基于伪谱法的小型超音速无人机轨迹优化

Trajectory optimization of small supersonic unmanned aerial vehicle based on pseudo-spectral method

为了提高小型超音速无人机的经济性能,针对配备加力燃烧室导致设计复杂、油耗过大的问题,提出小型无加力燃烧室的超音速无人机.利用马赫俯冲机动突破音障,基于hp自适应伪谱法的最优控制轨迹规划方法,求解达到超音速巡航飞行的最小油耗和最小时间2种轨迹最优化问题.该方法将控制与状态变量离散化,结合无人机飞行的物理过程,将多约束最优控制问题转化为非线性规划问题.将本文与传统飞行方案所得的结果进行比较,分析重要设计参数对最优轨迹的影响.仿真结果表明,利用该方法能够有效地规划出无人机从高亚音速到超音速飞行过程中的可行轨迹,得到的最小油耗、最小爬升时间均优于传统飞行方案,最小油耗降低约11%,最小爬升时间降低约46%.

A new supersonic unmanned aerial vehicle(UAV) with a powerless combustion chamber was proposed to solve the problem that the design was complicated and the fuel consumption was too high in order to improve the economic performance of small supersonic UAV. A trajectory optimization of the new UAV based on hp adaptive pseudo-spectral method was proposed to optimize the trajectory with the target of the minimum fuel consumption and minimum time in a flight section which shall make the UAV reach supersonic cruise flight by introducing the Mach subduction maneuver. The control variable and state variable were discretized, and the multi-constraint optimal control problem was transformed into a nonlinear programming problem by combining with the physical process of the UAV flight. The proposed optimal trajectory was compared with the conventional flight schemes, and the effects of critical design parameters on the optimal trajectory were analyzed. The simulation results show that the proposed method can effectively plot a feasible path which shall make the UAV climb from high subsonic to supersonic flight. The obtained minimum fuel consumption and minimum climb time are better than the traditional flight scheme. The minimum fuel consumption was reduced by about 11%, and the minimum climb time was reduced by about 46%.