A low-cost estimator for target localization and circumnavigation using bearing measurements

In this paper, a scalar target estimator is designed to solve the problem of localization and circumnavigation for a stationary or moving target by one agent using the agent's known position and its bearing-only measurements of the target. The estimator is low-cost because only scalar rather than vector estimation is involved, where the estimate of the target is fixed in the line passing the agent and the target. Meanwhile, a control protocol is adopted to force the agent to move on a circular trajectory around the target. When the target is stationary, we show that the new estimation method provides a mechanism for collision avoidance, which means that the agent keeps a comparatively large distance away from the target in the whole circumnavigation process. When the target is moving, the new estimator guarantees boundedness of the distance between the agent and the target, and a concrete bound of the distance is proposed. The corresponding convergence and stability analyses are provided subsequently. Simulations are conducted to verify the proposed method.