Inertially Stabilized Platform for Airborne Remote Sensing Using Magnetic Bearings

Abstract

Multiaxis gimbal configurations are commonly used in the line of sight stabilization systems for airborne remote sensing. Although these configurations are cost-effective, system performances deteriorate in the case of large payload, due to nonlinear friction and bandwidth limit of the servo loops. In this paper, a novel maglev dual-stage inertially stabilized platform is described, which encompasses a two-axis gimbal assembly as the coarse stage and a 5-DOF (degree of freedom) magnetic bearing as the fine stage. The coarse stage is mounted on the aircraft consisting of a lateral gimbal and an elevation gimbal to isolate the large angular motion of the vehicle and provide coarse pointing. The payload instrument is suspended in the elevation gimbal utilizing an electromagnetic bearing with vernier gimbaling capability to compensate the residual angular motion of the gimbal. An actual prototype of the proposed platform was designed and fabricated to illustrate the framework. The performance of the magnetic suspension system is investigated through experiments. Detailed models are established for the magnetic suspension system and the gimbal stabilizing system to develop the control strategy of the dual-stage system. Finally, the effectiveness of the design is demonstrated through simulation studies, where a 3.5 times stabilization precision improvement is prefigured compared to a reference conventional gimbal system.