Attitude control design of the M–V rocket

This paper deals with the design algorithm of the first–stage attitude control for the M–V launch vehicle, Japan's scientific satellite carrier. The control features enhanced and robust characteristics against a range of uncertainties of the system parameters. To achieve sufficiently robust characteristics, the problem is approached within the framework of the H∞ mixed sensitivity problem. The emphasis is put on how to apply the robust control theory to a complicated real problem. In the design, the standard process is modified in a special way. The original, unstable plant dynamics are preliminarily stabilized by a direct output feedback prior to using the standard design process. Then the standard theory is applied to these pre–stabilized plant dynamics to yield control. The final form of the controller is provided by its combination with the pre–specified feedback. This modification of the procedure is prompted by the fact that it is not always effective in unstable systems. Thus, the controller can be derived much more easily. The effectiveness of the design has been finally established by the first ever flight of the vehicle successfully putting the world's first radio astronomy satellite into orbit.