Scan loop control design for a spin-stabilised seeker

A scan loop model for a spin-stabilised seeker is introduced, which includes gyrodynamics with direct- and cross-spring constants for considering the autoerection effect of the gyro. The LQG/LTR and H∞ controllers are designed for the seeker scan loop system which has model uncertainty and is subject to external disturbances. The performance of LQG/LTR controller can be improved by obtaining uniform singular values over all frequencies for the target feedback loop. The H∞ controller is designed in the framework of the standard H∞ optimisation problem with model matching. The proposed H∞ method can reflect not only frequency domain specifications but also time domain ones, such as transient response characteristics and multivariable interaction between output channels, differently from the mixed sensitivity problem. It is shown that the designed LQG/LTR and H∞ controllers offer good performance and robustness properties, and both controllers are very effective in the seeker scan loop system.