Institute of Space and Aeroautical Science University of Tokyo
Institute of Space and Aeroautical Science University of Tokyo
Institute of Space and Aeroautical Science University of Tokyo
At the present launch of the satellite, only the attitude of the final stage motor is controlled to the predetermined direction, and attained orbit of the satellite may differ from the nominal value because of the disturbances suffered before. Since these disturbances can be known by a real time tracking radar, there are some possibilities to improve the accuracy of the orbit by controlling the final motor according to that information. At present, the final motor is injected to the local horizontal direction at the apogee point of the preceding suborbit and there are considerably a lot of time for the vehicle to reach the apogee. Therefore, it is possible to estimate the suborbital parameters, solve the optimum control law for the final motor and command these results to the vehicle before the injection, and the radio guidance system is realized with relatively simple software and hardware. In this paper, the basic concepts and criterion of the guidance system are discussed from a practical viewpoint, and the algorithm are obtained to get the optimum direction and ignition time for the motor that optimize the orbit of the satellite on the condition that the preceding suborbit is estimated with sufficient accuracy. The adaptability of the algorithm for practical experiments is assured by the numerical examples applied to some typical flight test data previously obtained.