Landing Guidance And Control Of Asteroid Detector

Since the 21 st century,various countries and organizations have shown great interest in the field of deep space exploration.The detection of asteroids and comets is the focus of deep space exploration.The United States,Europe,Japan and China have successively explored asteroids,from the initial overflight,orbital detection to the subsequent landing,sampling and return.Asteroid detection technology is in the current society.Great progress has been made.Vigorously carrying out asteroid exploration missions can not only show a country's comprehensive strength to the international community,but also highlight a country's technological level and hard power in the field of aerospace.In this paper,Eros 433 is taken as the simulation object,and the guidance and control of small object detector during landing are discussed.Under the model-based system state equation,the guidance and control law is designed according to the task constraints.Firstly,the gravitational field modeling of asteroids is analyzed.Based on the spherical harmonic series method,the analytical expression of the three-axis gravitational acceleration in the asteroid fixed coordinate system is derived.The magnitude of the disturbance terms such as Eros 433 gravitational field modeling error,solar photopressure interference and third-body gravitational perturbation are analyzed.The dynamic equation in the asteroid fixed coordinate system is deduced,which provides a system model for the following guidance and control law design.Secondly,based on the multi-sliding mode guidance control method,the guidance control law is designed for the descent phase of the detector,and the simulation verification is carried out based on Eros 433 asteroid.Then,200 Monte Carlo simulations are carried out considering the initial error of the system state and the uncertainty of the external environment parameters.Based on the optimal performance index of fuel,the decimal ant colony algorithm is used to optimize the parameters of the guidance and control law designed at the same time.Finally,according to the nominal orbit guidance method,the control law is designed for the landing process of the detector,and the nominal orbit is established by using the cubic polynomial of time form.Considering the uncertainties of dynamic environment parameters and the initial state error of the system,the ADRC control method and sliding mode variable structure control method are designed to control and track the nominal orbit.Based on the Eros 433 asteroid,the nominal orbit is tracked.The simulation results show that the two control methods can track the nominal orbit in a limited time,and the residual landing speed of the detector is close to zero.