基于在线轨迹迭代的自适应再入制导

针对传统轨迹跟踪制导方法在再入飞行中无法较好适应导航模式切换等突变状况的问题，提出了一种能够有效应对制导系统输入信息不连续性的自适应在线轨迹生成方法。该方法通过实时的多项式拟合以及迭代过程确定满足终端约束条件的高度-速度剖面，并解算出当前飞行状态下所需的攻角与倾侧角指令，从而平稳、精确地将飞行器引导至末端能量管理段。通过对速度与能量、高度、轨迹倾角以及待飞航程等状态量建立解析关系，该方法拥有迭代速度快以及收敛性强的优势。仿真结果显示，该方法对输入信息的误差及跳变等不确定因素的适应性很强，在各类干扰情况下较传统方法拥有更高的制导精度。相较于传统轨迹跟踪制导方法，该方法在实际应用背景下显著地提升了制导的自主性与适应性。

Adaptive reentry guidance based on on-board trajectory iterations

An adaptive method for on-board generation of entry trajectory is presented to effectively tackle the discontinuity of the input data of the guidance system, as the traditional trajectory-tracking guidance method cannot well adapt to saltatorial conditions such as the switch of navigation modes. By real-time polynomial fitting and iteration, the desired altitude-versus-velocity profiles satisfying the final constraints are determined, and then the corresponding angle of attack and bank angle commands are obtained, which guide the vehicle to safely and accurately reach the terminal area of energy management. This method enables the iterations to be fast-converging, as it takes the advantage of building analytical relations between velocity and the state variables including energy, altitude, flight-path angle and range-to-go. Numerical simulations indicate that this method has a strong adaptability against uncertainties such as the error and the saltation of the input data, as well as a better accuracy than the traditional method under various dispersion conditions. It is also proved that this method significantly enhances the autonomy and adaptability of entry guidance under practical application circumstances, compared to the traditional trajectory-tracking guidance method.