吸气式高速飞行器爬升-巡航轨迹在线优化

Online Optimization of Ascent-Cruise Trajectory for Air Breathing High Velocity Vehicle

针对吸气式高速飞行器的大气层内爬升和巡航飞行段,进行了在线轨迹优化设计。与传统的爬升段结合定高定速巡航轨迹形式不同,采用优化的方法得到的轨迹能够保证性能指标的最优性。首先,将轨迹优化问题建模为非线性最优控制问题,控制量包括攻角、倾侧角以及燃油当量比。然后,对问题的非线性进行了处理,将变量进行离散化,得到凸优化问题。分析了飞行器的气动和推力特性,设计了优化变量的初始参考。最后,设计算法的外环迭代策略,将每一次求得的解作为参考轨迹进行下一次迭代计算。数值仿真结果表明,该方法能够解决吸气式高速飞行器爬升巡航段轨迹优化问题,并且求解时间满足在线轨迹优化要求。

In this paper,the online ascent-cruise trajectory optimization for air breathing high velocity vehicle is provided.Different from the traditional ascent phase combined with steady-state cruise phase,the trajectory obtained by the optimization method can ensure the optimality of performance index.Firstly,the trajectory optimization problem is modeled as a nonlinear optimal control problem,and the control variables include angle of attack,bank angle and throttling coefficient.Then,the nonlinearity terms in the dynamics are approximated by linearization,the variables are discretized,and the convex optimization problem is obtained.The aerodynamic and thrust characteristics of the vehicle are analyzed,and the initial reference of the optimization variables is designed.Finally,the outer loop iteration strategy of the algorithm is designed,and the solution obtained each time is used as the reference trajectory for the next iteration.The numerical simulation results show that this method can solve the trajectory optimization problem in the ascent-cruise phase mentioned in this paper,and the solution time is less than that of trajectory optimization software based on nonlinear programming algorithm,which meets the requirements of online trajectory optimization.