• Journal of Energy Engineering
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• v.5 no.1
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• pp.28-33
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• 1996

This study was carried out find out the appropriate tuning method of PID controller for a package type gas engine cogeneration system in terms of stabilizing the engine coolant temperature and system heat balance. In order to acquire the proper parameters of the controller, a system transfer function was set as a first order plus dead time model and thereafter model parameters were determined by using several tuning methods. And, with determined values of parameters and the system transfer functions, optimal turning method was selected by simulating the process using MATLAB. From the experimental results, it was found that obtained PID gains made the system stable in various operating conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.2
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• pp.219-225
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• 2002

Parameter tuning methods by Ziegler-Nichols for PID controllers are generally classified into Z-N(1) and Z-N(2). The purpose of this paper is to describe what relations exist between the methods of Z-N(1) and Z-N(2), or how Z-N(1) can be originated from Z-N(2) by analyzing one loop control system composing of P or PI controller and time delay process. In this paper, for the first step to seek mutual relations, the simple formulas of Z-N(2) are transformed into those composing of the same parameters as Z-N(1) which is derived from the analysis of frequency characteristics. Then, the approximation of the actual ultimate frequency is proposed as important premise in the translation between Z-N(1) and (2). Such equalization and approximation brings a simple approximated formula which can explain how Z-N(1) is originated from the Z-N(2) in the form of formula.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.5-10
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• 2005

We deal with the sliding mode control using the time delay estimation. The time delay estimation is able to weaken the need for obtaining a quantitative plant model analogous to the real plant so the sliding mode control with a time delay estimation (SMCTE) is very suitable for plant such as SMA actuators whose quantitative model is difficult to obtain. We have already studied the application of the time delay control (TDC) to SMA actuators in other literature. Based on the previous study on the TDC, we developed the gain tuning method for the SMCTE, which results were nearly the same as the TDC. With respect to the step response, the SMCTE proved its predominance in a comparison with other control schemes such as the PID control and the relay control. As well as the contribution of the above control methodology, the model identification for SMA actuators has also been studied. The dynamics for an SMA actuator was newly derived using the modified Liang's model. The derived dynamics showed a continuity at the change of the phase transformation process but the original Liang's model could not.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.572-575
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• 2005

A novel pneumatic artificial muscle actuator (PAM actuator), which has achieved increased popularity to provide the advantages such as high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks, has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators. In order to realize satisfactory control performance, a variable damper Magneto Rheological Brake (MRB), Is equipped to the Joint of the manipulator. Superb mixture of conventional PID controller and a phase plane switching control method brings us a novel controller. This proposed controller is appropriate for a kind of plants with nonlinearity, uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control method and without regard for the changes of external inertia loads.

• Smart Structures and Systems
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• v.14 no.3
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• pp.347-365
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• 2014

The main objective of this paper is to develop an innovative methodology for the vibration suppression control of the multiple degrees-of-freedom (MDOF) flexible structure. The proposed structure represented in this research as a clamped-free-free-free truss type plate is rotated by motors. The controller has two loops for tracking and vibration suppression. In addition to stabilizing the actual system, the proposed feedback control is based on a genetic algorithm (GA) to seek the primary optimal control gain for tracking and stabilization purposes. Moreover, input shaping is introduced for the control scheme that limits motion-induced elastic vibration by shaping the reference command. Experimental results are presented, demonstrating that, in the control loop, roll and yaw angles track control and elastic mode stabilization. It was also demonstrated that combining the input shaper with the proportional-integral-derivative (PID) feedback method has been shown to yield improved performance in controlling the flexible structure system. The broad range of problems discussed in this research is valuable in civil, mechanical, and aerospace engineering for flexible structures with MDOM motion.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.182-189
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• 2014

This paper proposes a decoupler design method to reduce interaction between exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems in passenger car diesel engines. The EGR valve and VGT vane are respectively used to control air-to-fuel ratio (AFR) of exhaust gas and intake pressure. A plant model for EGR and VGT systems is defined by a first order transfer function plus time-delay model, and the loop interaction between these systems is analyzed using a relative normalized gain array (RNGA) method. In order to deal with the loop interaction, a design method for simplified decoupler is applied to this study. Feedback control algorithms for AFR and intake pressure are composed of a compensator using PID control method and a prefilter. The proposed decoupler is evaluated through engine experiment, and the results successfully showed that the loop interaction between EGR and VGT systems can be reduced by using the proposed decoupler. Furthermore, it presents stable performance even off from the designed operating point.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.8
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• pp.833-842
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• 2011

The objectives of this research are development of guidance, navigation and control system for RUAV on virtual instrumentation and real flight test. For this research, the system is divided to DAQ (data acquisition) section, actuator section and controller section. And the hardware and software on each sections are realized on LabVIEW base. Waypoint guidance and control of auto flight are realized using PID gain tuning and waypoint vector tracking guidance algorism. For safe flight test, auto/manual switching module isolated from FCS (Flight Control System) is developed. By using the switch module, swift mode change was achieved during emergency flight case. Consequently, a meter level error of flight performance is achieved.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.12
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• pp.1101-1105
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• 2012

This study proposes a method for improvement of PD type fuzzy controller. The method includes self tuner using gradient algorithm that is one of the optimization algorithms. The proposed controller improves simple Takagi-Sugeno type FLC (Fuzzy Logic Control) system. The simple Takagi-Sugeno type FLC system changes nonlinear characteristic to linear parameters of consequent membership function. The simple FLC system could control the system by calibrating parameter of consequent membership function that changes the system response. While the determination on parameter of the simple FLC system works well only partially, the proposed method is needed to determine parameters that work for overall response. The simple FLC system doesn't predict the response characteristics. While the simple FLC system works just like proportional part of PID, our system includes derivative part to predict the next response. The proposed controller is constructed with P part and D part FLC system that characteristic parameter on system response is changed by self tuner for effective response. Since the proposed controller doesn't include integral part, it can't eliminate steady state error. So we include a gain to eliminate the steady state error.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.05a
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• pp.199-206
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• 1995

200kW급 가스엔진 열병합시스템에서 엔진 냉각수는 엔진을 냉각시키는 기능 뿐아니라 배열회수용 열원으로 사용된다. 전력부하나 냉·난방 부하가 변할 때 엔진 냉각수의 온도가 민감하게 변하므로 이를 일정하게 제어하기 위하여 PID 제어기를 사용하고 있다. 본 연구는 이 제어기의 적정 이득값(gain)을 설정하기 위하여 공정 전달함수를 실험적방법을 이용하여 일차시간지연함수(First Order Plus Dead Time)로 근사한 후 여러 조율방법을 사용하여 이득값을 구하였다. 이 이득값과 전달함수를 가지고 공정모사기인 “MATLAB”을 사용하여 시스템에 적합한 적정이득값을 선정 하였으며 실증실험 결과 시스템의 온도동특성이 안정됨을 보였다.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.151-159
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• 2008

The parameter-based cardiovascular impedance simulator that is able to overcome the limits of conventional mock circulatory systems is critical for the development and test of biomedical devices including artificial heart. The concept of impedance simulator was validated mathematically in a previous study using high-gain feedback linearization control which, however, may cause serious difficulties and limits for practical implementation. In this study, therefore, practical applicability of the impedance simulator is investigated considering the physical limits such as motor speed and torque. Simple PID controller which do not require complex model of the simulator is used considering the practical implementation. Design guidelines of the impedance simulator are also provided based on the results.