无人机编队机动飞行时的队形保持反馈控制
A Formation Keeping Feedback Control for Formation Flight of UAVs

为提高编队大机动时的队形保持能力,采用虚拟结构编队方法,基于李雅普诺夫直接法设计独立的非线性队形保持控制器,并在此基础上采用非线性模型预测控制方法设计含队形反馈的编队轨迹跟踪器。通过在代价函数中引入队形误差代价来实现队形反馈控制策略,并采用动态参数实现编队队形保持和沿参考轨迹飞行之间的自适应切换,各无人机通过滚动求解有限时域优化问题得到虚拟结构的控制指令。仿真结果表明,相较于无队形反馈的情况,所设计的含队形反馈轨迹跟踪器能够显著地降低编队大机动时的队形保持误差。
When executing a sharp maneuver, if the formation maneuver path is not well designed, a formation of UAVs constrained by their performance capabilities, may not be able to keep in satisfactory formation as desired. We, applying Lyapunov stability theory and using virtual structure approach, propose designing individually a nonlinear controller for satisfactory formation keeping. Then, by applying nonlinear model predictive control approach, a trajectory tracker with formation feedback is designed to improve the capacity of formation keeping during a sharp maneuver. Formation feedback is achieved by adding a formation-error cost to the total cost function, and a dynamic parameter is proposed to obtain a trade-off between formation keeping and flying along prescribed trajectory adaptively. Each UAV gets the reference commands of the virtual structure by solving a Finite Horizon Optimal Control Problem at each time step. Simulation results and their analysis suggest that, compared with situation without formation feedback, the designed trajectory tracker with formation feedback can reduce formation-keeping error evidently