Research On Independent Survival Collision Avoidance Technology Of Satellite Clusters

With the accelerating process of human exploration of the vast universe,the complexity of space mission is also increasing.It has become a hot spot in the field of aerospace to complete the on-orbit mission with the close range of satellite clusters.Due to the complexity and long mission period of the space mission in orbit,the maneuverability of a single satellite or numerous satellite cannot be satisfied very well.Once the concept of satellite clusters is put forward,it is widely concerned and researched by researchers and experts in various aerospace fields at home and abroad,and has become the research focus of national defense and aerospace scientific missions.Different from the traditional satellite formation,the satellite clusters has the quick response mission,high flexibility,rapid reconfiguration of on orbit configuration and strong autonomous survivability.It can maintain long-term autonomous operation in orbit and the member stars stay in a specific space area,which does not limit the relative position and distance between the member stars,nor need to maintain a fixed configuration of space.Therefore,the satellite clusters needs to have the autonomous survival ability such as long-term autonomous orbit optimization,long-term autonomous orbit maintenance,long-term autonomous collision avoidance,long-term autonomous fault handling and life optimization.Based on the above-mentioned on-orbit security issues,autonomous survival technology of satellite clusters is proposed.In this research background,the main content of this paper is composed of the following aspects:The definition and transformation of the space coordinate system are used to establish and describe the dynamic model of the relative motion of the satellite clusters,and the relative motion between the member stars and the estimation of the temporal interval of possible collision are studied.Firstly,the relevant coordinate systems are selected and defined,and the transformation of each coordinate system of the satellite clusters is described in detail.Since the corresponding state of the satellite clusters on-orbit needs to be determined using six parameters,the orbital element of member satellites are described.The relative motion state of each member satellite on-orbit is modeled and analyzed,and the relative dynamic models and equations of the member satellites of the satellite clusters on-orbit are given.The relative motion of each member satellite is described,and the position and velocity expressions of the relative motion between member satellites are given.The possible temporal interval of collision between member satellites are estimated as the basis for collision probability calculation and maneuver avoidance.In order to solve the problem autonomous operation safety of satellite clusters on-orbit,the possible collision of member satellites with uncertain position is studied.Firstly,the model of the encounters of enveloping ellipsoids between member satellites is established in the region where the collision may occur,and the mathematical description of the model is given.Using the ellipsoid probability density function of spatial position error to calculate the collision probability,the normal distribution probability density function(PDF)of each time corresponding position error vector falling in the three-dimensional space of the closed envelope sphere is obtained,and can get the probability of collision at each moment when member satellite is likely to collide.Finally,in order to simplify the calculation of the collision probability,the dimension reduction is carried out to improve the efficiency of the calculation of collision probability of each member satellite on-orbit.Due to the possible collision of satellite clusters on-orbit,based on the description of the relative states of member satellites on-orbit above,the member satellites in the possible collision area are evaded.The calculation results and analysis of the collision probability of the satellite clusters of three and five member satellites,as well as the results and analysis of the avoidance strategy are given.Firstly,a collision avoidance strategy based on relative distance is proposed for the close range operation of the satellite clusters.The fastest changing direction of the velocity of the member satellites on-orbit is obtained by the determination of the gradient direction of the collision probability density distribution.The collision maneuver avoidance speed is obtained by the analysis of the relative state information of the member satellites,and the possible collision of the member satellites are estimated and avoided.According to the different missions and scale uncertainty of the satellite clusters on-orbit.The collision probability of the satellite clusters with the scale of three and five satellites are calculated and the member satellites that may produce the collision temporal interval are maneuvered to avoid.The effectiveness of the maneuvered avoidance strategy is verified by simulation.