Disturbance observer-based multirate control for rejecting periodic disturbances to the Nyquist frequency and beyond

Automatica ◽  
2017 ◽  
Vol 82 ◽  
pp. 49-58 ◽  
Author(s):  
Weili Yan ◽  
Chee Khiang Pang ◽  
Chunling Du
Keyword(s):  
Disturbance Observer ◽  
Nyquist Frequency ◽  
Periodic Disturbances ◽  
Multirate Control

Control law design for eliminating periodic disturbances above Nyquist frequency

2000 ◽  
Author(s):  
Richard Longman ◽  
Raphael Akogyeram ◽  
Jer-Nan Juang ◽  
Andrew Hutton
Keyword(s):  
Control Law ◽  
Nyquist Frequency ◽  
Periodic Disturbances

Robust Compensation of Periodic Disturbances by Multirate Control

2008 ◽  
Vol 44 (3) ◽  
pp. 413-418 ◽  
Author(s):  
Chang Duan ◽  
Guoxiao Gu ◽  
Chunling Du ◽  
Tow Chong Chong
Keyword(s):  
Periodic Disturbances ◽  
Multirate Control ◽  
Robust Compensation

Multirate iterative learning disturbance observer with measurement delay compensation for flexible spacecraft attitude stabilization subject to complex disturbances

2020 ◽  
pp. 107754632097736
Author(s):  
Tongfu He ◽  
Zhong Wu
Keyword(s):  
Control System ◽  
Attitude Control ◽  
Disturbance Observer ◽  
Iterative Learning ◽  
Flexible Spacecraft ◽  
Spacecraft Attitude ◽  
Delay Compensation ◽  
Attitude Control System ◽  
Periodic Disturbances ◽  
Measurement Delay

Complex disturbances with multifrequency components inevitably exist in the attitude control system of flexible spacecrafts. Multirate iterative learning disturbance observer (MILDO) is a promising solution to estimate and attenuate these disturbances much more accurately. However, measurement delay in the attitude measurement system may severely degrade the estimation performance of MILDO and even lead to instability of the control system. To suppress complex disturbances of flexible spacecrafts subject to a known measurement delay, a delay compensation-MILDO (DC-MILDO) is proposed in this study. First, an augmented model is constructed for the delayed disturbance by introducing slowly varying disturbance, multiple periodic disturbances, and the integral of the lumped disturbance as states. Then, a virtual measurement of the system is built by realigning the control torques with the delayed measurements in spacecraft attitude dynamics. According to the augmented model and the virtual measurement, a modified MILDO is designed by using multiple iterative learning structures. Based on the estimates of the modified MILDO, the lumped disturbance at current instant can be predicted by compensating time delay in the multifrequency components. Subsequently, a composite controller for flexible spacecraft is built by combining DC-MILDO with a robust controller based on Lyapunov–Krasovskii approach. Simulation results demonstrate the effectiveness of the proposed controller.

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