• Journal of Power System Engineering
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• v.14 no.1
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• pp.65-70
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• 2010

Magnetic levitation system is nonlinear and inherently unstable, so it is difficult to control. Analog control circuit was widly used as the controller of magnetic levitation system, but digital controller is now substituted for analog controller according to development of digital electronics. In this study, Atmel AVR series, ATmega 128 which is a kind of $\mu$-processor for digital controller is used because the chip is cheap and popular. We designed and made ATmega 128 one-board controller and aimed to verify validity through the experiance of levitation response.

• Journal of Drive and Control
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• v.9 no.4
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• pp.58-61
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• 2012

The customers who used the hydroulic system desire the product that has more detailed specification quickly during the industrial technology is developed. Every researcher try to reduce the developed period and to satisfy the customers' desire. Lot's of simulation software and hardware already was used to be satisfied those purpose. But these kind of equipment need a lot of cost to set up and technical knowledge to drive that system. This paper concerns about analog PID controller that can be assembled with a few resistor, condenser and optional amplifier and doesn't need technical knowledge to drive. At the first, the plant was modeled mathematically to design the analog PID controller's circuit. After that, PID controller's parameter was selected by customers' desire. Finally, the analog PID controller's circuit was assembled from the control law. The circuit's availability was confirmed by step response test in the controlled system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.96-101
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• 1998

많은 분야에서 널리 사용되고 있는 PID 제어기의 형태는 오차를 갖는 폐루프 시스템으로 구성되며, PID 제어기는 비례, 적분, 미분 제어기로 나누어진다. PID 제어기의 형태가 여러 가지로 제안되고 있지만 보다 중요한 것은 PID 제어기의 파라미터들을 어떻게 적절히 정하느냐 하는 파라미터 조정 문제이다. 실제로 산업 현장에 설치되어 있는 PID 제어기는 대부분 숙련된 기술자에 의해 수동 조작에 의한 시행 착오(trial and error) 법으로 동조되고 있다. 이 경우는 많은 노력과 시간이 소비되고, 외란(disturbance)이 첨가될 경우 적절히 동조된다는 보장도 없다. 본 논문에서는 이러한 문제를 해결하고자 신경회로망을 이용하여 PID 제어기의 파라미터를 동조하는 제어 방법을 제안하였다. 단일 뉴런으로 구성하여 구조가 간단하고, 학습에 의한 성능 개선이 가능하다. 오차 역전파(Error Back-Propagation) 알고리즘에 의하여 PID 파라미터가 되는 가중치를 자동 동조하는 방법이다. 제안한 방식의 유용성을 보이기 위해 DC 서보 모터와 비선형 시스템인 단일 관절 매니퓰레이터를 대상으로 시뮬레이션을 하였다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.165-168
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• 2001

본 논문은 비선형 헬리콥터 시스템의 퍼지 비례-적분-미분 (PID) 제어기의 설계기법을 제안한다. 퍼지 제어기는 풍부한 자유도를 포함하므로 비선형 시스템의 제어에 매우 적합하다. 그러나 이의 설계는 전문가의 지식에 의존하므로 시스템의 정확한 지식의 획득에 어려울 경우 우수한 성능을 보장하는 제어기의 설계가 매우 어렵다. 따라서 본 논문에서는 제안된 퍼지 PID 제어기의 성능 향상 및 최적화를 위하여 전역적 비선형 최적화 기법인 유전 알고리듬 (GA)을 도입한다. 본 논문에서 제안한 퍼지 PID 제어기의 설계기법은 실제 비선형 헬리콥터 실험 장치에 적용하여 그 효용성 및 실제 산업분야에의 응용 가능성을 보인다.

• Journal of Drive and Control
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• v.13 no.3
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• pp.15-23
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• 2016

The direct-drive servo valve(DDV) is a kind of one-stage valve because the main spool valve is directly driven by the dc motor. Since the DDV structure is simple, it is less expensive, more reliable, and offers a reduced internal leakage and a reduced sensitivity to fluid contamination. The control system of the DDV is highly nonlinear due to a current limiter, a voltage limiter, and the flow-force effect on the spool motion. The shape of the step response of the DDV-control system varies considerably according to the magnitudes of the step input and the load pressure. The system-design requirements mean that the overshoots should be less than 20%, and the errors at 0.02s should be less than 2%, regardless of the reference-step input sizes of 1V and 5V and the load-pressure magnitudes of 0MPa and 20.7MPa. To satisfy the system-design requirements, the PID-controller parameters of $K_c$, $T_i$ and $T_d$, and the derivative-feedback gain of $K_{der}$ are designed using the root locus and manual tuning.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.5
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• pp.609-616
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• 2003

The purpose of this study is to design the adaptive speed control system of a marine diesel engine by combining the Model Matching Method and the Nominal Model Tracking Method. The authors proposed already a new method to determine efficiently the PID control Parameters by the Model Matching Method. typically taking a marine diesel engine as a non-oscillatory second-order system. But. actually it is very difficult to find out the exact model of a diesel engine. Therefore, when diesel engine model and actual diesel engine are unmatched as an another approach to promote the speed control characteristics of a marine diesel engine, this paper Proposes a Model Reference Adaptive Speed Control system of a diesel engine, in which PID control system for the model of a diesel engine is adopted as the nominal model and Fuzzy controller and derivative operator are adopted as the adaptive controller.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1450-1454
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• 2005

In this paper, the control strategy of the tension and speed based a prototype bio-wrap winding machine is developed. The decentralized control strategy using PID control algorithm applied for each subsystem is proposed to control the each system's desired outputs, because the tension of each subsystem effects that of next roll system. The computer simulations and the experiment results are presented to show that the proposed control scheme is feasible for a prototype bio-wrap winding machine.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.4
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• pp.87-94
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• 2004

Recently, technical trend in machine tools is focused on enhancing of speed, accuracy and reliability. The high speed usually results in thermal displacement and structural deformation. To minimize the thermal effect, precision machine tools adopt a high precision cooling system. This study proposes a temperature control for an oil cooler system using Pill control with fuzzy logic. In the cooler system, refrigerant flow rate is controlled by rotational speed of a compressor, and outlet oil temperature is selected as the control variable. The fuzzy control rules iteratively correct PID parameters to minimize the error and difference between the outlet temperature and the reference temperature. Here, ambient temperature is used as the reference one. To show the effectiveness of the proposed method, a series of experiments are conducted for an oil cooler system of machine tools, and the results are compared with the ones of a conventional Pill control. The experimental results show that the proposed method has advantages of faster response and smaller overshoot.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.452-454
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• 2008

본 논문에서는 실험적으로 구한 엔진 토크 참조 표를 이용하여 엔진의 비선형 모델을 구하고 이를 각각의 운전 점에 대해 선형화한 엔진 모델을 제시하였다. 이러한 선형화된 엔진 모델을 이용하여, 전기식 조속기를 사용한 디젤 엔진의 속도 제어에 있어 발생하는 안정성 문제를 해석하였다. 제시한 디젤 엔진 모델을 이용하여 속도제어기의 비례, 적분 미분 이득을 설정하고 이 값을 바탕으로 모의실험 및 실험을 통하여 제시한 모델의 타당성을 검증 하였다.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.106-112
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• 2000

The purpose of this paper is to study on the control of the engine idle speed under sudden A/C load which is one of the most severe disturbances on engines. Three types of the closed-loop controller are developed for the stable engine idle speed control. The input of the controller is an error of rpm. The output of the controller is an ISCV duty cycle. The anticipation delay is considered to deal with the delay time of the air mass in engine. The PID, Fuzzy and PID-type Fuzzy controllers with the anticipation delay have improved the engine idle speed condition more than current ECU map table under the A/C load.