Robust stabilization loop design for gimbaled electro-optical imaging system

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. keywords: LQG/LTR, robust multivariable control, line-of-sight stabilization, multi-axis gimbal, loop shaping