CONSTRAINED STATION CHANGE IN GEO USING A LEGENDRE PSEUDO-SPECTRAL METHOD

摘要

The algorithm for numerical approximation of the optimal control is formulatedusing a Legendre pseudo-spectral method to solve the problem of constrainedstation change in GEO. A collision avoidance term, which is includedin the objective function as an integral form, is considered during transfer byspecifying a maximum or minimum radius depending on whether the transferis in the east or west-direction. Several east-and-west-direction station changetransfer maneuvers are simulated; the histories of the states and control behaviorare obtained and all the variables are found to be within feasible ranges.Multiple revolutions and large longitude station change cases are also demonstratedusing this method. The transfer time is found to be only weakly affectedby the initial thrust acceleration for the multi-revolution change cases.This method would be possible to implement using very low-thrust engines, inparticular, by employing attitude control thrusters.