Extended-State-Observer-Based Output Feedback Sliding Mode Control of Inertial Stabilized Platform

Inertial stabilized platforms are extensively utilized to achieve high-precision pointing of optical axis in spite of vehicle motion or vibration. This paper develops an output feedback sliding mode control strategy for the inertial stabilized platform. The dynamic model taking into account various disturbed phenomena is established first. Not only the unknown state but also the lumped uncertainty is effectively estimated by extended state observer and brought into the sliding mode controller design. With the Lyapunov function technique, the tracking error of the inertial angular rate is verified to converge to an arbitrarily small region by adjusting certain control parameters. Furthermore, the switching gain is only required to he chosen to restrain the uncertainty caused by states estimation errors rather than disturbance itself, which substantially alleviates the chattering phenomenon. Comparative simulations are presented to show the effectiveness of the proposed method in two typical operation mode.