Robust control and modeling a 2-DOF Inertial Stabilized Platform

Abstract

This paper presents an uncertain linear model for an Inertial Stabilization Platform (ISP). The system has a 2 degree of freedom (DOF) gimbal which will be attached to a moving vehicle and the optical sensors mounted on stabilized gimbal. The main purpose of an ISP is to eliminate the various disturbance and body motion to make the line of sight (LOS), hold steady in an inertial space. Due to dynamical model of the 2-DOF gimbal, friction, cable restraint, noise, other disturbances from the outside environment and the motions of the vehicle's body (as a result of maneuvering or vibration), the pointing and tracking accuracy of the gimbaled system may strongly degrade. These disturbances are typically nonlinear. Modeling and controlling the stabilization loop with these nonlinearities are the main problem. The approach of this paper is considering a linear doubted model. Linearity makes the model simple and so linear classic controller can be used to meeting design requirements. Therefore the cost of the design and implementation stages will decrease. In addition uncertainty makes the model practical and so the nonlinear nature of mentioned disturbance can be interpreted by this model. So this built ISP by a PI controller which is capable enough to overcome the disturbances and to meet the implication requirements will be controlled. For decreasing the effect of these uncertainties and other probable variation in ISP's parameters on system performance, a determined simple structure for robust enhancer compensator is used and designed.