中文摘要：

针对带末端角度和末端速度约束的无人机空中加油自主会合问题,设计了一种3维分数阶滑模导引律,使无人机在无加油机主动配合的情况下具备自主会合能力.首先,根据无人机与加油机之间的相对运动关系,设计了3维比例导引规律,使无人机能够到达期望的加油位置.其次,利用滑模控制的强鲁棒性特点以及分数阶微积分的精细控制特性,基于变结构理论和李雅普诺夫稳定性理论设计了一种带有末端角度约束的3维分数阶滑模变结构控制律,并用所设计的分数阶滑模控制律对3维比例导引指令进行重构,使无人机能以期望的末端追踪角度到达加油位置.然后,构造了速度指令生成器,对无人机的末端速度进行约束.最后,对所设计的导引律进行了仿真验证,仿真结果表明所设计出来的导引律能满足追踪角度和速度约束的要求.

英文摘要：

A guidance law based on fractional-order sliding-mode control is developed to deal with the terminal angle and velocity constraints of unmanned aerial vehicle（UAV） in automatic rendezvous during air refueling. This law makes the UAV possess the ability to rendezvous with the tanker aircraft without active cooperation from the tanker aircraft.By considering the relative motion in three-dimensional space between the UAV and the tanker aircraft, we adopt the proportional navigation guidance（PNG） law in three-dimensional space to make the UAV fly to the desired formation point for refueling. Then, by making use of the robustness of the sliding-mode control and the meticulous characteristics of the fractional calculus, we develop a sliding-mode control law with fractional order to restrict the chasing angles of the UAV based on the variable structure control theory and the Lyapunov stability theory. The obtained sliding-mode control law with fractional order is employed to modify the PNG law, the resultant law will make the UAV possess the ability to fly to the desired formation point with the desired terminal chasing angle. Finally, a velocity command generator is developed to constrain the terminal velocity of the UAV. Simulations are carried out to validate the proposed guidance law; the results show that the designed guidance law achieves good control performance and satisfies the terminal angle constraint and the terminal velocity constraint.