ETS-IV on-orbit identification experiments (1st report, impulse excitation)

System parameter identification and attitude control experiments (FLEX) have been conducted as one of the bus experiments of Engineering Test Satellite-VI (ETS-VI) launched in August, 1994 by H-II rocket. The objectives of the identification experiment are to evaluate typical identification methods both in the frequency and time domains, to compare the identified parameters with the ones established in the ground test before launch and to construct the standards for designing attitude controller. This paper shows the results of the system parameter identification experiment using impulse excitation by gas jet thrusters for the attitude/orbital control system. Measurement data from attitude control system and paddle mounted accelerometers are down-linked by telemetry and analyzed by the Eigensystem Realization Algorithm (ERA) to identify flexible modal parameters.