• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.270-275
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• 2009

In a high performance motor driving system, PI controller which is simple implementation is frequently used. But, PI controller has various problems because of an integrator saturation. Therefore, the various methods of an anti-windup have been studied to solve such problems. But, conventional anti-windup methods have still problem with large overshoot and long settling time in the driving conditions. In this paper, to improve such problem, it is proposed a new anti-windup strategy. Using LPF and PI controller, it is improved an overshoot and reduced settling time. Simulation results have verified usefulness of the proposed method using MATLAB/Simulink.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.9
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• pp.768-776
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• 2000

A robust high-speed motion controller is proposed. The proposed controller consists of the proximate time optimal servomechai는 (PTOD) for high-speed motion, disturbance observer (DOB) for robustness, friction compensator, and saturation handling element, In the proposed controller, DOB basically provides the chance to apply PTOS to non-double integrator systems by drastically reducing disturbances as well as unwanted signals due to difference between real system and the double integrator model. But, in DOB-based systems, if control input is saturated due to control input PTOS and/or DOB, overall system stability cannot be guaranteed. To solve this problem, ribust stability, when the control input is saturated. Eventually, a simple saturation handling element is inserted to maintain internal stability of overall system. Also, we explain the our two saturation handling methods, Additional Saturation Element (ASE_ and Self Adjusting Saturation (SAS), are the equivalent solutions of the saturation problem to maintain internal stability. The stability and performance of the proposed controller are verified through numerical simulations and experiments using a precision linear motor system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.975-980
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• 2004

Positioning system is widely used for many practical applications. This system requires a good controller to achieve high accuracy and fast response with simple and self-adjustable design. In order to satisfy the above requirements, a new practical controller for positioning systems, namely nominal characteristic trajectory following (NCTF) controller with PI compensator, has been proposed. However, the effect of actuator saturation can not be completely compensated for integrator windup when the object parameters vary. This paper presents a method to improve the NCTF controller by overcoming the problem of integrator windup by adopting a fuzzy system. The improvement of the NCTF controller is evaluated through simulation using a rotary positioning system. The simulation result has demonstrated the effectiveness of the compensated NCTF in overcoming the problem of integrator windup.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.10
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• pp.867-872
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• 2013

Many practical processes in industry have nonlinearities of some forms. One commonly encountered form is actuator saturation which can cause a detrimental effect known as integrator windup. Therefore, a strategy of attenuating the effects of integrator windup is required to guarantee the stability and performance of the overall control system. In this paper, optimal tuning of a PID (Proportional-Integral-Derivative) controller with an anti-windup scheme is presented to enhance the tracking performance of the PID control system in the presence of the actuator saturation. First, we investigate effective anti-windup schemes. Then, the parameters of both the PID controller and the anti-windup scheme are optimally tuned by an EA (Evolutionary Algorithm) such as the IAE (Integral of Absolute Error) is minimized. A set of simulation works on two high-order processes demonstrates the benefit of the proposed method.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.3
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• pp.231-239
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• 1999

An improved version of current-regulated delta modulator (CRDM) is investigated for the output cunent control of v voltage-source inverters that have transformer-coupled series resonant load and are operated at the resonant frequency. Conventional CRDM has not only CUlTent offset problem but also transformer flux saturation problem when i it is applied to induction heating systems that have transformel-coupled loads. To cope with these problems, the effect of flux saturation is analysed, and simple method to av이d the problem is proposed. And integral type of CRDM is a adopted to remove the cunent offset. The boundaries of integrator gain for stable operation is calculated using the c concept of sliding mode controL The validity of proposed strategy is vel퍼ed through simulations and prototype e experiments.

• Smart Structures and Systems
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• v.22 no.1
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• pp.95-103
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• 2018

Active vibration control via inertial mass actuators has been shown as an effective tool to significantly reduce human-induced vertical vibrations, allowing structures to satisfy vibration serviceability limits. However, a lot of practical obstacles have to be solved before experimental implementations. This has motivated simple control techniques, such as direct velocity feedback control (DVFC), which is implemented in practice by integrating the signal of an accelerometer with a band-pass filter working as a lossy integrator. This work provides practical guidelines for the tuning of DVFC considering the damping performance, inertial mass actuator limitations, such as stroke and force saturation, as well as the stability margins of the closed-loop system. Experimental results on a full scale steel-concrete composite structure (behaves similar to a footbridge) with adjustable span are reported to illustrate the main conclusions of this work.

• Journal of Mechanical Science and Technology
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• v.14 no.4
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• pp.369-379
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• 2000

In industrial production-distribution systems, production and purchasing rates, associated inventories, and sales are very critical for the profits of each component in the system. The objective of this study is to investigate an effective information control scheme for a production -distribution system by automatic feedback control techniques. In this work, a dynamic control scheme that has an integrated -error with state-feedback and filtering (ISFF) is proposed as a new algorithm for a dynamic controller. Generalized formulations of the dynamic control are proposed in the continuous-time and discrete-time cases. A methodology for an evaluation of ISFF controller gains using the eigen structure property is presented. When an upper-limit is imposed on the production capability by available factory space and capital equipment, supervisory control is provided to avoid integrator-windup and deterioration of system performance.

• Journal of Aerospace System Engineering
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• v.9 no.1
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• pp.12-18
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• 2015

The inter-conversion between different control laws in flight has a lot of risk. The SWM(Switching Mechanism) including logic and stand-by mode is designed to analyze the transient response of aircraft during inter-conversion between different control laws, based on the in-house software for non-real-time and real-time simulation. The SWM applies the fader logic of TFS(Transient Free Switch) to minimize the transient response of an aircraft during the inter-conversion, and applies the reset '0' type of the stand-by mode to prevent surface saturation due to integrator effect in the disengaged flight control law. The transition time is also important to minimize the objectionable transient response in the inter-conversion, as well as the transition control law design. This paper addresses the results of non-real-time simulation for the characteristics of transient response to different transition time to select the adequate transient time, and the real-time pilot evaluation, using SSWM(Software Switching Mechanism) and HSWM(Hardware Switching Mechanism), which is met for Level 1 flying qualities and assures safety of flight.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.5
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• pp.333-342
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• 2020

Power exchanges between the grid and the battery through a bidirectional DC-DC converter are essential for DC microgrid systems. In general, the battery is charged when the grid is connected, and the system is powered by the battery when the grid is disconnected. In this mode transition, the saturation of the voltage controller slows down output response and produces large transient errors in DC link voltage. To solve this problem, a novel anti-windup design is proposed to improve anti-windup performance further. The proposed method stabilizes DC bus voltage through a wider range of battery voltage with faster transition compared with that of conventional methods. The proposed method is verified through an experimental setup composed of a 125 W laboratory-scale DC microgrid system.