高超声速飞行器平稳滑翔弹道设计方法

针对已知攻角和倾侧角的高超声速飞行器平衡滑翔再入问题,提出了满足纵向加速度变化率最小的平稳滑翔弹道概念,并给出了平稳滑翔弹道设计方法.首先采用正则摄动的方法对高度动态微分方程进行求解,获得了精度较高的平稳滑翔高度、弹道倾角和纵向加速度解析解.然后对平稳滑翔弹道的动态特性进行了分析,结果表明该弹道具有自然稳定性和弱阻尼性.进一步给出了弹道振荡的自然频率和阻尼表达式,其中自然频率仅与速度相关,而阻尼则与速度和纵向升阻比相关.最后,通过比较高度偏差的比例反馈、微分反馈和比例+微分反馈3种方案,得出纯微分反馈是实现平稳滑翔的最佳方案,并给出了定阻尼微分反馈系数的表达式.仿真校验表明:该方案具有控制平滑、弹道振荡收敛速度快及鲁棒性好等特点. 

Steady glide trajectory planning method for hypersonic reentry vehicle

The concept of steady glide trajectory with minimum integration of the change rate of longitudinal acceleration was proposed for the equilibrium glide problem with given angle of attack and bank angle profiles, and the planning method of the steady glide trajectory was described. First, the dynamic differential equation in the altitude direction was solved by regular perturbation, and steady glide analytical solutions with high precision, including height, flight path angle and longitudinal acceleration, were obtained. Then the dynamic behaviors of the steady glide trajectory were analyzed, the natural stability and low damping of the trajectory were found, and the expressions of natural frequency and damping were obtained. The results show that the natural frequency is only a function of velocity, while the damping depends on velocity and longitudinal lift-drag ratio. Finally, the pure differential feedback of height deviation is found to be the best scheme for restraining the oscillations of the steady glide trajectory among three feedback schemes, which are pure differential feedback, pure proportional feedback and proportion-differential feedback. The simulation results show that the control of the pure differential feedback scheme is steady, the trajectory oscillation decay fast, and the robustness of the scheme is excellent.