scholarly journals Optimal Disturbance Observer Design for High Tracking Performance in Motion Control Systems

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1633
Author(s):  
Wonhee Kim ◽  
Sangmin Suh
Keyword(s):  
Disturbance Observer ◽  
Closed Loop ◽  
Inverse Dynamics ◽  
Hard Disk Drives ◽  
Observer Design ◽  
Disk Drives ◽  
Closed Loop Systems ◽  
Baseline Weight ◽  
The Stability ◽  
Target Plant

In this paper, a stability-driven optimal disturbance observer (DO) is proposed. The proposed method does not require any plant inverse dynamics to detect introduced disturbances or a stabilizing Q filter. It does not require additional compensators to resolve causality problems, due to the relative degree, or filters to solve instability problems of non-minimum phase plants. Using this method enables wideband and narrowband disturbances to be attenuated by simply multiplying the corresponding peak filters by the baseline weight function. Furthermore, the proposed DO guarantees the stability of closed-loop systems because the already designed outer-loop systems are considered as a target plant to be stabilized and because of the Lyapunov stability-based H∞ control. In the application example, it was confirmed that the proposed method is effective, and the position error signals were improved by 20.9% in commercial hard disk drives and 36.6% in optical image stabilization systems.

scholarly journals Estimation Error Based Disturbance Observer Design for Flexible Loop Shaping

Electronics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 358 ◽  
Author(s):  
Sangmin Suh
Keyword(s):  
Disturbance Observer ◽  
Closed Loop ◽  
Control Structure ◽  
Storage Systems ◽  
Estimation Error ◽  
Observer Design ◽  
Experimental Results ◽  
External Disturbances ◽  
Flexible Loop ◽  
Closed Loop Systems

This note presents an estimation error based disturbance observer (EEDOB) to reduce the effects of external disturbances. In the proposed control structure, a difference between an estimator output and a plant output is considered as an equivalent disturbance. Therefore, when a disturbance appears, the proposed disturbance observer (DOB) is activated. Unlike conventional DOB, this method does not require the plant inverse model or additional stabilizing filters. In addition, the proposed method always satisfies closed loop systems stability, which is definitely different from conventional DOB. To verify the effectiveness, this method was applied to commercial storage systems. From the experimental results, it is confirmed that tracking performance is improved by 23.5%.

Reference Signal Shaping for Closed-Loop Systems With Application to Seeking in Hard Disk Drives

2012 ◽  
Vol 20 (2) ◽  
pp. 335-345 ◽  
Author(s):  
Uwe Boettcher ◽  
Dirk Fetzer ◽  
Hui Li ◽  
Raymond A. de Callafon ◽  
Frank E. Talke
Keyword(s):  
Closed Loop ◽  
Reference Signal ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Closed Loop Systems

Direct Adaptive Disturbance Observer Design for Rejecting the Narrow-Band Disturbance With Unknown Frequency in Hard Disk Drives

2009 ◽  
Author(s):  
Qixing Zheng ◽  
Masayoshi Tomizuka
Keyword(s):  
Disturbance Observer ◽  
Narrow Band ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Observer Design ◽  
Disk Drives ◽  
Optimal Value ◽  
Band Pass ◽  
Servo Controller

This paper presents an adaptive add-on compensator to handle a single narrow-band disturbance with unknown frequency in hard disk drives (HDDs). A disturbance observer (DOB) loop with a narrow band pass Q filter is built around the baseline servo controller to reject the narrow-band disturbance. The frequency parameter of the Q filter is directly adapted to the optimal value in the sense of minimizing the track following track mis-registration (TMR). The performance of the proposed compensator is demonstrated by simulation on an open-source realistic hard disk drive system.

H∞ disturbance observer design for high precision track following in hard disk drives

2009 ◽  
Vol 3 (12) ◽  
pp. 1591-1598 ◽  
Author(s):  
C.K. Thum ◽  
C. Du ◽  
E.H. Ong ◽  
B.M. Chen ◽  
F.L. Lewis
Keyword(s):  
High Precision ◽  
Disturbance Observer ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Observer Design ◽  
Disk Drives

scholarly journals Suboptimal Disturbance Observer Design Using All Stabilizing Q Filter for Precise Tracking Control

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1434 ◽  
Author(s):  
Wonhee Kim ◽  
Sangmin Suh
Keyword(s):  
Design Method ◽  
Industrial Applications ◽  
Point Of View ◽  
Observer Design ◽  
Linear Matrix ◽  
External Disturbances ◽  
Closed Loop Systems ◽  
Control Target ◽  
The Stability ◽  
Unified Index

For several decades, disturbance observers (DOs) have been widely utilized to enhance tracking performance by reducing external disturbances in different industrial applications. However, although a DO is a verified control structure, a conventional DO does not guarantee stability. This paper proposes a stability-guaranteed design method, while maintaining the DO structure. The proposed design method uses a linear matrix inequality (LMI)-based H∞ control because the LMI-based control guarantees the stability of closed loop systems. However, applying the DO design to the LMI framework is not trivial because there are two control targets, whereas the standard LMI stabilizes a single control target. In this study, the problem is first resolved by building a single fictitious model because the two models are serial and can be considered as a single model from the Q-filter point of view. Using the proposed design framework, all-stabilizing Q filters are calculated. In addition, for the stability and robustness of the DO, two metrics are proposed to quantify the stability and robustness and combined into a single unified index to satisfy both metrics. Based on an application example, it is verified that the proposed method is effective, with a performance improvement of 10.8%.

Application of Mixed H2/H∞ Data Driven Control Design to Dual Stage Hard Disk Drives

2018 ◽  
Author(s):  
Omid Bagherieh ◽  
Prateek Shah ◽  
Roberto Horowitz
Keyword(s):  
Closed Loop ◽  
Transfer Functions ◽  
Hard Disk Drives ◽  
Control Design ◽  
Hard Disk ◽  
Data Driven ◽  
Disk Drives ◽  
Design Strategies ◽  
Data Driven Approach ◽  
Dual Stage

A data driven control design approach in the frequency domain is used to design track following feedback controllers for dual-stage hard disk drives using multiple data measurements. The advantage of the data driven approach over model based approach is that, in the former approach the controllers are directly designed from frequency responses of the plant, hence avoiding any model mismatch. The feedback controller is considered to have a Sensitivity Decoupling Structure. The data driven approach utilizes H∞ and H2 norms as the control objectives. The H∞ norm is used to shape the closed loop transfer functions and ensure closed loop stability. The H2 norm is used to constrain and/or minimize the variance of the relevant signals in time domain. The control objectives are posed as a locally convex optimization problem. Two design strategies for the dual-stage hard disk drive are presented.

Optimal Decoupled Disturbance Observers for Dual-Input Single-Output Systems

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Xu Chen ◽  
Masayoshi Tomizuka
Keyword(s):  
Disturbance Observer ◽  
Filter Design ◽  
Spectral Characteristics ◽  
Hard Disk Drives ◽  
Disk Drives ◽  
Single Input Single Output ◽  
Control Approach ◽  
Single Output ◽  
Dual Stage ◽  
Single Input

The disturbance observer (DOB) has been a popular robust control approach for servo enhancement in single-input single-output systems. This paper presents a new extension of the DOB idea to dual- and multi-input single-output systems, and discusses an optimal filter design technique for the related loop-shaping. The proposed decoupled disturbance observer (DDOB) provides the flexibility to use the most suitable actuators for compensating disturbances with different spectral characteristics. Such a generalization is helpful, e.g., for modern dual-stage hard disk drives, where enhanced servo design is becoming more and more essential in the presence of vibration disturbances.

Reduction Methods of Structure Models for Control System Purposes

2016 ◽  
Vol 248 ◽  
pp. 119-126 ◽  
Author(s):  
Andrzej Koszewnik ◽  
Zdzisław Gosiewski
Keyword(s):  
Control System ◽  
High Frequency ◽  
Closed Loop ◽  
Flexible Structures ◽  
Low Frequency ◽  
Point Of View ◽  
Closed Loop Systems ◽  
System A ◽  
Reduction Methods ◽  
The Stability

To design vibration control system for flexible structures their mathematical model should be reduced. In the paper we consider the influence of the model reduction on the dynamics of the real closed-loop system. A simply cantilever beam is an object of consideration since we are able to formulate the exact analytical model of such structure. As a result of reduction the model with low frequency resonances is usually separated from the high frequency dynamics because high frequency part of the model is naturally strong damped. In order to estimate dynamical system for control purposes in the paper we applied a few orthogonal methods such as: modal, Rayleigh-Ritz and Schur decompositions. As it is shown all methods well calculate resonances frequencies but generate different anti-resonances frequencies. From control strategy in point of view of the flexible structures these anti-resonances have significantly influence on the stability and dynamics of the closed-loop systems.

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