Research On Station Keeping And Orbital Transfer Of Geostationary Satellites By Impulse And Electric Propulsion

The orbital position of geostationary satellites has become an increasingly scarce resource,however,demand for satellite users continues to grow.The traditional station keeping strategy results in a waste of orbital position resources to some extent,at the same time,the maturation of electric propulsion technology and its application on geostationary satellites also demand new control strategies.In this dissertation,the problem of space conservation control for geostationary satellites is systematically studied,and a better pulse location strategy and a new electric propulsion control strategy are proposed.Based on dynamic analysis,The mean orbital element extrapolation model and conversion method from osculating element to mean element of the geostationary satellite are studied and established.The periodic terms are separated from the perturbation equations of geostationary satellites based on dynamic analysis.A mean orbital element extrapolation model with long periodic perturbation term and long-term perturbation term is established,and the conversion equation of osculating element to mean element is derived on the basis of the short periodic perturbation term.The model and method can achieve efficient and high precision.A new calculation method of east-west station keeping problem of geostationary satellites with impulse thruster is established.Under the condition of full perturbation,the control of the geostationary satellite's east-west station keeping is difficult to be solved accurately and efficiently.In this dissertation,a new calculation method is designed and implemented according to dynamic analysis obtained by perturbation of long periodic perturbation term and long-term perturbation term.The problem of geostationary satellite's station keeping by electric propulsion is studied.An Optimization model overall considering orbit east-west and south-north control,and an Optimization solving method based on sequential quadratic programming was proposed.A method for the optimization of GEO satellites orbit transfer with all-electric propulsion is proposed.The Earth's oblateness(J2)perturbation is included in the dynamics.The optimal control law of GEO satellites as well as the first order optimality necessary conditions,based on Pontryagin's Maximum Principle(PMP),is deduced.The resulting two-point boundary value problem is solved based on thrust continuation approach and by means of a Newton's downhill method.Numerical simulations have demonstrated the effectiveness of the approach proposed,with performance about 5%improvement compared to the existing results.From the numerical results,some characteristics of the optimal transfer orbit elements changes are drawn,which could provide reference for aerospace engineering.To sum up,to station keeping problem of geostationary satellite,the orbit dynamics model,impulse control strategy and electric propulsion control strategy are studied in this dissertation,formed a set of relatively systematical geostationary satellite station keeping control method.Mean orbital element extrapolation model is universal and can be applied to other geostationary orbit control problems.The impulsive thrust control strategy and the electric propulsion control strategy have higher practical value,which can provide references for the improvement of the current pulse position control method and the design of the electric propulsion position control system.