  For electro-optical imaging systems, line-of-sight stabilization against
different disturbances created by mobile platforms is crucial property. The
development of high resolution sensors and the demand in increased operating
distances have recently increased the expectations from stabilization loops.
For that reason, higher gains and larger bandwidths become necessary. As the
stabilization loop satisfies these requirements for good disturbance
attenuation, it must also satisfy sufficient loop stability. In gimbaled
imaging systems, the main difficulties in satisfying sufficient loop stability
are structural resonances and model uncertainties. Therefore, satisfying high
stabilization performance in the presence of model uncertainties or modeling
errors requires utilization of robust control methods. In this paper, robust
LQG/LTR controller design is described for a two-axis gimbal. First, the
classical LQG/LTR method is modified such that it becomes very powerful loop
shaping method. Next, using this method, controller is synthesized. Robust
stability and robust performance of stabilization loop is investigated by using
singular value tests. The report is concluded with the experimental validation
of the designed robust controller.
