High-bandwidth angular jitter measurement for acquisition, tracking and pointing system

Abstract

In order to achieve precise pointing and high-resolution imaging, acquisition, tracking and pointing (ATP) system is usually required to stabilize the line-of-sight (LOS) within arc-second or even higher level. In case of ATP system mounted on moving platform, broadband angular disturbance is the most serious factor to prevent the LOS being stabilized. Due to the limited sampling frequency of detectors, the angular disturbance is usually mitigated by incorporating inertial stabilized platform (ISP) and fast steering mirror (FSM) into ATP system. The need for small, inexpensive inertial angular rate sensors(ARSs), which may be employed in these devices to measure angular jitter at sufficiently wide bandwidth, is urgent. However, there is no single angular rate sensor (ARS) currently available that could measure angular jitter from DC to hundreds of hertz while maintaining comparable accuracy. Multi-sensor fusion is a practical solution to broadband angular jitter measurement for the purpose of jitter control. In this paper, the measurements from Magnetohydrodynamics (MHD) ARS and MEMS gyro are blended together using closed-loop fusion (CLF) method. The approach does not rely on accurate models or transfer functions of sensors, and meanwhile, can be easily implemented in real-time system. Experimental results indicate that the measuring bandwidth of CLF method is within overall frequency range covered by MHD ARS and MEMS gyro.