A robust design approach was proposed to address the line-of-sight (LOS) control problem for a gimbaled seeker with yaw-pitch configuration. Differential equations on LOS dynamics were deduced via the moment balance of each gimbal. The different modes in which the major disturbances, including disturbance torque, system nonlinearity and platform angular motion, influence the system dynamics were analyzed. Based on the unstructured uncertainty descriptions of the system, a H∞ controller was synthesized to realize servo control on the LOS attitudes. Simulation results demonstrate that the proposed approach supplies strong robustness against system uncertainties, disturbance torques and nonlinearities.

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