Accelerometer-Assisted Disturbance Feedforward Control of an Inertially Stabilized Platform
Qihui Bian, Yu Wang, Yong Ruan, Tao Tang
Abstract
Inertially stabilized platforms (ISPs) are extensively utilized to stabilize the line of sight (LOS) and achieve precise tracking regardless of various disturbances, whereas their disturbance suppression ability (DSA) is always limited by the system bandwidth. Therefore, a disturbance feedforward (DFF) method based on accelerometer measuring is proposed in this article, which breaks the feedback loop bandwidth limitation and, thus, improves the closed-loop performance of an ISP. To avoid signal coupling effects between traditional inertial loops, the feedback loop is designed, which encompasses the inner loop based on a high-bandwidth encoder as a non-inertial loop and the gyro-based outer loop as an inertial loop. The conventional model-based inverse control reduces the control bandwidth and high-frequency DSA due to the unrealizable differentiation in the system. Hence, the novel accelerometer-based feedforward controller is developed. We adopt the accelerometer integral to obtain high-bandwidth and high-precision disturbance signals and construct the low-pass filter instead of the conventional integrator. Finally, an accelerometer feedforward control scheme that combines acceleration integration with acceleration is conducted to further enhance the system DSA. Simulations and experiments demonstrate the validity of the presented approach.