Research On Contorl Problems Of Separation And Departure Phase Of Spacecraft Rendezvous And Docking

Manned space flight technology has been the research focus in the world aerospace field, and spacecraft autonomous Rendezvous and Docking (RVD) plays a key role in the manned space flight technology. Almost all of the manned space flight engineering requires autonomous RVD, such as on-orbit-serving, space maintenance and rescue and material supply for space station. The research of RVD is also very significant in our country since space station project and lunar probe project are being carried out.The main work of this thesis is to study orbit maneuver control problems of the separation and departure phase of spacecraft autonomous RVD. Based on established departure dynamics model and different design objective, this thesis has designed limited thrust guaranteed cost control law and limited thrust H∞control law. The main results are as follows:Firstly, dynamics model for the departure phase of RVD is induced. At the beginning, the procedure of departure phase is described in detail. Based on the two body problem, the relative motion equations are established, named C-W equation. Then based on C-W equations, free motion of chaser spacecraft is investigated after unlocking and departure. Furthermore, some constraints during the departure procedure are introduced.Secondly, limited thrust guaranteed cost control law is designed. A new state error model is established, which converts the constant tracking problem into asymptotic stability problem with state feedback control law. Limited thrust controller is obtained which minimizes the upper bound of quadratic performance index. Fuel consumption is compared among V-bar departure, R-bar departure and H-bar departure. Simulations are conducted for fly-around from R-bar and H-bar holding points to V-bar holding points.Finally, limited thrust H∞controller is designed. Another new model is established which converts the constant reference tracking problem into asymptotic stability problem of the augmented system with state feedback control law. Taking quadratic performance index as H∞performance output, limited thrust controller is designed which minimizes the H∞performance index. Then limited thrust guaranteed cost law and limited thrust H∞control law is compared by simulation. Comparison is carried out regarding the effect of thrust upper bounds to H∞performance index. At last, fly-around form R-bar and H-bar holding points to V-bar holding points is simulated.