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

This paper gives a new formulation of the robust observers for the single-input single-output dynamical systems with disturbances. Based on the design of the implicit observer techniques, a basic relation between an available signal and the disturbances is derived. Then the disturbance is identified by using the variable structure approach, and the observer is constructed through the VSS type disturbance estimator. Finally, the proposed VSS observer is applied to the disturbance observer of designing the controllers that cancel the disturbances.

Design of VSS observers and its application

Adaptive Control for Piezo-Actuated Nano-Positioner

In this paper, the design issue of adaptive fault-tolerant control (FTC) is investigated for a class of continuous-time 2-body point absorber wave energy converter (WEC) systems against actuator faults based on the iterative learning approach. The actuator faults considered in this paper contain both the lock-in-place and the loss of effectiveness faults, simultaneously. The WEC dynamic equations, including two moving parts (i.e., the float and the spar), are firstly transformed into a state-space model. Then, a group of novel iterative learning based adaptive multiple controllers are developed to decrease the tracking error between the measurement output and the desired output, and two novel adaptive laws are designed to cope with two types of actuator faults. Based on the theories mentioned above, a novel algorithm is provided to present the operation flows of both adaptive laws and iterative learning. Furthermore, a sufficient condition is obtained with the aid of proper Lyapunov function, such that the related closed-loop faulty-WEC system is asymptotically stable with a guaranteed $H_{\infty }$ performance index. Finally, an example with a set of physical parameters of a WEC dynamic model is worked out to verify the applicability and effectiveness of the proposed iterative learning based adaptive FTC strategy.

Adaptive Fault-Tolerant Control for a 2-Body Point Absorber Wave Energy Converter Against Actuator Faults: An Iterative Learning Control Approach

Based on the implicit observer techniques, a new expression of the state is obtained by the first order filters of the input, output and disturbance. For the minimum phase dynamical systems with arbitrary relative degrees (with respect to the relation between disturbance-output), the higher order filters of the disturbance is estimated by using the VSS equivalent control method. Then, by some new techniques, the lower order filter of the disturbance is estimated. Eventually, the disturbance is also estimated. Thus, the state vector is asymptotically expressed by the first order filters of the input and output and the estimate of the first order filters of the disturbance. The estimated state and the disturbance are applied to a controller to place a desired pole and to cancel the disturbance. Examples and simulation results are presented to show the effectiveness of the proposed algorithms.

State estimator and its application for systems with disturbances

The piezo-actuated nano-positioner is composed of a piezoelectric actuator (PEA) and a positioning mechanism (PM). Due to the existence of hysteretic nonlinearity in the PEA and the friction behavior in the PM, the accurate position control of the piezo-actuated stage is a challenging task. This paper discusses the adaptive control for the piezo-actuated nano-positioner, where the hysteresis is described by Prandtl-Ishlinskii model. The proposed control law ensures the zero output tracking of the controlled nano-positioner. Experimental results show the effectiveness of the proposed method.

Xinkai Chen

Papers

Design of VSS observers and its application

Adaptive Control for Piezo-Actuated Nano-Positioner

Adaptive Fault-Tolerant Control for a 2-Body Point Absorber Wave Energy Converter Against Actuator Faults: An Iterative Learning Control Approach

State estimator and its application for systems with disturbances

Adaptive high precision control for piezo-actuated nano-positioner