圆形轨迹导引下的无人机事件触发抗干扰环绕控制

针对内部不确定性以及外部环境摄动的目标环绕控制问题，在基于反步法的双层制导框架下，利用级联控制思想，提出了一种圆形轨迹导引下的四旋翼无人机事件触发抗扰环绕控制方法。在轨迹回路中，构建了可满足持续激励条件的目标位置估计器，保证仅通过视线方位角就能获取可满足最终一致有界条件的目标估计项。随后，基于目标的位置估计结果，设计了目标环绕控制律生成线速度指令，并通过方向向量场验证了该环绕制导律的有效性，消除了现有李雅普诺夫向量场制导(LVFG)对相对位置和目标速度的依赖。在姿态回路中，通过采用扩张状态观测器(ESO)补偿系统的集总不确定性，设计了基于相对阈值事件触发控制的姿态控制器，在有效降低控制器到执行机构之间信号传输频率的同时，实现了四旋翼无人机对静止/移动目标环绕。然后，借助输入状态稳定性定理证明了系统的稳定性。仿真结果表明，所提控制方案能够实现圆形轨迹导引下四旋翼无人机对静止/移动目标的环绕监视。

Event-triggered anti-interference circumnavigation control for UAV based on circular trajectory guidance

To handle the problem of target circumnavigation control considering internal uncertainties and external environmental perturbations, employing a cascaded control approach, an event-triggered anti-disturbance circumnavigation control method for quadrotor under circular trajectory guidance within a two-layer guidance framework based on the back-stepping method is presented. In the trajectory loop, a target position estimator which can satisfy the condition of continuous excitation is constructed, guaranteeing that the target estimator which meets the final uniformly bounded condition can solely obtained by means of line-of-sight azimuth angles. Subsequently, based on the estimated target position, a target circumnavigation control law is designed to generate linear velocity commands, and the effectiveness of the circumnavigation control law is validated through a directional vector field, eliminating the dependence on relative positions and target velocities as seen in the existing Lyapunov vector field guidance (LVFG) methods. In the attitude loop, by compensating the lumped uncertainties in the system using an extended state observer (ESO), an attitude controller based on relative threshold event-triggered control is designed, which effectively reduces the signal transmission frequency between the controller and the actuators enables quadrotor to circumnavigate stationary and moving targets. Then, the stability of the system is proved utilizing the input-to-state stability theorem. Finally, simulation results demonstrate that the proposed control scheme realizes circumnavigation and surveillance of stationary/moving targets by quadrotor under circular trajectory guidance.