Approaches for the Spacecraft Security Defense and Evasion Maneuver Method

Author:Yu Da Teng

Supervisor:zhou jian ping wang hua


Degree Year:2017





In the future war,the one who has the space mastery will master the battlefield initiative.Therefore the safety of spacecraft is becoming more and more important.The evasive strategy is one of the core contents in the space safety problem.The present space evasive research generally chooses space debris and failure spacecraft as study objects.However,the present evasive method will be useless when doing with the threat of the spacecraft of capturing and kinetic kill vehicle.In this paper,this kind of problems are divided into two threat styles—low speed approaching and high speed approaching,and the safety analysis model and evasive strategy are respectively designed.The main results achieved in this dissertation are summarized as follows:A safety analysis model used for spacecraft is built.In the paper,the safety analysis model used for defensing the spacecraft of capturing is proposed.The impulse,rendezvous time and minimum relative distance are chosen as three safety analysis index.The three safety analysis indexes are normalized,and the calculating method for the weightings of the three safety analysis index are given.Thus,a multi-index weighted comprehensive evaluation model is built to integrate the three safety analysis indexes.The study proposes an optimal method for the safety analysis when spacecraft is threatened by the spacecraft of capturing.A ne w evasive maneuver method with ene rgy game considered is proposed.A multi-impulse rendezvous optimization model is built based on the sequential quadratic programming(SQP)algorithm with energy game considered.Then the definition and computing method of potential threatening area are proposed.The target evasive optimization model is established by using Genetic Algorithm(GA),and the potential threatening area is set as optimization target.The numerical results verify the validity of models in the paper.The simulation results show that the double optimization model based on SQP and GA can effectively decrease the length of potential threatening area when the target evades by a fixed impulse.In the view of energy game,the proposed approach offers a novel effective evasive strategy in solving orbital evasion problem and can improve the viability of the target.A ne w evasive maneuver method with measure game considered is proposed.A bearing-only relative navigation model is built and the definition of absolutely non-observable maneuver is proposed.After some algebra,it is proved that the absolutely non-observable maneuver is non-existent.Based on that,an object function using vector multiplication is designed to find the minimum of measurement difference during the evasion.Then,optimization model is established and the variable bound is given,so the minimum of the object function can be obtained by Genetic Algorithm.The simulation results show that the method proposed can improve the state estimated difficulty of the chaser and reduce the estimated accuracy.In the view of measuring game,the method offers a new evasive strategy for the target and can provide a useful reference for the evasive research that choose the noncooperative chaser as research object.A final phase attack area modeling method of Kinetic Kill Vehicle(KKV)and an optimal evasive strategy of the target is proposed.Based on the analysis of space geometry,the projection of maneuvering range of both KKV and target in the attack area is calculated.Based on the established mode l,the calculating methods of capture region,escape region and barrier are derived and the explicit formulation is obtained.Fuel consumption is introduced as a condition of energy constraint.Thus,the attack area calculating model is established with energy constraint.According to the attack area model,the optimal evasive strategy is obtained through the analysis of attack area and projection calculation.The simulation results show the effectiveness of model,projection calculation and optimal evasive strategy.Using the opposed model,the capture and escape region can be calculated in a convenient way.A new decoy releasing strategy used for anti-ene rgy interception is proposed.Based on the analysis of guidance process in the terminal-course interception,a new decoy releasing strategy is proposed which can max the effect of the decoy and improve the survival rate of the target.Considering with the definition of the seeker and the blind zone of the guidance,the analytic expression of the decoy releasing time is obtained.Then,the maximum miss-distance explicit computing expression is derived.The simulation results verify the correctness of the maximum miss-distance computing expression and show that the terminal miss-distance has a close relationship with the dpi of seeker,initial relative distance and the acceleration.The decoy releasing strategy proposed is an effective method to defense KKV and has a potential for industrial application.In the space safety problem,the spacecraft of capturing and kinetic kill vehicle are two threats those are very hard to evade.For those evasive problems,effective efforts are made to explore some new evasive strategies in this dissertation.The safety analysis model and evasive strategies those have different focuses are proposed.The achievements obtained in this dissertation can serve as theoretical support to the future space safety in the industrial application.Moreover,it will also greatly improve the spacecraft survivability of our country.