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

G A Ramos,John Cortés-Romero,Ramon Costa-Castelló

doi:10.1155/2015/380609

Abstract

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.

Highlights

Rejection of periodic disturbances has been a subject of great interest in control theory and engineering applications
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
repetitive control (RC) constitutes a very efficient methodology in control applications that require tracking and/or rejection of periodic signals. It is based on the internal model principle (IMP), requiring the inclusion of a periodic signal model in the control loop

Summary

Introduction

Rejection of periodic disturbances has been a subject of great interest in control theory and engineering applications. RC constitutes a very efficient methodology in control applications that require tracking and/or rejection of periodic signals (see [9]). It is based on the internal model principle (IMP), requiring the inclusion of a periodic signal model in the control loop. One of the main drawbacks of RC appears when the frequency of the signals is uncertain or varies with time. In these cases, the traditional RC suffers from a significant performance loss [10]. In order to solve this problem, different strategies have been reported in the literature: a variable structure RC has been proposed in [11], where the frequency of the internal model is adapted to follow the exogenous signal changes; a High Order

Methods

Results

Conclusion