Noncertainty-equivalent observer-based noncooperative target tracking control for unmanned aerial vehicles

Target tracking is a typical and challenging scenario that is required to be executed by unmanned aerial vehicles(UAVs) in operational environments. This work investigates the noncooperative target tracking control problem for UAVs. An integrated model is constructed by combining the dynamics of both the line-of-sight variables and the acceleration components. Particularly, the dynamics of the acceleration components, that contain unmeasurable states, characterize the relative motion between the noncooperative target and the UAV. To estimate these states, a globally convergent observer is developed by utilizing the noncertainty-equivalent(NCE) structure. With the integrated model and the NCE observer, an output-feedback target tracking control scheme is proposed using the dynamic surface control technique and the prescribed performance control method. Based on the Lyapunov approach, the relative spatial positions of the target and the UAV are proved to always stay within a specified operation region and ultimately converge to a small terminal region. Finally, simulation results are presented to illustrate the effectiveness of the proposed target tracking control scheme.