Autopilot design for a tail-controlled missile using two-degree-of-freedom controllers

Abstract

The purpose of this paper is to highlight the digerences in frequency and time responses between one(I-DOF) and two-degree-of-freedom (2-DOF) systems in the design of a missile autopilot. Several designs are perforined using H 2 optimization on a tailcontrolled missile which is nonminimum phase with lightly dumped poles. The frequency responses show that the 2-DOF system exhibits more Jlexibility in being able to meet all of the performance criteria due to the fact that it has one compensator dedicated to planf disturbance and measurement noise rejection and one dedicated to command following. The time responses indicate that the tracking ability of 1-DOF systems is mostly dependent upon the assumed level of the plant disturbance, while 2-DOF systems are concerned primarily with the relative magnitudes of assumedplant disturbance to assumed measurement noise. If the ratio of assumed values is correctly chosen, then the 2-DOF system achieves better tracking performance than the iDOFsystem, no matter what values are assumed for the