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류정래(Jung Rae Ryoo),도태용(Tae-Yong Doh) 제어로봇시스템학회 2014 제어·로봇·시스템학회 논문지 Vol.20 No.2
DC motor is a representative electric motor commonly utilized in various motion control fields. However, DC motor-based motion control systems suffer from degradation of position precision due to nonlinear static friction. In order to enhance control precision, friction model-based compensators have been introduced in previous researches, where friction models are identified and counter inputs are added to control inputs for cancelling out the identified friction forces. In this paper, a static friction compensator is proposed without use of a friction model. The proposed compensation algorithm utilizes internal state manipulation to generate compensation pulses, and related parameters are easily tuned experimentally. The proposed friction compensator is applied to a DC motor-based motion control system, and results are presented in comparison with those without a friction compensator.
류정래(Jung Rae Ryoo),도태용(Tae-Yong Doh) 제어로봇시스템학회 2014 제어·로봇·시스템학회 논문지 Vol.20 No.5
Optical pick-up is a core component for data read/write operations in optical disc drives, and an optical pick-up performance evaluator is an instrument used to analyze the overall performance of an optical pick-up. Due to inevitable errors in an analog measurement circuit, resultant evaluation data is not guaranteed to be accurate. In this paper, a calibration method for an optical pick-up performance evaluator is proposed to ensure evaluation accuracy. Measured data is corrected by a 1st order correction function, and a calibration process based on least-square method is utilized to obtain correction coefficients of the correction function. The proposed calibration method is applied to experiments, and enhanced accuracy is presented with resultant evaluation data.
1/4 차량 현가 장치의 강인 안정성을 보장하는 외란관측기 기반의 제어 시스템 설계
소상균(Sang Gyun So),류정래(Jung Rae Ryoo),도태용(Tae-Yong Doh) 제어로봇시스템학회 2016 제어·로봇·시스템학회 논문지 Vol.22 No.12
The vehicle suspension system plays a very important part related with vehicle ride and handling. To improve the vehicle ride and handling many researches have been progressed from various damping parameter tuning techniques to the development of the electronic controlled suspension systems. In this paper, as one of the ride performance improvement a disturbance observer(DOB) based control system is applied to the quarter car vehicle model in order to show that the DOB can obtain good vibration isolation characteristics. First, the robust stability criterion for the DOB is introduced in detail, and then how DOB is applied to the 1/4 car vehicle model is represented, and finally to confirm the effectiveness of the DOB in vehicle ride performance improvement a computer simulation is carried out for various driving conditions.
최용준(Yong Joon Choi),류정래(Jung Rae Ryoo),도태용(Tae-Yong Doh) 제어로봇시스템학회 2014 제어·로봇·시스템학회 논문지 Vol.20 No.9
In this paper, a new steering system for a self-balancing electric scooter is proposed with an intuitive steering command input method, where the steering command is generated from the rider’s motion of shifting body to move the center of gravity toward the rotational direction. For the purpose, weight distributions on the rider’s feet are measured using force sensors placed beneath the rider’s feet, and the difference is applied to a steering control system. Stability of the steering system and resultant radius of gyration is investigated by modeling the steering system in consideration of the rider’s motion and centrifugal force. The proposed steering system is applied to experiments, and the results are presented to prove the validity of the proposed method.
최용준(Yong Joon Choi),류정래(Jung Rae Ryoo) 대한전자공학회 2016 전자공학회논문지 Vol.53 No.6
FPGA 기반 실시간 영상 워핑 시스템에서는 영상 픽셀 정보의 빠른 읽기와 메모리 접근 횟수의 감소를 위하여 영상 캐시를 활용하지만, 일반 컴퓨터 시스템의 캐시 알고리즘은 캐시 부적중(cache miss)에 의한 시간 지연과 복잡한 온라인(on-line) 연산 구조로 인하여 실시간 성능 구현에 어려움이 있다. 본 논문에서는 FPGA 기반 실시간 영상 워핑을 위한 단순한 구조의 영상 캐시 알고리즘을 제안한다. 영상 워핑에서의 픽셀 데이터 접근 순서는 워핑에 적용할 2D 좌표변환 관계에 의하여 결정되며 매 영상 프레임에서 반복되는 특성이 있다. 따라서, 캐시 로드(cache load)에 관한 사항을 오프라인(off-line)에서 미리 프로그램함으로써 캐시 부적중 상황이 발생하지 않음을 보장할 수 있고, 그 결과 온라인에서의 연산이 감소하여 캐시 컨트롤러의 구조가 단순해진다. FPGA를 활용한 전체 시스템 구조를 제시하고, 실험을 통하여 제안하는 영상 캐시 알고리즘의 정확성과 타당성을 확인한다. In FPGA-based real-time image warping systems, image caches are utilized for fast readout of image pixel data and reduction of memory access rate. However, a cache algorithm for a general computer system is not suitable for real-time performance because of time delays from cache misses and on-line computation complexity. In this paper, a simple image cache algorithm is presented for a FPGA-based real-time image warping system. Considering that pixel data access sequence is determined from the 2D coordinate transformation and repeated identically at every image frame, a cache load sequence is off-line programmed to guarantee no cache miss condition, and reduced on-line computation results in a simple cache controller. An overall system structure using a FPGA is presented, and experimental results are provided to show accuracy and validity of the proposed cache algorithm.
쿼드로터 헤딩 방향 제어를 위한 지자기 센서 보상 및 센서 융합
이유진(You Jin Lee),류정래(Jung Rae Ryoo) 대한전자공학회 2016 전자공학회논문지 Vol.53 No.7
쿼드로터의 헤딩 방향 감지를 위하여 일반적으로 활용하는 지자기 센서에서는 주변 자기 간섭 및 롤/피치 축 기울기로 인한 오차가 발생한다. 본 논문에서는 쿼드로터 헤딩 방향 제어를 위하여 지자기 센서와 자이로 센서의 측정 결과를 융합하는 방위각 측정 방법을 제안한다. 롤/피치 축 방향 회전으로 인하여 발생하는 지자기 센서의 좌표축 변화를 분석하고, 수평 자세 제어를 목적으로 측정된 롤/피치 축 각도를 활용하여 지자기 센서의 기울기 보상을 적용한다. 또한, 요 축 각도 측정에 상보필터를 활용하여 지자기 센서의 요 축 각도와 자이로스코프 센서의 요 축 방향 각속도 데이터를 융합한다. 제안한 방식을 실험에 적용하고 결과를 제시하여 요 축 각도 측정의 타당성 및 효과를 검증한다. Geomagnetic sensors are widely utilized for sensing heading direction of quadrotors. However, measurement from a geomagnetic sensor is easily corrupted by environmental magnetic field interference and roll/pitch directional motion. In this paper, a measurement method of a quadrotor heading direction is proposed for application to yaw attitude control. In order to eliminate roll/pitch directional motion effect, the geomagnetic sensor data is compensated using the roll/pitch angles measured for stabilization control. In addition, yaw-directional angular velocity data from a gyroscope sensor is fused with the geomagnetic sensor data using a complementary filter which is a simple and intuitive sensor fusion method. The proposed method is applied to experiments, and the results are presented to prove validity and effectiveness of the proposed method.
실시간 고해상도 컬러 영상 워핑을 위한 FPGA 기반 하드웨어 설계
이유진(You Jin Lee),류정래(Jung Rae Ryoo) 대한전자공학회 2021 전자공학회논문지 Vol.58 No.2
본 논문에서는 고해상도 컬러 영상 워핑의 실시간 처리를 위한 FPGA 기반 하드웨어를 설계한다. 영상 워핑은 입력 영상에 2D 좌표 변환을 적용하는 영상 처리 알고리즘으로 실시간 영상 워핑 구현을 위해서는 좌표 변환 연산, 픽셀 데이터 보간 연산, 그리고 고속 영상 버퍼 메모리 구조 등 3가지 문제에서 실시간 성능 및 정확성을 확보하여야 한다. 본 논문에서는 CFA 컬러 영상 워핑을 활용한 연산량 감소, 오프라인 캐시 스케줄링 및 캐시 메모리 분할 구조를 적용한 영상 데이터 캐시, 그리고 연산의 선후 관계 및 타이밍 조건을 고려한 병렬 처리 및 파이프라인 구조 등을 통하여 실시간 동작 성능을 확보한다. Full HD 해상도의 컬러 영상 입력에 대한 구현된 시스템의 동작 정확성을 PC 소프트웨어의 처리 결과와 비교/확인하고, 실시간 렌즈 왜곡 보정에 적용하여 구현된 시스템의 타당성을 검증한다. This paper presents a design of an FPGA-based hardware for real-time high-resolution color image warping. Image warping is an image processing algorithm applying 2D coordinate transformation to an input image. For real-time processing of image warping, real-time performance and accuracy are required in the following 3 problems, such as, computation of coordinate transformation, interpolation of pixel data, and fast image buffer memory structure. In this paper, real-time performance is guaranteed by the computationally efficient CFA color image warping, image data cache algorithm using offline cache scheduling and cache memory division, and a parallel operation and pipeline structure considering dependencies in operations and timing requirements. The implemented system is applied to some experiments using Full HD color image inputs, and the results are presented in comparison with the results of PC software to show the validity of the designed system.
디지털 제어기의 부분적 초기값 보상을 통한 천이 응답 특성 향상
도태용(Tae-Yong Doh),류정래(Jung Rae Ryoo) 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.4
In switching from the track-seeking or track-jumping control mode to track-following control mode in hard disk drives or optical disk drives, initial values of the feedback controller are tuned to improve the transient response. In general, all the initial values of the controller have been compensated for this purpose. In this paper, by partially compensating initial values of digital controllers, we achieve a good performance of the transient response. In the proposed method for IVC (Intial Value Compensation), LMIs (Linear Matrix Inequalities) are used, which includes conditions for improving the performance of the transient response such as reducing a tracking error and control efforts. We obtain optimal initial values of the controller by solving an optimization problem with constraints represented by only one LMI. Although initial values of the controller are partially compensated, we can show that not only a sufficient performance of the transient response is obtained but also control efforts are diminished. The feasibility of the method is verified by simulation studies.