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. 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 the 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 response characteristics and multi-variable 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