다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Disturbance-observer-based control (DOBC) and related methods have been researched and applied in various industrial sectors in the last four decades. This survey, at first time, gives a systematic and comprehensive tutorial and summary on the existing disturbance/uncertainty estimation and attenuation techniques, most notably, DOBC, active disturbance rejection control, disturbance accommodation control, and composite hierarchical antidisturbance control. In all of these methods, disturbance and uncertainty are, in general, lumped together, and an observation mechanism is employed to estimate the total disturbance. This paper first reviews a number of widely used linear and nonlinear disturbance/uncertainty estimation techniques and then discusses and compares various compensation techniques and the procedures of integrating disturbance/uncertainty compensation with a (predesigned) linear/nonlinear controller. It also provides concise tutorials of the main methods in this area with clear descriptions of their features. The application of this group of methods in various industrial sections is reviewed, with emphasis on the commercialization of some algorithms. The survey is ended with the discussion of future directions.

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Disturbance-Observer-Based Control and Related Methods—An Overview

This paper studies a number of quantized feedback design problems for linear systems. We consider the case where quantizers are static (memoryless). The common aim of these design problems is to stabilize the given system or to achieve certain performance with the coarsest quantization density. Our main discovery is that the classical sector bound approach is nonconservative for studying these design problems. Consequently, we are able to convert many quantized feedback design problems to well-known robust control problems with sector bound uncertainties. In particular, we derive the coarsest quantization densities for stabilization for multiple-input-multiple-output systems in both state feedback and output feedback cases; and we also derive conditions for quantized feedback control for quadratic cost and H/sub /spl infin// performances.

The sector bound approach to quantized feedback control | NOVA. The University of Newcastle's Digital Repository

This work presents a general framework for nonlinear systems subject to disturbances using disturbance observer based control (DOBC) techniques. A two-stage design procedure to improve disturbance attenuation ability of current linear/nonlinear controllers is proposed where the disturbance observer design is separated from the controller design. To facilitate this concept, a nonlinear disturbance observer is developed for disturbances generated by an exogenous system, and global exponential stability is established under certain condition. Furthermore, semiglobal stability condition of the composite controller consisting of a nonlinear controller and the nonlinear disturbance observer is established. The developed method is illustrated by the application to control of a two-link robotic manipulator.

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Disturbance observer based control for nonlinear systems

Stability and L2-gain analysis for switched delay systems: A delay-dependent method

In this paper, a new robust control is proposed for a class of dynamical systems with uncertainties. The considered dynamical systems may be nonminimum phase systems. The designed controller requires only input output measurement of the system. First, by using least square approximation technique, nonminimum phase systems are approximated by minimum phase systems. Then, the uncertainty is approximately estimated. Finally, based on the approximate minimum phase system and the estimate of the uncertainty, the robust control input is synthesized. Example and simulation results are presented to show the effectiveness of the proposed algorithm.

Robust Control for a Class of Dynamical Systems with Uncertainties

Piezoelectric actuators (PEAs) have been widely used in micro- and nanopositioning applications due to their fine resolution, rapid responses, and large actuating forces. However, a major deficiency of PEAs is that their accuracy is seriously limited by hysteresis. This paper presents adaptive model predictive control technique for reducing hysteresis in PEAs based on autoregressive exogenous model. Experimental results show the effectiveness of the proposed method.

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Tracking control of piezoelectric actuator using adaptive model

Control of nonlinear systems preceded by unknown hysteresis nonlinearities is a challenging task and has received great attention recently due to increasing industrial demands. In the literature, many mathematical models have been proposed to describe the hysteresis. The challenge addressed here is how to fuse those hysteresis models with available robust control techniques to have the basic requirement of stability of the system. The purpose of the paper is to show such a possibility by using the Prandtl-Ishlinskii (PI) hysteresis model. An adaptive variable structure control approach, serving as an illustration, is fused with the PI model without necessarily constructing a hysteresis inverse. The global stability of the system and tracking a desired trajectory to a certain precision are achieved. Simulations performed on a nonlinear system illustrate and further validate the effectiveness of the proposed approach.

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On the control of nonlinear systems with unknown Prandtl-Ishlinskii hysteresis

This paper discusses the model and control for ionic polymer-metal composite (IPMC) actuators. Firstly, a mathematical model of the IPMC actuator is constructed as a stable second order dynamical system preceded by a hysteresis representation. Then, an adaptive controller is synthesized for the IPMC actuator. The proposed control law ensures the global stability of the controlled IPMC system, and the position error of IPMC actuator can be controlled by choosing the design parameters. Experimental results confirm the effectiveness of the proposed method.

Control design for ionic polymer-metal composite based actuators

This paper gives a new formulation of the robust observers for the minimum phase dynamical systems with arbitrary relative degrees (with respect to the relation between disturbance-output) by applying the implicit observer techniques. For plants with relative degree one, the robust observer is constructed without any a priori on the disturbance. For plants with relative degree two, an identification of the integral of the disturbance is made by using the variable structure approach, the state vector is asymptotically expressed by the integrals of the input and output and the estimation of the integrals of the disturbance. For plants with relative degree higher than two, the observer formulation is stated as a conjecture. Numerical examples and simulation results are presented to show the effectiveness of the proposed algorithms.

Xinkai Chen

Papers

Robust Control for a Class of Dynamical Systems with Uncertainties

Tracking control of piezoelectric actuator using adaptive model

On the control of nonlinear systems with unknown Prandtl-Ishlinskii hysteresis

Control design for ionic polymer-metal composite based actuators

Design of the discontinuous observers