Constant Thrust Control Based on Double Threshold for Hovering at Asteroid Equilibrium Points

This paper proposes a dual-threshold control method for constant thrust of hovering orbit at the unstable equilibrium point of an asteroid. Firstly, according to the orbital dynamics model of the probe, the nominal hovering orbit of the probe near the equilibrium point is determined. Then, according to the basic idea of threshold control, not only set the threshold at the current moment, but also predict the state of the future moment and set the threshold at that moment. Only when both thresholds are triggered at the same time does the constant thrust engine come into operation, which keeps the detector on the hovering track. Finally, simulation was performed with Eros433 as the target asteroid. The simulation results show that the method can effectively reduce the number of engines switching and operating time while maintaining a certain accuracy.