Hamid Javanmardi - School of Electrical and Computer Engineering, Shiraz University, Shiraz, Iran
Mohammad Zohrei - Department of Electrical and Electronic Engineering, Shiraz University of Technology, Shiraz ۷۱۵۵۷-۱۳۸۷۶, Iran

For decades in the aerospace and control sciences, the Inertial Stabilized Platform (ISP) system has been studied to improve the accuracy of recipient photos or target tracking. This paper presents a nonlinear observer-based control method for three Degrees Of Freedom (۳-DOF) ISP systems. First, a new formula of the state space equation for the ۳-DOF ISP system is proposed to make this model suitable for designing an observer-based control. Then, by measuring the angular positions as output feedback, the angular velocities are estimated by the nonlinear observer, and Lyapunov-based nonlinear control techniques are used to design the observer. Furthermore, the exponential stability and convergence of the observer system are proved. Finally, the auxiliary control signal is considered so that the dynamics of the designed observer become a simple linear form and are easily controlled by the state feedback controller. Simulation results illustrate the effectiveness and feasibility of the proposed control strategy.

Exponential stability, Inertial Stable Platform, Lyapunov techniques, Observer-based control, State feedback controller