Attitude stabilization control of three-axis inertial stabilized platform using magnetically suspension system

An integrated 5-DoF (degree of freedom) active magnetic bearing (AMB) is designed for 3-DoF suspension and 2-DoF tilting of an azimuth frame in a three-axis inertially stabilized platform, and the current distribution control is designed to realize the 5-DoF suspension. The prototype of the azimuth frame with the integrated 5-DoF AMB is first introduced, and the force characteristics of axial and radial AMB units are respectively analyzed. Furthermore, based on the equivalent magnetic circuits of the axial AMB units in translation and tilting control loops, the current distribution principle is designed for axial AMB units to distribute the control currents reasonably. The simulations are conducted to demonstrate that the integrated 5-DoF AMB could stably suspend the azimuth frame, and the rotating accuracies of the azimuth frame around radial and axial axes are improved. In the experiment, the control currents in different control loops of the integrated 5-DoF AMB are effectively distributed to enhance efficiency and reduce power costs. The steady-state error of the azimuth frame is reduced from 0.018° to 0.0099° using magnetic forces of the integrated 5-DoF AMB system, and the maneuver time is shortened by 5 s. Therefore, the 5-DoF AMB using the current distribution method could improve the line-of-sight tracking precision of the azimuth frame.