Research On Simulation Of The Motion Of Landing And Hopping Of Asteroid Hopping Probe

Asteroid exploration is of great significance to the exploration of the history andevolution of the universe and the origin of life, the exploration of space resources andprobing deep space environment as well as preventing the threat of near-Earth asteroids.The ideal way to conduct a detailed probe of the asteroid research is the use of landingprobe for in-situ exploration. For asteroids’ special microgravity environment, hoppingprobe can solve the problem of moving under microgravity environment thus ideal forin-situ asteroid exploration. This thesis is mainly focus on dynamics modelling of thehopping probe during its hopping and factors that influence the motion of probe duringits landing and hopping, the main work of this thesis is as following:With the introduction of instantaneous collision model,2D dynamics model of thehopping probe during its hopping is established based on instantaneous collision modeland kinetic equations are derived.2D and3D dynamics model of the hopping probe areestablished based on continuous contact force model.Comparison between2D dynamics models based on instantaneous collision modeland continuous contact force model is presented by comparing results of the two models,which verify the reasonableness of the two models. Analysis about the big differencebetween the results of two models in some cases is presented, which shows that themain reason is the irrationality of the use of Newton’s coefficient of restitution inoblique collision.Analysis of the main factors that influence the motion of the probe during itslanding and hopping is presented, which shows that the main factors include: coefficientof restitution, coefficient of friction, stiffness of the ground, gravity, initial velocity ofcenter of mass, initial angular velocity. Through analysis of the influence of the factors,we come to the conclusion:The coefficient of restitution has relatively big influence on the result of simulation,thus extra attention should be paid to it in dynamics modelling.The influence of stiffness of the ground for the result of simulation is relativelysmall, but in the long term, it has some certain impact on the motion of the probe duringits landing and hopping. Thus, it is appropriate to relax the requirements for theaccuracy of the stiffness coefficient under the condition that the requirement for theaccuracy is not very high or the simulation time is not very long.Gravity of the asteroid is a vital factor that influence the motion of the probe, thusprecise understanding of asteroid’s gravity as much as possible is needed. The gravity ofasteroids of different sizes and different types will be very different, so, more accurate gravitational field model is needed in the dynamics modelling of the hopping probe.Coefficient of friction is also an important factor that influence the motion of theprobe thus precise understanding of asteroid’s coefficient of friction as much as possibleis needed. And rough ground is not good for the probe’s landing.The initial velocity of center of mass has a great influence on the motion of probeduring its landing and hopping. The influence of vertical component of the velocity ofcenter of mass is most significant among the three directions components. The XOYplane component of velocity of center of mass has a decisive influence on the hoppingdirection on XOY plane and the position of stop location relative to the landing point.From the view of the requirements of hopping probe’s landing on asteroid, there isobvious need to minimize the initial speed of the probe during its landing, so as tominimize the time of hopping process and the distance between the stop location andthe scheduled landing position.The initial angular velocity of the hopping probe is also a relatively importantfactor that influences the process of probe’s landing and hopping on asteroid. But itsinfluence is not so apparent compared to velocity of center of mass, and the influence ofvertical component of is weaker compared to the other directions. Therefore, in theprocess of landing and hopping, the requirements of initial angular velocity arerelatively lax, it does not need to be strictly controlled within a very small range, but itneed to be as small as possible in order to make the hopping probe stop as soon aspossible after landing on the surface of asteroid.