Study On The Collision Risk Assessment And Security Control Of Satellite Formation Flying

Satellite formation flying is a forward direction in the development of space technology, and the problem of collision avoidance concerned with formation is becoming an important issue.In this paper, the main work included the following four aspects.Based on the relative E/I vector, this paper established dynamical models describing the relative motion between the satellites in the formation, through which the analysis of the configuration changes in the case of J2 perturbation were carried out.Based on the dynamical models with relative E/I vector, the propagation of the initial navigation error was analyzed.Compared with former method, this method was more concise and intuitive. By the addition of J2 perturbation, the accuracy is improved, and the prediction of the error covariance matrix over long time is more accurate. The collision risk assessment based on the integral of collision probability was completed, providing a criterion for the forecast of the collision and the maneuver plan.As for the avoidance of space debris, the short-term and the mid-term avoidance strategy were discussed. For the short-term avoidance, this paper put forward a new method based on the descent in the negative-gradient direction of the probability density function. This method enables the position shift in the negative-gradient direction of the probability density function on the certain time. A new optimization method based on the error correction was proposed for the influence of the error. The feasibility of the method was verified by simulation analysis.An effective control method for the collision avoidance between satellites was proposed. First, the target is set to the collision region of the bulk of ellipsoid. Then guide the satellite to get out of this region through certain pulse. However, in case of the transformation of formation configuration, the rate of along-track drift in the final time must be limited. Next the distance in the plane vertical to the along-track direction should be guaranteed for safety. Ultimately, with these constrains, the maneuver plan was optimized for the least fuel consumption target.