A hybrid reentry guidance algorithm is developed for a reentry vehicle.The online piecewise trajectory planning based on waypoints and trajectory tracking guidance algorithm are incorporated.The dimensionless kinematic equations of the reentry vehicle and the longitude-latitude expressions are established in guidance coordinate frame(GCF).The reentry constraints are described and incorporated in the proposed guidance algorithm.The way points based on the initial reference trajectory are designed to piecewise implement trajectory planning.The linear quadratic regulator(LQR)controller is designed to implement longitudinal guidance,and the lateral error boundary is given to determine the sign of the bank angle.Simulation and experimental results indicate that the average calculating time of each trajectory planning is less than 0.2 seconds and the guidance accuracy requirements are satisfied as well.%针对在线轨迹规划与跟踪,提出了一种混合再入制导方法.该方法将基于航路点的分段轨迹规划与轨迹跟踪制导有效地结合起来.首先给出再入飞行器无量纲运动方程,建立制导坐标系(GCF),并推导了新坐标系下的经纬度表达式.并将再入飞行过程中各种飞行约束条件转换为控制变量约束.为了加快轨迹优化速度,设计了初始再入飞行轨迹和相关航路点,给出了基于航路点信息的分段轨迹在线规划方法.纵向飞行轨迹跟踪采用基于线性二次型调节器(LQR)的方法,横侧向制导采用横向误差走廊的方法进行控制.仿真结果显示,该方法在线轨迹规划平均计算时间小于0.2秒,且具有较高的制导精度.
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