A novel algorithm for unknown periodic disturbance cancellation in HDDs

Author(s):  
Hui Li ◽  
Chunling Du ◽  
Youyi Wang
Author(s):  
Jeng-Wen Lin ◽  
Chih-Wei Huang ◽  
Hao-Ping Wen

This paper presents repetitive control laws in real time using matched basis functions. These laws adjust the command given a feedback control system in order to eliminate tracking errors, resulting from in general a periodic disturbance and a non-periodic disturbance. The periodic error can be reduced by linear basis functions while the non-periodic error by the projection algorithm along with the wavelet filtering. The control laws do not use a system model, but instead the control action is chosen to be a linear combination of chosen input basis functions, and the corresponding output basis functions are obtained, nominally by experiment. The repetitive control laws use the projection algorithm to compute the output components on the output basis functions, and then the corresponding input components are adjusted accordingly. The output signals are reconstructed via the wavelet filtering before they are feedback to the controller. Numerical experiments show that the repetitive controllers are quite effective. In particular, the output tracking errors are further reduced because of the introduction of the wavelet filtering when compared to the previous work. In general, the repetitive control laws developed here can be used for the purpose of precision machinery control.


2010 ◽  
Vol 38 (1) ◽  
Author(s):  
R.J. Schilling ◽  
A.F. Al-Ajlouni ◽  
E.S. Sazonov ◽  
A.K. Ziarani

Automatica ◽  
2004 ◽  
Vol 40 (4) ◽  
pp. 631-637 ◽  
Author(s):  
L.J. Brown ◽  
Qing Zhang

1996 ◽  
Vol 118 (3) ◽  
pp. 416-424 ◽  
Author(s):  
Alexei Sacks ◽  
Marc Bodson ◽  
Pradeep Khosla

This paper considers the implementation of an adaptive algorithm for periodic disturbance cancellation. It is shown that the maximum rate of adaptation can be calculated precisely based on measurements of the system’s frequency response. The response of the closed-loop system to additional disturbances can also be computed on that basis. The results are verified experimentally on a high track density magnetic disk drive. Excellent matching between the theoretical and experimental results is observed. An improved method is also proposed that leads to faster convergence of the adaptive algorithm and better disturbance rejection capabilities. The results of this paper significantly enhance the ability of the control engineer to design and analyze adaptive feedforward algorithms for a variety of applications where periodic disturbances are encountered.


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