Study On Navigation, Midcourse Correction And Attitude Control Of Launch Vehicle Upper Stage

Following the research and development of Chinese launch vehicle upper stage, for the purpose of engineering application, the trajectory errors caused by the instrument coefficients and the initial azimuth bias of SINS, SINS/Star sensor/Earth sensor integrated navigation technology, midcourse correction technology of transfer orbit and attitude control are studied in this paper.Considering the flight of upper stage in classical MEO transfer orbit described with launch inertial coordinate system, the inertial navigation solution equations are given out and the the errors propagation models are derived. The measurement error models of SINS are given out. A trajectory simulator of MEO transfer orbit is proposed by using the nominal trajectory data. The correctness of the inertial navigation solution equations is verified via the trajectory simulator. The trajectory errors are analyzed and a characteristical trajectory with errors is composed with some key instrument coefficients, which would be a basis for studying integrated navigation.For the integrated navigations system, a mathematical model of the visibility of GPS satellites and the availability of navigation signals is built. GPS navigation can be effective in the flight under the conditons of 3150 seconds afore or the height of less than 7740 km. On the contrary, the highest altitude of the trajectory is about 25000 km and the total flight time is 15800 s, which means the GPS navigation is not available within the most of the trajectory. Because attitude errors of SINS/GPS navigation and position errors and velocity errors of SINS/Star sensor are not accurate, a novel SINS/Star sensor/Earth sensor integrated navigation system is proposed. The observation equations are derived from attitude measurement model and the geocentric vector measurement model. The effectiveness of the novel SINS/CNS integrated navigation is verified by using the estimation errors obtained via Kalman filter and H filter.By the influence of non-spherical earth gravity, atmospheric drag, sun and moon gravity, solar radiation pressure and other perturbations, there are large errors between the real and the ideal transfer orbit. So the midcourse correction is studied. By the solution method of Lambert problem, the calculation method of correction velocity is derived. Considering the resourse of initial errors, an iterative algorithm with the error covariance matrix is designed, which has a superiority of small computation load and quickness compareing with the traditional calculation method of trajectory errors. Taking zero, one, two and three correction scheme as example, the choice of correction number is analyzed. The correction velocity impulse, the terminal position and velocity errors are contradictory through one correction result, which indicates that there needs to carry on a compromise. A two correction scheme is determined through multi-corrections. Then a multi-objective evolution algorithm is introduced to optimize the two correction timings. Tansforming the multi-objective optimization problem to a single objective optimization problem is a commonly used method, which can lose optimal solutions. So a modified non- dominated sorting genetic algorithm (NSGA-II) is introduced to the correction timing optimization problem, which obtains complete Pareto optimal solution set and increased flexibility of this optimization problem.Considering the model uncertainty and the liquid sloshing, a finite frequency domain H control algorithm is presented for the upper stage attitude control. The finite frequency omain H control not only has strong robustness for solving the uncertainty problem, but also has effective control ability in specific frequency range. Based on the generalized KYP lemma and its inference, Projection lemma, Reciprocal Projection lemma and linear matrix inequality knowledge, state feedback and output feedback controllers in finite frequency domain are designed. And to highlight the advantagesof finite frequency domain H control, design methods of state feedback and output feedback controllers in entire frequency domain are presented. The effeciveness and feasibility of finite frequency domain control are verified through the results of four examples with different model parameters and the availability of jet attitude control system.