Hardware in the loop tests for upper stage control systems of Korean space launch vehicle

This paper concerns the development tests for the upper stage control systems of Korean Space Launch Vehicle. Hardware in the loop tests are accomplished for an engineering model of KSLV-I. The upper stage control system of KSLV-I consists of a navigation and guidance unit in which several inertial sensors and a guidance computer are included, a thrust vector control system which is used for pitch and yaw attitude control during thrusting phase, and a reaction control system which is used for three axis attitude control during coasting phase. The HIL tests of KSLV-I are basically accomplished for a nominal flight condition. Based upon the nominal flight condition, perturbed flight conditions are defined to evaluate the variations in stability and performance of the system. The HIL test equipments including a three axis flight motion simulator and a real time system are setup, and the coordinate systems which are required during the HIL tests are also defined. The typical angular motions of KSLV-I are given through several HIL test results.