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%.

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 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%.

Nonlinear adaptive position tracking of an electro-hydraulic actuator

2015 ◽  
Vol 229 (17) ◽  
pp. 3252-3265 ◽  
Author(s):  
Kai Guo ◽  
Jianhua Wei ◽  
Qiyan Tian
Keyword(s):  
Disturbance Observer ◽  
Lyapunov Theory ◽  
Observer Design ◽  
Estimation Accuracy ◽  
Load Force ◽  
Position Tracking ◽  
Hydraulic Actuator ◽  
Parameter Uncertainties ◽  
External Disturbances ◽  
Tracking Controller

This paper deals with position tracking control of a single-rod electro-hydraulic actuator subject to external disturbances and parameter uncertainties. In previous disturbance observer design methodologies for electro-hydraulic actuators, parameter uncertainties have been commonly regarded as disturbances and lumped together with external perturbations. However, in practical electro-hydraulic systems, system parameters are unknown and varying. If considerable parameter uncertainties exist in the system or if the disturbance dynamics induced by parameter uncertainties exceed the bandwidth of the disturbance observer, estimation accuracy will degrade, which will significantly affect system performance. To solve this problem, an extended disturbance observer is proposed in this paper to estimate disturbances while dealing with parameter uncertainties. In addition, a nonlinear position tracking controller is designed for position tracking based on the proposed disturbance observer using a backstepping technique. The proof of the stability of the overall closed-loop system is based on Lyapunov theory. The performance of the proposed controller is verified through simulations and experiments using a shock absorber as a load force generator. A detailed nonlinear physical model of the load force is developed and implemented in the simulation. The results show that the proposed nonlinear position tracking controller, together with the extended disturbance observer, provide excellent tracking performance in the presence of parameter uncertainties and external disturbances.

Passivity-Based Disturbance Observer Design

2020 ◽  
Author(s):  
Ying-Chun Chen ◽  
Craig Woolsey
Keyword(s):  
Disturbance Observer ◽  
Design Method ◽  
Estimation Error ◽  
Parameter Tuning ◽  
Observer Design ◽  
Nonlinear Observer ◽  
Design Parameters ◽  
Nonlinear Feedback ◽  
Initial Application ◽  
Wide Range

Abstract A design method is proposed for a nonlinear disturbance observer based on the notion of passivity. As an initial application, we consider here systems whose structure comprises a set of integrator cascades, though the proposed approach can be extended to a larger class of systems. We describe an explicit procedure to choose the output of the system and to design the nonlinear feedback law used by the observer, provided the system satisfies a sufficient condition for output feedback semi-passification. The output injection term in the observer scales the measurement residual with a nonlinear gain that depends on the output and a set of static design parameters. We provide guidance for parameter tuning such that the disturbance tracking performance and the transient response of the estimation error can be intuitively adjusted. Example applications to two nonlinear mechanical systems illustrate that the proposed nonlinear observer design method is quite effective, producing an observer that can estimate a wide range of disturbances without any need to know or assume the disturbance dynamics.

Disturbance observer design and vibration control for a flexible aircraft wing

2017 ◽  
Vol 40 (13) ◽  
pp. 3760-3773 ◽  
Author(s):  
Yuanyuan Zhang ◽  
Jinkun Liu ◽  
Wei He
Keyword(s):  
Differential Equations ◽  
Vibration Control ◽  
Disturbance Observer ◽  
Observer Design ◽  
Distributed Parameter ◽  
Closed Loop System ◽  
Aircraft Wing ◽  
External Disturbances ◽  
Flexible Aircraft ◽  
Infinite Dimensional

This study focuses on the disturbance observer design and vibration control problems for a flexible aircraft wing system. The flexible aircraft wing is modeled as a coupled twist-bending infinite dimensional distributed parameter system. The dynamic equations and boundary conditions are described by partial differential equations and ordinary differential equations, respectively. In this paper, an infinite dimensional disturbance observer is proposed to estimate both the boundary disturbances and the distributed spatiotemporally varying disturbances. Considering the coupling between the bending deformation and the twist deformation, a boundary controller is proposed to suppress the vibration and inhibit the adverse effects of external disturbances. By using the proposed disturbance observer and controller, the uniform boundednesss of the closed-loop system is validated through theoretical analysis. Finally, simulation results are carried out to illustrate the effectiveness of the proposed infinite dimensional disturbance observer and boundary controller.

Direct Adaptive CMAC PI Control for Uncertain Nonlinear Systems with Measurable Output Feedback

2013 ◽  
Vol 479-480 ◽  
pp. 612-616
Author(s):  
Chun Sheng Chen
Keyword(s):  
Nonlinear Systems ◽  
Closed Loop ◽  
Control Structure ◽  
Loop System ◽  
Pi Control ◽  
Uncertain Nonlinear Systems ◽  
Closed Loop System ◽  
External Disturbances ◽  
Lyapunov Stability Criterion ◽  
System Output

A stable direct adaptive CMAC PI controller for a class of uncertain nonlinear systems is investigated under the constrain that only the system output is available for measurement. First, a state observer is used to estimate unmeasured states of the systems. Then, the PI control structure is used for improving robustness in the closed-loop system and avoiding affection of uncertainties and external disturbances. The global asymptotic stability of the closed-loop system is guaranteed according to the Lyapunov stability criterion. To demonstrate the effectiveness of the proposed method, simulation results indicate that the proposed approach is capable of achieving a good trajectory following performance without the knowledge of plant parameters.

Resilient anti-disturbance H∞ control for turbofan systems

2020 ◽  
Vol 42 (14) ◽  
pp. 2686-2697
Author(s):  
Yankai Li ◽  
Mou Chen ◽  
Tao Li ◽  
Huijiao Wang ◽  
Yu Kang
Keyword(s):  
Disturbance Observer ◽  
Closed Loop ◽  
Control Method ◽  
Sufficient Conditions ◽  
Lyapunov Stability Theory ◽  
Control Technique ◽  
Linear Matrix ◽  
Asymptotically Stable ◽  
Matrix Inequality ◽  
Closed Loop Systems

The problem of [Formula: see text] control is investigated for turbofan systems with uncertain parameters and multiple disturbances in this paper. Some disturbances with partly known information are described via an external system, and other disturbances are assumed to be [Formula: see text] norm bounded. According to the disturbance-observer-based-control (DOBC) method and resilient [Formula: see text] control technique, a robust resilient controller is designed to reject and attenuate the influence of these disturbances, and guarantees that closed-loop systems are asymptotically stable with [Formula: see text] performance. Some solvable sufficient conditions are obtained based on the linear matrix inequality (LMI) technique and Lyapunov stability theory. Finally, a simulation is presented to show the robustness and effectiveness of the developed resilient anti-disturbance [Formula: see text] control method.

Disturbance Observer in Robust DC Motor Control

2014 ◽  
Vol 614 ◽  
pp. 219-223
Author(s):  
Hong Cheng Huang ◽  
Yi Zhang ◽  
Heng Deng
Keyword(s):  
Motion Control ◽  
Disturbance Rejection ◽  
Disturbance Observer ◽  
Control Structure ◽  
Specific Method ◽  
Motion Controller ◽  
External Disturbances ◽  
Dc Motor Control ◽  
Proportional Derivative Controller ◽  
Two Degree Of Freedom

The disturbance observer is a specific method of designing a two degree of freedom control structure to achieve insensitivity to modeling error and disturbance rejection. It has been successfully applied in a variety of motion control applications. In motion control, the major sources of uncertainties are friction, inertia, and external disturbances. These uncertainties should be taken into account by any robust motion controller. In this paper, this element is a PD (proportional-derivative) controller. The disturbance observer proves its advantages through the simulation and experiments. With disturbance observer, better tracking performance can be achieved with less control energy.

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