An Approximate Optimal Explicit Guidance Method with Fully Controllable Position and Velocity During Dynamic Descent

Abstract

The invention relates to a position speed controllable quasi-optimal explicit guidance method in a power decrease process; the quasi-optimal explicit guidance method respectively use the maximum thrust and minimum thrust as input values, and uses a normal thrust power explicit guidance method to calculate guidance parameters and predict terminal positions corresponding to the thrusts; according to a relation between a target position and predicted terminal positions under two different thrusts, the quasi-optimal explicit guidance method can automatically determine whether to use the maximum thrust or the minimum thrust to guide, thus realizing automatic switching between the maximum trust and minimum thrust. The invention only relates to two PEG guidance rules for calculation, and the computational complexity is smaller when compared with an iteration thrust adjusting mode; the thrust control uses an automatic maximum-minimum switching mode, an engine usage efficiency is higher than continuous variable thrusts, so propellant consumption is theoretically least.

Description

technical field [0001] The invention relates to an approximate optimal explicit guidance method with fully controllable position and velocity in the process of power descent, which belongs to the field of lunar and deep space exploration guidance control. Background technique [0002] For the soft landing mission of an extraterrestrial body without an atmosphere, the probe needs to continuously reduce its flight altitude and speed under the action of the braking engine, and gradually approach and land vertically on the surface of the celestial body. The control of the flight trajectory during the powered descent is accomplished under the action of the guidance law, so the actual flight effect, including the position, speed, attitude of the terminal and the propellant consumption during the entire flight process, all depend on the design of the guidance law. [0003] Taking the lunar power descent process as an example, the early probes used gravity turning guidance, which re...

AI Technical Summary

Problems solved by technology

There are various problems in the existing methods, some do not have the position control ability, some do not have the optimality of propellant consumption, some have a large amount of calculation, and some have higher requirements for the variable thrust engine (the range of continuous variable thrust of the engine is limited and low specific impulse)

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