Research Of The Guidance And The Landing Control Methods Of The Irregular Asteroid Probe

The main method of human being to explore the solar system and university is deep space exploration, which is also the foundation of observation, exploration and settlement of the solar system. Deep space exploration is divided into three categories:moon exploration, planet exploration and interstellar exploration. This paper seeks to study the guidance and control of planetary detector during the landing process.Firstly, the detectors’kinetic equation. The shape characteristics of irregular asteroid are taken into account, based on the relationship between the spherical harmonic coefficients and the gravitational potential energy, the order spherical harmonic coefficients of the asteroid’s gravitational field can be solved by using determined system of linear equations. This paper assumes that the velocity of asteroid’s rotation angular is uniformity, the detector is affected by the weak gravitational field of asteroid, but the effects of pressure of solar radiation and the gravitational perturbation of other planets are also taken into consideration.Secondly, aiming at the irregular shape, small size, weakness gravity of the asteroid, and the detector will also be affected by the pressure of the solar radiation and the gravitational perturbation of other asteroids during the landing process. This article designs the optimal sliding mode guidance and control law, which restraints the angular. The main purpose of optimal sliding mode guidance and control law, which combines the adopted proportional guidance law and sliding mode variable structure theory, is to control the speed and direction of velocity. When the detector affects by the sunlight in the system pressure and gravitational perturbation of other asteroids, this law can also ensure rate of detector’s sight angular decrease to zero, and eliminate the static shock of the rate of sight angular. The simulation of MATLAB shows that he optimal sliding mode guidance control law designed in this paper can ensure the rate of sight angular approaching to zero, when takes the fuel consumption of the detector and the gravitational perturbation of other asteroids into consideration.Finally, this paper chose the cubic polynomial method o design the expectation trajectory, in order to achieve the security of detector during the soft landing. The parameter optimization of sliding mode control is based on the optimization fuzzy parameter, which adjusts the switch gain to reach some goals. For ex example when outside the surface of sliding, the system could improve the time of response and overcome the pressure of sunlight and the gravitational perturbation of other asteroids. And when reach the surface of sliding, the system declines the control in order to eliminate chattering. The simulation of MATLAB shows that fuzzy optimization parameter of variable structure control method could improve the stability of the system effectively. This method could eliminate the chattering effectively, ensure the speedability of the approaching movement and avoid the disadvantages of traditional exponential reaching law, which switches the control surface frequently.