Discrete sliding mode control of seeker scan loop using adaptive reaching law

This paper presents a discrete sliding mode control (DSMC) for seeker system, which consists of two axes gimbal system and an infrared sensor. The main objective of the discrete controller is to compensate the parametric uncertainties and disturbance due to cross-coupling torque between the two gimbals. A DSMC is designed using adaptive reaching law. A spiral scan loop is generated using a sinusoid and a cosinusoid waveform of varying amplitude and the seeker is made to follow this spiral pattern for searching. Su´s disturbance estimator is used to compensate total lumped matched disturbance. The performance of the controller is validated in simulations.