• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.864-867
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• 2003

In this study, a controller which has a feedforward controller and two additional PI integrators was designed. But if a controller is used by only the integration of a feedforward controller and two additional PI integrators, the capability of a controller will decrease because the decoupling terms of current is feedback as the disturbance. Therefore the feedforward method with the decoupling compensation was proposed. The two additional PI integrators were replaced by two decoupling terms to simplify the calculation. The simulation and experimental using SynRM driving system were performed to verify the design of a improved decoupling feedforward controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.261-266
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• 1995

본 연구에서는 자기부상시스템에 대해 흡인식 자기부상방식을 채택하고 쇠구슬에 대한 운동을 상하 1자유도로 가정하여 운동방정식을 세운다. 이때 전자석이 자기 부상력은 전자석에 흐르는 전류와 인덕턴스의 함수라 가정하고, 모델의 불확실성은 자기부상계의 운동 방정식으로부터 선형화 할 때 발생하는 오차 및 파라미터 변동으로 생각한다. 또한 모델의 불확실성이 존재하더라도 정상편차 없이 부상하는 서보제어계를 설계한다. 그런데 저자등은 강인성 문제 및 정상편차 없는 것에 역점을 두어 H$_{\infty}$ 제어이론에 기초한 1형 로바스트 서보 제어기를 구하여 자기부상 시스템의 안정화 제어계로써 적용한 적이 있다. 이때 중심해 이외의 해를 이용하여 설계한 서보 제어계는 자기부상계의 과도상태시에 일어나는 오버슈트를 줄일 수 없었다. 따라서 시스템 내부 안정화를 위하여 H$_{\infty}$ 제어이론에 의해 설계된 피드백(feedback) 제어기와 물체가 부상할 때 오버슈트를 줄이고 제어량이 목표치에 잘 추종하기 위해 설계된 피드 포워드(feed forward) 제어기로써 2자유도를 갖는 제어계를 설계한다. 이렇게 설계한 2자유도 제어계를 가지고 모의 응답실험과 본 연구자들이 만든 자기부상 시스템의 실험결과를 비교함으로써 설계된 제어기의 타당성을 조사한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.135-146
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• 2013

This paper presents a feedforward control algorithm for the EGR and VGT systems of passenger car diesel engines. The air-to-fuel ratio and boost pressure are selected as control indicators and the positions of EGR valve and VGT vane are used as control inputs of the EGR and VGT controller. In order to compensate the non-linearity and coupled dynamics of the EGR and VGT systems, we have proposed a non-linear model-based feedforward control algorithm which is obtained from static model inversion approach. It is observed that the average modeling errors of the feedforward algorithm is about 2% using stationary engine experiment data of 225 operating conditions. Using a feedback controller including proportional-integral, the modeling error is compensated. Furthermore, it is validated that the proposed feedforward algorithm generates physically acceptable trajectories of the actuator and successfully tracks the desired values through engine experiments.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.406-408
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• 2006

본 논문은 플라즈마 디스플레이 패널(PDP) 전원공급 장치로 사용되는 DC-DC 컨버터의 동적 응답특성을 향상 시킬 수 있는 새로운 디지털 제어 알고리즘을 서술한다. 제안하는 알고리즘은 PDP에 영상을 표시하기 위한 영상 입력신호와 구동회로의 유지방전 파형의 제어를 위한 신호를 이용하여 부하전류의 변화량과 시점을 예측한다. 별도의 추가적인 전류센서를 사용하지 않고 예측된 부하전류 정보는 일반적인 디지털 전압 제어기에 피드포$\sim$워드 형태로 추가되어 적용된다. 제안된 알고리즘은 디지털 Pl 전압 제어기만을 사용한 경우에 비해 부하전류가 급격히 변동할 때 좀 더 빠른 응답특성과 낮은 출력전압 변동 특성을 보인다. 제안된 알고리즘은 FPGA를 사용하여 구현 되었으며, Buck 컨버터를 사용하여 기본 동작을 검증하였다.

• Journal of Internet Computing and Services
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• v.20 no.5
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• pp.95-104
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• 2019

Various kinds of devices are used for the Internet of Things (IoT) service, and IoT devices mainly use communication technology that uses the frequency of the unlicensed band. There are several types of communication technology in the unlicensed band, but WiFi is most commonly used. Devices used for IoT services vary in computing resources from devices with limited capabilities to smartphones and provide services over wireless networks such as WiFi. Most IoT devices can't perform complex operations for network control, thus they choose a WiFi access point (AP) based on signal strength. This causes a decrease in IoT service efficiency. In this paper, an intelligent AP system that can efficiently control the WiFi connection of the IoT devices is implemented. Based on the network information measured by the IoT device, the access point learns using a feed forward neural network algorithm, and predicts a network connection state to control the WiFi connection. By controlling the WiFi connection at the AP, the service efficiency of the IoT device can be improved.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.174-181
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• 1997

A proposed hybrid self-tuning control scheme for single rod hydraulic cylinder which has varying loads is presented here. An adaptive controller is developed for the system that use feedforward and P feedback control for simultaneous parameter identification and tracking control. Through experimental results, the performance comparison of the hybrid self-tuning controller with a constant gain P contro- ller clearly shows its superior ability in handling load changes in quiescent states.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1122-1127
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• 2001

This paper proposed a speed adaptive control system with load torque observer and feed-forward compensation using neural network for air compressor system driven an induction motor. The motor receive impact load change under the influence of piston movement of up and down, and so it difficult to obtain good speed control characteristics. With real-time adjusting control gain estimated in neural network, control characteristics of motor is improved. The validity of the proposed system is confirmed through the theoretical analysis and computer simulation.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.1064-1065
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• 2017

트레드밀 인터페이스는 사용자의 보행 모션을 인식하여 가상세계를 네비게이션 할 수 있는 보행 플랫폼이다. 특히 작은 보행 영역을 가지는 트레드밀의 경우, 보행자 속도 예측 방법에 의해 더욱 효과적인 지면 모션의 생성이 가능하다. 본 연구에서는 착용형 압력 센서로 부터 측정되는 족부 압력 데이터를 기반으로 하는 보행속도 예측 방법과 트레드밀 제어 방법을 제시하고자 한다. 속도 예측은 지면 반발력 데이터 중 압력중심의 변화 속도를 통해 도출되며, 예측된 속도를 트레드밀 속도 제어에 안정적으로 적용하기 위한 피드포워드 제어 방법을 제시한다. 또한 족부 압력 데이터 측정이 가능한 자율 제어 트레드밀 시스템 구현과 보행 실험 과정을 소개한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.4
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• pp.233-241
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• 2001

In the present study, various experiments were performed to investigate the capacity modulation and transient response control using a variable speed compressor and electronic expansion valve(EEV). Based on the experimental results, the operation control algorithm and real time digital control system were constructed to adjust the superheat at the inlet of the compressor. Superheat control was fulfilled using both the PI feedback controller and PI controller combined with a feedforward concept. As a result, the tracking performance of the latter was better than that of former.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.3
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• pp.1-6
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• 2010

This paper deals with the issue of simple adaptive position control for a pump-controlled cylinder system. A fixed displacement pump is utilized instead of servo valve and its speed is controlled by AC motor. The whole control system is composed of a pair of interconnected subsystems, that is, a feedback control system and a feedforward control system. From experiments it is shown that position control using simple adaptive control can accomplish significant reduction in position tracking error comparing to a conventional PID control.