Study On Guidance And Optimizing Control Methods For Probe Soft Landing On Asteroids

Soft landing on the asteroids are the key issues mankind faces, exploration guidance and control technology is to achieve a soft landing surface of the asteroid key technologies. Though the summary of the present research in this field, we use the application of sliding mode variable structure guidance variables and trajectory tracking control method. In accordance with the vertical landing, landing speed is zero or within the acceptable limits and stability of the system task requirements, in view of the asteroid landing safety vertical soft landing guidance and control method, makes a deep research.First of all, the asteroid detector landing period of the dynamic action of the analysis, and define the relevant coordinate system. Due to the characteristics of the asteroid non spherical, the approximate for three axis ellipsoid, the ball harmonic series expansion method, established the asteroid’s second order gravitational potential function model. Then, it is assumed that the asteroid constant rotation, and consider the detector is the sun light pressure and the third body gravitational perturbation influence, respectively established the solid even coordinate system and the coordinate system of the 3 d orbital dynamics model.Secondly, designed of the detector segment declined guidance law, did the analysis of the detector dynamic characteristics of the landing environment. Consider the nonlinear characteristics of the fuel sub-optimal design nominal trajectory guidance polynomial method. We studied the features and applications of the sliding mode variable structure control of the subject. According to the control characteristics of declining period determined the use of non-singular Terminal synovial control methods in this article. Ensure the steady and rapid decline in the detector for landing.Finally, consider of the strong disturbance asteroid probe landing in the nonlinear systems, proposed a non-singular Terminal sliding mode control method based on RBF neural network. The influences caused by unknown disturbances and uncertainties during landing were compensated by RBF neural network real-time compensation, which could effectively suppress the influence of external disturbance and weaken the system chattering Ensure that the detector speed down to zero at the final moment motion. Achieve an optimal control for single-use of the non-singular Terminal sliding mode. Thus ensure the probe fast and accurate soft landing on asteroid surface.