Research On Trajectory Optimization And Guidance Algorithm Of Orbital Transfer Vehicle

As the requirement of space on-orbit servicing mission has improved, orbit transfer vehicle has been concerned by more and more people as one kind of realization which can save fuels and easy to use. This is a system engineering which involved many subjects, such as the structure design,modeling analysis, flight trajectory optimization,navigation algorithm and guidance technology of spacecraft. This thesis covers several important techniques in the branches above, and its research results are summarized as follows:Aimed at the flight features and mission requirements of orbital transfer vehicle,dynamic modeling is completed for the earth orbit transfer mission and interplanetary exploration mission. 2-body dynamical model of inertial coordinate system,C-W and its improvedmodel of LVLH coordinate system, modified orbit element of guass coordinate system and the ADBARV dynamic model are applied to the flight phase above.Through the modeling process above the dynamic process of orbital transfer vehicle in and out of the planetary atmosphere can be describe unified.Polynomial direct method is used to solve the optimal trajectory. Concered the continuous low thrust and speed impulse realization, optimal trajectory is solved for the orbital interception, transfer problem and the close rendezvous problem. The psedospectral method is used to solve the aero-assisted orbital transfer problem and the aero-gravity assist orbital maneuver problem when OTV serve for the interplanetary exploration mission for the first time, through the comparison of fuel cosumption of this method and the traditional transfer method, the fuel saving fact of aero-assist approach is proved. Aimed at the change of orbit plane, the restriction of heat-rate amplitude, the maximum and the minimum of heliocentric velocity, the change of trajectories are given. For the continuous low-thrust many revolution orbit transfer problem, the psedospectral method is used to get the optimal trajectory with different thrust limit values, and the comparison of simulation result is given, Relationship of Thrust limit and transfer time is given.A MAE Predictor-corrector with feedback linearization method is used to settle the guidance problem of OTV, aimed at that when concern terminal constraint only the optimization process can not be be completed, guidance cycle is divided into several phase and the terminal state of every phase is trated as the optimization value, through this approch the guidance trajectory can follow the nominal trajectory perfectly and the consumption of velocity is reduced. According to the rapid optimization speed and high precision of psedospectral method, a psedospectral feedback guidance strategy is used to achieve the guidance process of aero-gravity assist problem, the simulation result show that guidance trajectory has a strong robustness, and the optimization time of every guidance cycles can be limit to a given range. Using the method of preserve time margin the trajectory deviation prblem caused by optimization time can be solved. The result shows that using variable distance nodes can improved the disturbance rejection effect and guidance performance.Using differential algebra method,first aimed at the speed pulse condition, shooting method is used to solve the Lambert problem of orbit transfer and interception process, and the nomial optim-pulse value is obtained. To correct the trajectory deviation caused by initial position and initial ignition time error, differential algebra method is used to get the correction speed value and the continus acceleration value. Though this method the deviation of real trajectory with nomial trajectory caused by the effect of initial error can be solved, and the terminal position precision meet the requirement.In conclusion, by analyzing and simualtion, this thesis make process on the problem of dynamic modeling, trajectory optimization and guidance strategy of OTV, and proposed some methods on solving this kind of problem. Which maybe provides ideas for the research on formation flying, orbital interception and reentry fields.