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

Asymptotic Rejection of Periodic Disturbances With Fixed or Varying Period

2000 ◽  
Vol 123 (3) ◽  
pp. 324-329 ◽  
Author(s):  
Shiang-Hwua Yu ◽  
Jwu-Sheng Hu
Keyword(s):  
Design Method ◽  
Repetitive Control ◽  
Sampling Interval ◽  
Control Law ◽  
Integer Multiple ◽  
Tuning Method ◽  
Periodic Disturbances ◽  
Optimal Delay ◽  
Close Relationship ◽  
Tuning Methods

A constructive derivation of repetitive control is obtained, through attempting to derive a control law for asymptotic rejection of periodic disturbances. This derivation not only reveals a close relationship between iterative operator inversion and repetitive control, but also suggests a unified design method for a learning control algorithm. Also, based on the observation, digital repetitive control can be generalized to reject periodic disturbance whose period is not exactly an integer multiple of the sampling interval. This study introduces a delay filter in the digital repetitive control law, which optimally interpolates the signal between samples, thus effectively reconstructing the signal of the previous period and making the learning process of repetitive control successful. The proposed optimal delay filter can be updated easily according to different signal periods. Thus it is specifically suitable for on-line tuning when the signal period is changing. Compared with the available tuning methods, the proposed tuning method has excellent steady-state performance while maintaining fast transient and system robustness. The simulations on active noise cancellation within a duct confirm the superiority of this tuning method.

Adaptive Rejection of Unmatched General Periodic Disturbances by Dynamic Output Feedback

2013 ◽  
Vol 710 ◽  
pp. 491-495
Author(s):  
Peng Nian Chen
Keyword(s):  
Output Feedback ◽  
Closed Loop ◽  
Output Feedback Control ◽  
Control Law ◽  
Dynamic Output Feedback ◽  
Time Varying ◽  
Closed Loop System ◽  
Periodic Disturbances ◽  
Adaptive Output Feedback Control ◽  
Coefficient Vector

The paper considers rejection of unmatched general periodic disturbances with time-varying gains for a class of nonlinear systems. The period of the periodic disturbances is known, the gains of the disturbances depend on the output of the system, and the coefficient vector of the disturbance input channel is not assumed to be a Hurwitz vector. A novel filtered transformation is presented. Based on the filtered transformation, an adaptive output feedback control law is proposed, which guarantees that the output of the closed loop system converges to zero.

scholarly journals LPV Observer-Based Strategy for Rejection of Periodic Disturbances with Time-Varying Frequency

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
G. A. Ramos ◽  
Ramon Costa-Castelló ◽  
John Cortés-Romero
Keyword(s):  
Control Law ◽  
Periodic Signal ◽  
Test Bed ◽  
Linear Parameter Varying ◽  
Disturbance Estimation ◽  
Periodic Disturbances ◽  
Time Varying Frequency ◽  
Harmonic Decomposition ◽  
Disturbance Term ◽  
Resonant Control

Rejection of periodic disturbances is an important issue in control theory and engineering applications. Conventional strategies like repetitive control and resonant control can deal adequately with this problem but they fail when the frequency of the disturbance varies with time. This paper proposes a Linear Parameter Varying (LPV) resonant observer-based control for periodic signal rejection which is able to deal with the changes in frequency of the disturbance signal. The observer includes, in an embedded way, an internal model of the disturbance that is based on its harmonic decomposition. In this way, the frequency of the disturbance signal constitutes a parameter that can be adjusted according to the variations of the signal. The resulting disturbance estimation is then used by a control law that cancels the periodic disturbance term while controlling a specified tracking task. The proposed scheme lets the control designer address the disturbance estimation and tracking problems separately. Experimental results, on a mechatronic test bed, show that the proposed LPV resonant observer-based control successfully rejects periodic disturbances under varying frequency conditions.

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