Inertial stabilized platforms (ISP) are used in many acquisition, tracking and pointing systems, in which the line of sight (LOS) of electro-optical sensors must be kept steady. This is very challenging, especially in long range Electro- Optical/Infrared (EO/IR) systems where the LOS is more sensitive to mechanical-electrical noise, aerodynamic force or base motion effects. The efforts to improve the stability of the system includes various approaches from control algorithms, feedback/feed forward compensator to dual-stage controller or six degrees of freedom pivot, etc. n this paper, the authors present several control architectures for a multi-axis ISP system. First, the dynamic of four-axis gimbaled pedestal is modeled taking into account the effects of friction, cross-coupling and mechanical limitation. Then, the control loops for stabilization and pointing are designed using master–slave architecture for each gimbal axis. The pointing accuracy and stabilization level are analyzed and evaluated by simulation and experiment. At the end, by switching the role of each gimbal, an optimal control architecture that performs the stabilization at micro radian level in the wide range of bandwidth has been suggested. It is also proved that the proposed methods are effective for other EO/IR mobile systems that suffered various frequency of disturbance.
The stabilization of the Line of Sight (LOS) of an Electro-Optical System (EOS) locating on a moving platform contributes significantly to the image quality. A portion of perturbation inherited by the base motion can be eliminated by numbers of algorithms with powerful processors boards. However, it is difficult to implement these algorithms in embedded systems because of memory capacity and processing speed limitation. This paper introduces a method for identifying gimbal parameters and feedforward compensators. The key parameters including the friction force, cross-coupling effect and misalignment compensator are investigated using feedforward compensator theory and verified by practical experiments. The effectiveness in the stabilization loop is validated through many scenarios of disturbance. The result shows that the good improvement for the stabilization level of inertial stabilization platform has been achieved, and the reduction of LOS RMS errors is up to 40 per cent.