Solving The Pursuit-evasion Strategies Of Three Spacecrafts Based On Differential Game And Coevolution Algorithm

With the development of space science and technology,the pace of space exploration is getting faster and faster and the space competition has become more and more fierce at the same time.It is particularly important for the development of our country’s aerospace industry.Therefore,it is of great significance to study offensive and defensive confrontation issues in the space field.In particular,the game problem of spacecrafts with autonomous maneuverability is the future development trend.At present,most of the research is focused on the pursuit and evasion of two spacecrafts.However,the confrontation game between spacecraft is not limited to the two sides facing the increasingly complex space situatio.The pursuit and evasion strategy of spacecraft will be more complex and flexible in the actual application of confrontation.Therefore,the problem of multiple spacecrafts pursuit and evasion confrontation is studied in this thesis.In this thesis,the spacecraft is processed as a mass point,regardless of the attitude of the spacecraft.Aiming at the pursuit-evasion problem between two spacecraft under continuous low thrust,a virtual reference star is introduced to establish a relative motion reference coordinate system,and the relative motion of spacecraft is deduced.The pursuit-evasion problem of spacecrafts is actually a continuous confrontation problem formed by two or more parties through autonomous control,and the differential game is just a continuous dynamic game.This paper has established the spacecraft pursuit and evasion schemes of "one-to-one","two pursuit and one evasion","one pursuit,two evasion" and "one pursuit,one evasion and one defense" based on the theory of differential games,then designs mumerical solution scheme using co-evolutionary algorithm,and carries out simulation analysis of numerical examples.By the comparison of sumulation results of different numerical examples,it is shown that the "two pursuit and one evasion" mode makes the interception effect of the pursuit spacecrafts more excellent,and one of the pursuit spacecraft which fails to intercept the target alone plays an important role in this scheme,which improves the overall interception efficiency.The pursuit spacecraft needs to make a maneuver for the two maneuvering strategies of pursuit spacecrafts,which reduces its pursuit efficiency.In the case of the "one pursuit and two evasion",the chasing maneuver strategy is interfered by two pursuit spacecrafts thus the pursuit efficiency is reduced and evation spacecrafts cannot be intercepted within a certain period of the time.However,when the one of evation spacecrafts is at a relatively disadvantaged position,it will be intercepted successfully.In the case of “one chase,one escape and one defense”,a defensive spacecraft is added to protect the evation spacecraft,when the pursuit spacecraft chases the evation spacecraft,the defensive spacecraft will antiintercept it.Therefore,the pursuer needs to consider the interception strategy of the defensive spacecraft,which affects its interception effect.In addition,a closed-loop three spacecrafts chasing scheme was designed.Because they are in a state of mutual influence for a certain period of the time,none of them can successfully intercept each other.A comparative analysis of these four pursuit methods has verified the feasibility of the method.The pursuit-evasion strategies of three spacecrafts proposed have practical significance for space offensive and defensive confrontation.