspective. Meanwhile, the rigorous stability analyses of two cases are given in terms of the Lyapunov method. Finally, the effectiveness of the proposed algorithms is verified through numerical simulations and a real experiment.