• Proceedings of the Korea Society for Simulation Conference
• /
• 2000.04a
• /
• pp.180-185
• /
• 2000

발전소 등의 대규모 공정 플랜트에서 사용하고 있는 대부분의 상용 제어기는 PID 제어기이며, 온도 루프를 제외한 대부분의 제어루프가 PI 제어기를 채용하고 있다. 제어 시스템의 성능이 제어기 파라미터의 값에 의해 결정되므로, PI 제어기의 튜닝이 중요하다. 한편, 실제 현장에서의 PI 제어기의 튜닝은 많은 시간과 노력을 필요로 하는 시행착오에 의해서 이루어지고 있으며, 각 제어 루프 제어기 파라미터의 초기값 설정에 어려움을 갖고 있는 실정이다. PI 튜닝 기법이 많이 나와 있지만 시험 신호의 인가 문제로 인해 현장 활용에는 많은 어려움을 가지고 있다. 본 논문에서는 단순한 시험 신호로부터 PI 초기 설정값을 산출할 수 있는 방법에 대해서 알아본다. 또한 발전소에 적용된 국산 분산 제어 시스템을 보면, 대부분 데이터 로깅 시스템으로서만 활용되고 있고, 제어 시스템으로의 활용은 거의 이루어지지 않고 있으며, PID제어기에 대한 구현도 완벽하지 못하여 디지털 PI 제어기의구현 방법에 대한 고찰도 요구되고 있다. 본 논문에서는 디지탈 PI 제어기를 구현하는데 있어서 필요한 사항들, 즉 아날로그 제어기의 디지털 등가 제어기로의 변환 기법, 샘플링 주기의 결정 방법, 그리고 그 외에 공정 제어기가 가져야할 기능들에 대해서 언급한다. 그리고나서 PI 튜닝 기법과 아날로그 제어기의 디지털 등가 제어기로의 변환기법, 샘플링 주기 결정 방법 등에 대해 플랜트 모델을 선정하고 시뮬레이션을 통해 그 효용성을 보인다.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.5
• /
• pp.525-529
• /
• 2009

Most of FLC received input data from error e and change-of-error e' with no relation with system complexity. Basic scheme follows typical PD and PI or PID Controller and that has been developed through fixed ME In this paper, We studied the relationship between MF and system response and system response through changing Fuzzy variable of consequence MF and propose the simple FLC using this relationship. The response of FLC is changed according to the width of Fuzzy variable of consequence MF. As changing the Fuzzy variable of consequence MF shows various nonlinear characteristic, we studied the relation between response and MF using analytical method. We designed the effective FLC using three-variable MF and nine rules and took simulation for verification. In this study, we propose the method to design system with FLC in stability point which is an impotent characteristic of designing system. The circle criterion which is adapted to analysis the nonlinear system is put to use for proposed method. Since SISO FLC has a time-invariant and odd characteristic we can use the critical point not disk which is generally used to determine the stability in the circle criterion, to determine the stability. Using this, we can get the maximum critical point plot of SISO FLC with changing the consequence fuzzy variables. The predetermined critical point plot of FLC can be used to decide the region of the system to be stable. This method is effectively used to design the SISO FLC.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2018.10a
• /
• pp.434-437
• /
• 2018

본 논문에서는 ROS (Robot Operating System)에 대해서 소개하고 ROS를 이용해 드론의 제어기와 필터를 구현해본다. 드론이 강인한 성능을 보이기 위해서는 기체의 상태에 대한 더 정확한 추정이 필요하다. 드론이 기체좌표계로 출력하는 각 축(x축, y축, z축)에 대한 선속도, 선가속도를 더 정확히 추정하기 위해 칼만 필터를 설계하며 칼만 필터를 통과한 상태 변수를 제어 입력으로 하는 PID(Proportional Integral Derivative) 제어기를 설계한다. 실험적인 부분에서는 제어기와 자율 주행 알고리즘을 접목시켜 드론이 자신의 상태를 추정하고 알고리즘을 순차적으로 진행하는 과정을 살펴본다. 마지막으로 알고리즘을 통해 드론의 임무 수행 여부를 살펴보고 정밀한 제어를 위한 추가적인 제어기 설계 방법과 연구 방향을 제시하고자 한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.08a
• /
• pp.41-46
• /
• 2002

본 논문은 냉, 난방 디지털 온도 조절계(SPC 50)의 Etl의 편차 정 동작에 관한 구현장치 제작과 비례 미.적분기가 At 및 비 At기능에서 설정온도를 $100^{\circ}C$를 유지하는데 기인된 전압전류 및 전력데이터 획득의 요인과 비례미적분 정수 및 노 개선점을 연구하였다. 설정온도를 유지하는 온도변화는 At기능에서 $96.7^{\circ}C\sim102^{\circ}C$ 이며, 비At 기능에서는 $97.6^{\circ}C\sim100.2^{\circ}C$이었다. 온도유지 전압변동은 At기능에서 2V~217V이며, 비 At기능에서 20V~217V 이었다. At와 비 At 기능에서 설정온도 $100^{\circ}C$을 유지하는데 온도를 냉각시키는 환풍기가 온. 오프 되는 시간차는 20초 정도 발생하였다. 온도차 및 전압차는 두 기능간에 비례 미. 적분값 설정이 자동 및 수동이냐에 따라서 차이를 보여주었다. 두 기능에서 설정된 온도값 유지에 따른 전압전류의 승압과 하강의 변동된 변환 데이터는 설정된 온도가 성취되어지는 시간차 및 설정값 유지의 특성을 요인으로 한 PID값과 노의 개선점에 길잡이가 된다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.9
• /
• pp.1065-1071
• /
• 2012

Wind energy is becoming one of the most preferable alternatives to conventional sources of electric power that rely on fossil fuels. For stable electric power generation, constant rotating speed control of a wind turbine is performed through pitch control and stall control of the turbine blades. Recently, variable pitch control has been implemented in modern wind turbines to harvest more energy at variable wind speeds that are even lower than the rated one. Although wind turbine pitch controllers are currently optimized using a step response via the Ziegler-Nichols auto-tuning process, this approach does not satisfy the requirements of variable pitch control. In this study, the variable pitch controller was optimized by a genetic algorithm using a neural network model that was constructed by the Latin Hypercube sampling method to improve the Ziegler-Nichols auto-tuning process. The optimized solution shows that the root mean square error, rise time, and settle time are respectively improved by more than 7.64%, 15.8%, and 15.3% compared with the corresponding initial solutions obtained by the Ziegler-Nichols auto-tuning process.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.41 no.6
• /
• pp.67-74
• /
• 2004

Differently from an existing analog control, because the digital control includes microprocessor basically, the digital control is enable to monitor internal parameters of DC-DC converter and to control output voltage remotely by communicating with a Windows based PC. These things are impossible in an analog control and there are more advantages in a digital control than an analog control. In this paper, with the advantages mentioned above, the feasibility of digital controlled DC-DC converter in low price is proposed. In order to implement these functions, it is used the inexpensive H8/3672 made by Renesas that has built in AD converters and PWM logic generators. The proposed digital controller is applied to a flyback converter that is designed to output DC 5[V] from DC 20∼30[V] and is remotely controlled to make variable outputs from DC 0[V] to 5[V] above in PC. The PWM controller adopts the PD controller in PID. In the last, the response characteristics of a step reference voltage and in a steady state are experimented to verify the feasibility and the usefulness of the proposed flyback converter that is implemented inexpensively.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.2508-2513
• /
• 2003

This paper presents a nuclear steam generator tube inspection/maintenance robot system. The robot assists in automatic non-destructive testing and the repair of nuclear steam generator tubes welded into a thick tube sheet that caps a hemispherical or quarter-sphere plenum which is a high-radiation area. For easy carriage and installation, the robot system consists of three separable parts: a manipulator, a water-chamber entering and leaving device for the manipulator and a manipulator base pose adjusting device. A software program to control and manage the robotic system has been developed on the NT based OS to increase the usability. The software program provides a robot installation function, a robot calibration function, a managing and arranging function for the eddy-current test, a real time 3-D graphic simulation function which offers remote reality to operators and so on. The image information acquired from the camera attached to the end-effecter is used to calibrate the end-effecter pose error and the time-delayed control algorithm is applied to calculate the optimal PID gain of the position controller. The developed robotic system has been tested in the Ulchin NPP type steam generator mockup in a laboratory.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.3
• /
• pp.88-97
• /
• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.475-478
• /
• 2004

In this paper, a magnet-type automatic pipe cutting machine that binds itself to the surface of the pipe using magnetic force and executes unmanned cutting process is proposed. During pipe cutting process when the machine moves around the pipe laid vertical to the gravitational field, the gravity acting on the pipe cutting machine widely varies as the position of the machine varies. That is, with same driving force from the driving motor the cutting machine moves faster when it climbs down the surface of the pipe and moves slower when it climbs up to the top of the pipe. To maintain a constant velocity of the pipe cutting machine and improve the cutting quality, the authors adopted a conventional PID controller with a feedforward effort designed based on the encoder measurement of the driving motor. It is, however, impossible for the encoder at the motor to measure the absolute position and consequently the absolute velocity of the cutting machine in the case where the slip between the surface of the pipe and wheel of the cutting machine is not negligible. As an attempt to obtain a better estimation of the absolution angular position/velocity of the machine the authors proposes the use of the MEMS-type accelerometer which can measure static acceleration as well as dynamic acceleration. The estimated angular velocity of the cutting machine using the MEMS-type accelerometer measurement is experimentally obtained and it indicates the significant slipping of the machine during the cutting process.

• Ocean Systems Engineering
• /
• v.6 no.3
• /
• pp.265-287
• /
• 2016

The change of the global performance of a turret-moored FPSO (Floating Production Storage Offloading) with DP (Dynamic Positioning) control is simulated, analyzed, and compared for two different internal turret location cases; bow and midship. Both collinear and non-collinear 100-yr GOM (Gulf of Mexico) storm environments and three cases (mooring-only, with DP position control, with DP position+heading control) are considered. The horizontal trajectory, 6DOF (degree of freedom) motions, fairlead mooring and riser tension, and fuel consumptions are compared. The PID (Proportional-Integral-Derivative) controller based on LQR (linear quadratic regulator) theory and the thrust-allocation algorithm which is based on the penalty optimization theory are implemented in the fully-coupled time-domain hull-mooring-riser-DP simulation program. Both in collinear and non-collinear 100-yr WWC (wind-wave-current) environments, the advantage of mid-ship turret is demonstrated by the significant reduction in heave at the turret location due to the minimal coupling with pitch mode, which is beneficial to mooring and riser design. However, in the non-collinear WWC environment, the mid-turret case exhibits unfavorable weathervaning characteristics, which can be reduced by employing DP position and heading controls as demonstrated in the present case studies. The present study also reveals the plausible cause of the failure of mid-turret Gryphon Alpha FPSO in milder environment than its survival condition.