• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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• pp.255-259
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• 1996

This paper presents active vibration control of a rotating cantilevered beam using piezoceramic actuators. A governing equation of motion is obtained by the Hamilton's principle and expressed in the state space representation. Subsequently, an H$_{\infty}$ control which is robust to system uncertainties is synthesized through the loop shaping design procedure. Computer simulations for the steady-state vibration control are undertaken in order to demonstrate the effectiveness and robustness of the proposed control methodology..y.

• 한국정밀공학회지
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• 제25권10호
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• pp.67-76
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• 2008

In this research, a simple technique for designing PID controller, which guarantees robust stability for two-mass systems with parameter uncertainties as well as rigid-body behavior and zero steady-state error,is described. As well, such a PID controller is designed to mate two important frequencies, at which the given system is excited, very close so that an appropriate reference profile generated by using command shaping techniques can cover those two frequencies. Root-locus analysis. which shows traces of closed-loop poles for the given system, is used to design this PID controller. Finally, feedforward controller is added to improve tracking performance of the closed-loop system. Simulation for a system with a flexible mode and parameter uncertainties is executed to prove the feasibility of this technique.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1244-1254
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• 2015

This paper proposes a new method for tuning a linear quadratic - proportional integral derivative controller for second order systems to simultaneously meet the time and frequency domain design specifications. The suitable loop-shape of the controlled system and the desired step response are considered as specifications in the time and frequency domains, respectively. The weighting factors, Q and R of the LQ controller are determined by the algebraic Riccati equation with respect to the limiting behavior and target function matching. Numerical examples show the effectiveness of the proposed LQ-PID tuning method

• 한국통신학회논문지
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• 제25권3B호
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• pp.570-576
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• 2000

본 논문은 LQ-서보구조를 부분적 상태 피드백을 갖고 있는 PI제어기로 해석하여 LQ-서보형 PI 제어기를 제안하고 이를 설계하기 위하여서 종전의 LQ-servo 설계 기법의 설계 매개 변수에 가중치를 도입하여 설계 앨고리즘을 보다 유연성 있게 개발하는데 있다. 제안된 앨고리즘은 설계 루프 전달 함수의 최대 및 최소 특이값을 저주파와 고주파에서의 일치를 향상시킬수 있을 뿐만 아니라 성능 향상을 위해 루프 형상을 유연성 있게 설계할 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제35권6호
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• pp.820-828
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• 2011

에너지 절약은 해상운송분야에서 이익을 내기 위한 가장 중요한 요인 중 하나이다. 연료 소비율을 낮추기 위해서는 가능한 한 선박의 추진효율을 높여야만 한다. 추진효율은 추진기관과 낮은 회전속도에서 더 좋은 효율을 갖는 프로펠러의 조합에 의존한다. 기관은 저속이 될수록 연료분사과정에서의 지연시간으로 인해 회전 토크 변동이 심해진다. 본 연구에서는 강인 제어이론을 적용하여 강인 안정성과 강인 성능을 고려한 기관 속도제어기들, 즉 준최적 $H_{\infty}$제어기, $H_{\infty}$루프-성형 제어기 및 ${\mu}$-제어기를 설계한다. 컴퓨터 시뮬레이션 결과로부터 이들 3가지 제어기의 타당성을 검토한다.

• 한국전자통신학회논문지
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• 제11권12호
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• pp.1209-1218
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• 2016

4대의 전동실린더를 이용하여 대형 유리판과 같은 부하를 신속하고 안전하게 이송하기 위해서는 동기오차가 허용된 범위 내에서 지속적으로 유지되어야 한다. 본 연구에서는 4대 이상의 전동실린더 간의 동기화에 적용 가능한 동기제어기법이 제안된다. 이 동기제어시스템은 디커플링 구조에 기반을 두고 있으며, 기준모델, 위치제어기 그리고 동기제어기로 구성된다. 기준모델은 각각의 실린더에 대해 상호 분리된 동기오차와 제어입력의 계산이 가능하도록 한다. I-PD형의 위치제어기는 각 실린더가 오버슈트와 입력포화를 일으키지 않고 지령을 추종하도록, 그리고 진상보상기형의 동기제어기는 루프정형을 통해 안정적으로 정밀한 동기가 되도록 설계 된다. 끝으로 토크외란이 인가된 상태에서도 4개의 실린더가 신속하고 안정적으로 동기를 유지하면서 목표지점에 도달됨을 시뮬레이션으로 검증한다.

• International Journal of Control, Automation, and Systems
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• 제5권5호
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• pp.547-558
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• 2007

This paper proposes a simpler solution to the stabilization problem of a special class of nonlinear underactuated mechanical systems which includes widely studied benchmark systems like Inertia Wheel Pendulum, TORA and Acrobot. Complex internal dynamics and lack of exact feedback linearizibility of these systems makes design of control law a challenging task. Stabilization of these systems has been achieved using Energy Shaping and damping injection and Backstepping technique. Former results in hybrid or switching architectures that make stability analysis complicated whereas use of backstepping some times requires closed form explicit solutions of highly nonlinear equations resulting from partial feedback linearization. It also exhibits the phenomenon of explosions of terms resulting in a highly complicated control law. Exploiting recently introduced Dynamic Surface Control technique and using control Lyapunov function method, a novel nonlinear controller design is presented as a solution to these problems. The stability of the closed loop system is analyzed by exploiting its two-time scale nature and applying concepts from Singular Perturbation Theory. The design procedure is shown to be simpler and more intuitive than existing designs. Design has been applied to important benchmark systems belonging to the class demonstrating controller design simplicity. Advantages over conventional Energy Shaping and Backstepping controllers are analyzed theoretically and performance is verified using numerical simulations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.46-51
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• 2001

To reach high areal density, less track pitch is expected and more servo bandwidth is required. One approach to overcoming the problem is by using dual stage servo system. In this system, a voice coil motor (VCM) is used as the primary stage while a milliactuator is used as the secondary stage. We have suggested new milliactuator based on the shear mode of piezoelectric elements to drive the head suspension assembly. In this paper, we introduce controller design method, PQ method. PQ method reduces the controller design problem for DISO(dual-input/single-output) systems to two standard controller design problems for SISO(single-input/single-output) problems. The first part of PQ method directly address the issue of actuator output contribution, and the second part allows the use of traditional loop shaping to achieve the overall system performance. This paper shows how to employ the PQ method to meet aggressive close-loop performance specifications for a disk drive system with a VCM and piezoelectric milliactuator.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.88-97
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• 2013

This paper presents a robust air-to-fuel ratio (AFR) control algorithm for managing exhaust gas recirculation (EGR) systems. In order to handle production tolerance, deterioration and parameter-varying characteristics of the EGR system, quantitative feedback theory (QFT) is applied for designing the robust AFR control algorithm. A plant model of EGR system is approximated by the first order transfer function plus time-delay (FOPTD) model. EGR valve position and AFR of exhaust gas are used as input/output variables of the plant model. Through engine experiments, parameter uncertainty of the plant model is identified in a fixed engine operating point. Requirement specifications of robust stability and reference tracking performance are defined and these are fulfilled by the following steps: during loop shaping process, a PID controller is designed by using a nominal loop transmission function represented on Nichols chart. Then, the frequency response of closed-loop transfer function is used for designing a prefilter. It is validated that the proposed QFT-based AFR control algorithm successfully satisfy the requirements through experiments of various engine operating points.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.434-437
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• 1997

In this paper, we present an $H^{\infty}$ controller design of RTP system satisfying robust stability and performance using weighted mixed sensitivity minimization. In industrial fields, RTP system is widely used for improving the oxidation and the annealing in semiconductor manufacturing process. The main control factors are temperature control of wafer and uniformity in the wafer. The control of temperature and uniformity has been solved by PI control method. We improve robust stability and performance of RTP system by the design of $H^{\infty}$ controller using the weighted mixed sensivity function. An example is proposed to show the validity of proposed method.d.