Research on Adaptive Guidance Technology for Lunar Emergency Ascent

In this paper, an adaptive guidance method is studied for the emergency ascent of the lunar surface. Firstly, according to the principle of maximum value, the two-point boundary value problem of maximum energy entering orbit under five constraints is derived and established. Secondly, a two-layer iterative solution strategy is designed. The inner layer uses Newton iteration to solve the two-point boundary value problem of maximum energy into orbit, and the outer loop adjusts the time to make the speed meet the target speed. In the outer loop iteration, a time iterative adjustment strategy is designed. In the inner loop, according to the change rule of the thrust direction in the task, a strategy for selecting the initial value of the principal vector of the covariant variable is designed to solve the two-point boundary value problem. The simulation results show that the guidance law designed in this paper can converge reliably, and the target parameter binding is simple. It can adapt to coplanar ascending tasks and different-plane ascending tasks. In the presence of second consumption and specific impulse deviation, it still has high guidance accuracy.