Study Of Semi-Physical Simulation Theory And Its Experimentation Method Of Spacecraft Attitude

The semi-physical simulation theory and its experimentation means of spacecraftattitude is one of important content of research on spacecraft attitude simulationtheory, which can realizes simulation of attitude and assessment of systemperformance. At the same time, assessing the credibility of system simulation roundlyand correctly is the footstone of assuring that system simulation has better reliability,so studying credibility of system simulation is very necessary. Based on semi-physicalsimulation system of spacecraft attitude, two important problems on semi-physicalsimulation theory and its experimentation means of spacecraft re-entry and on-orbitattitude and its credibility research have been done.First, the research situation and development of national and internationalsimulation is analyzed. Especially, for the different characteristic of semi-physicalsimulation of spacecraft re-entry and on-orbit attitude, the status of tri-axis air-dearingtesbeds and tri-axis servo simulator are discussed. The significance of analogous andcredibility theory and its influence on the simulation, especially on semi-physicalsimulation of spacecraft attitude are summarized. And theory and the developmentdirection of slide mode control are summed up.Second, Based on the mathematical model of spacecraft re-entry and on-orbitattitude dynamics and the characteristic of the air-bearing testbeds, the state equationsof semi-physical simulation system are presented.Fundamental theory of analogous has been studied by the numbers, and themodel analogous rule and reduced scale restriction expression are deduced forsemi-physical simulation system based on the model reduced scale, which are regardas theoretical foundation for the design of semi-physical simulation system anddirection of model examination. By investigation of the credibility validation methodof the simulation system, the common method of conformation of credibilityevaluation index model, confirmation of weight vector and calculation of simulationcredibility is given. Finally the quantificational calculation relation of credibility andconfidence level is given based on examination statistics theory.Every part and its main function of spacecraft on-orbit attitude semi-physicalsimulation system are narrated, the characteristic and examination method and principle of which are studied based on similarity theory. The selection principles ofthe reduced scale of the spacecraft simulation system on ground are given, and thevalidity of the model analogous rule has been validated. At the same time, toovercome the noise disturbance and the influence of non-ideal factors, the slide modecontroller(SMC) of the air-bearing simulation system is designed based on DDFC(direct dynamics feedback compensation).Finally, to illuminate issue, as spacecraft antenna pointing semi-physicalsimulation system for example, combining the front analogous and credibility theory,some problems met during development of the system are discussed, and then theerror model is given by analysis, and credibility assessing are studied, the credibilityof this system is demonstrated, the result show that this system has relatively highcredibility, can satisfy the request for simulation.By investigation of attitude and moment of inertia measure method, newmethods of attitude angle and moment of inertia measure are given, its balancedemarcating method is given too. This method is simple and practicable. In addition,the calculating method of gravity moment of the tri-axis air bearing is given too.Pointing to such characteristic of spacecraft re-entry attitude simulationexperimentation system as rapid-time-variability, exquisite and large parametervariability scope, several key problem of the experimentation method are discussed,for instance, the rudder loop module, aerodynamic moment simulation module andcircumstance disturbance simulation module and so on. At the same time, to removethe influence of the earth rotation, the kinematics equation of the servo inertia test-bedis calculated. And to overcome the noise disturbance and the influence of non-idealfactors, the double loop slide mode controller(SMC) of the spacecraft re-entry attitudesimulation experimentation system is designed based on time scale abruption, andsimulation has been done. Finally the credibility of simulation is improved too.In conclusion, this paper is organized on the practice request of the spacecraftre-entry and on-orbit attitude semi-physical simulation system scheme, It was wishedthat this work had some reference significance for simulation project practice andfurther research.