Localization and circumnavigation of multiple agents along an unknown target based on bearing-only measurement: A three dimensional solution

In this paper, the localization and circumnavigation problem of an unknown stationary target is investigated. Unlike most existing results in which single agent is considered in two-dimensional (2D) space, in this paper multiple agents circumnavigating the target in three-dimensional (3D) space is addressed. Thus, new algorithms are needed to drive multiple non-coplanar agents to the same plane, and the coordination among the agents is also involved here. In addition, the agents measure only the bearing information to the target and each agent does not necessarily know the global normal vector of the objective orbit. An estimator is first established to localize the unknown position of the target and the control protocols are then designed to achieve the 3D circumnavigation of the target. Furthermore, the coordinators for the case with and without global orientation are designed, subsequently, the uniform circumnavigation and even circumnavigation are, respectively, achieved. Simulations are conducted to validate the benefits and effectiveness of the proposed method.