Sliding mode control based line-of-sight (LOS) stabilization of electro-optical sighting system

Abstract

Electro-optical sighting systems are used for surveillance, target acquisition and tracking. The stabilization of the line of sight (LOS) against vehicle-induced disturbances is an essential feature of the electro-optical gimbaled sighting systems, mounted on mobile platforms. Due to factors like host platform dynamics, friction, cable restraint and noise, the pointing and tracking accuracy of the gimbaled system degrades substantially. This work presents control law design for LOS stabilization of a gimbaled electro-optical sighting system, using sliding mode controller (SMC). Other controllers like proportional-integral (PI) controller (conventional frequency domain approach) and linear quadratic gaussian with loop transfer recovery (LQG/LTR) controller (state-space based optimal control) are also compared with SMC for such application. SMC is a non-linear controller that is modified in this work which further reduces the chatter so as to achieve better steady state accuracy. All these controllers meet the stringent requirements of disturbance attenuation and command following.