On The Calculation Of The Collision Probability Of Spacecrafts On The Low Earth Ciecular Orbit And Its Avoiding Strategies

With the rapid development of human space technology, space activities are constantly increasing, the number of space spacecraft in near-Earth orbit is also rising sharply, and the space around the earth becomes more and more crowded. Flying in such a crowded environment, the collision probability between spacecraft and space debris is significantly improved, so the study of collision warning and avoidance maneuvering strategy is significant. In this paper, we regard the relative motion between spacecraft and space objects as non- linear movement, starting from the general form of the relative position error covariance matrix, calculate the collision probability, then analyze the confidence of the collision probability, finally study the avoidance maneuvering strategy.The collision warning and avoidance maneuver of spacecraft are the analysis of relative motion. In the first chapter, the research progresses and statuses of spacecraft collision warning and avoidance maneuver strategy are introduced. The second chapter introduces and explains the basic knowledge used in the process of solving problems, derives the kinetic equations of relative motion between spacecraft and space objects, and predicts the future state according to the initial relative status. K nowing the relative status, collision probability model is constructed basing on the relative status in the third chapter, then applies the maximum instantaneous collision probability and pseudo maximum instantaneous collision probability to describe the possibility of collision. After that makes an analysis of error propagation characteristics and proposes the concept of false alarm rate. With minimum energy consumption criterion, the chapter four discusses the avoidance maneuver strategy under the premise of meeting the collision probability constraint. When searching for the optimal maneuver strategy, we firstly discrete the continuous optimal control problem using the control vector parameterization method and the collocation method, and then find the optimal strategies for the two methods separately, finally compare and analyze the results of the two methods.By analyzing the simulation results, it can be obtained: while the relative velocity of spacecraft and space objects is small and the relative motion is non- linear motion, the pseudo maximum instantaneous collision probability is capable of describing the possibility of collision and can greatly reduce computation time; the collision warning of spacecraft and space objects takes the forecast expectation and distribution into account, due to the error of the measuring system, a given interval of collision probability can better describe the he probability of collision; while the spacecraft maneuvers to avoid the collision, considering the premise of meeting the collision probability constraints, the control vector parameterization method is much more reasonable and convenient than the collocation method.