Abstract
The micro-electro-mechanical system (MEMS) accelerometer is widely adopted in many engineering control systems due to its extraordinary performance with high bandwidth, small size and low weight. However, massive drift caused by its insensitively at low frequency is the main factor which limits its performance. It leads to integral saturation when the feedforward method is used and hinders the improvement of disturbance suppression ability at low frequency, which is a significant factor for evaluating the closed-loop performance of a high-precision tracking system. To solve this problem, a modified disturbance observer structure and its corresponding new controller, which can improve disturbance suppression performance at low frequency by effectively rejecting more drift and weakening the occurrence possibility of integral saturation when drift exists, are proposed. Detailed analyses and a series of comparative experimental results verify that the proposed method can effectively enhance disturbance suppression performance at low frequency.
Highlights
The tracking control system (TCS) is widely used in long-distance communication, astronomical observation, target tracking and other scientific fields [1,2,3,4,5]
In the TCS, gyroscopes and position detectors are generally used as sensors to implement a dual-loop feedback control (DFC) to stabilize the controlled platforms [7,8] Gyroscopes with a small delay are used to build a high-bandwidth inner loop and the tracking performance of the TCS mainly depends on the position information from position detectors such as a charge-coupled device (CCD)
In order to improve the performance of control bandwidth and disturbance suppression, the micro-electro-mechanical system (MEMS) accelerometer has been widely recommended for the TCS due to its high bandwidth, small size and low weight [11,12,13,14,15]
Summary
The tracking control system (TCS) is widely used in long-distance communication, astronomical observation, target tracking and other scientific fields [1,2,3,4,5]. To improve the performance of the TCS, the feedforward method based on direct measurement is introduced as it can suppress most of the theoretical external disturbances [19,20] It involves additional cost for another sensor and specific environments with low measurable noise. Deng recommended the disturbance observer for an acceleration feedback control loop with a MEMS accelerometer, which improved disturbance suppression ability only at intermediate frequency [30]. To solve the above-mentioned problem, in this paper we propose the modified disturbance observer (MDOB) method to enhance disturbance suppression performance at low frequency in the TCS, which weakens the occurrence possibility of integral saturation when drift exists.
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