针对可重复使用运载器(Reusable Launch Vehicle,RLV)再人轨迹在线规划问题,提出了一种基于割线法的标准轨迹快速生成方法.该方法以驻点热流、法向过载、动压和平衡滑翔限制为再入过程约束,以再入初始点和结束点的高度、速度为再人端点约束；在阻力加速度-速度平面内建立约束模型后,设计了折线形式的标准轨迹；采用割线法迭代计算轨迹转折点以调整轨迹形状,使最终规划轨迹对应的航程和终端点速度同时满足设计需求.最后取3种不同航程的再人情况进行了数值仿真.仿真结果表明,所提出的方法能够在1秒内完成再入轨迹规划,并在一定航程范围内适用,能够满足在线设计标准再入轨迹的实时要求.%A novel on-line planning method is proposed based on the secant method for RLV reentry trajectory design. Constraints during reentry are analyzed, and the stagnation point heat (low, the normal load, the dynamic pressure and the equilibrium glide constraint are selected as the main path constraints, also the heights and the velocities of the initial and terminal points are specified, all of which are expressed in D - V forms. The reference trajectory is then designed as a two-segment piecewise fold line. The secant method is utilized to adjust the turning point of the trajectory rapidly until the gliding distance and the velocity of the terminal point meet the desired values simultaneously. Finally, simulations are conducted for 3 cases with different the gliding distances. Simulation results demonstrate that the proposed method could not only design the on-line reference trajectory in less than 1 second, but also be applicable to a certain range of the gliding distance.
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