• 조명전기설비학회논문지
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• 제26권1호
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• pp.29-37
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• 2012

A simple and effective dead time compensation scheme for a PWM inverter-fed permanent magnet synchronous motor (PMSM) drive using the model reference adaptive control (MRAC) and coordinate transformation is presented. The basic concept is to first transform a time-varying disturbance caused by the dead time and inverter nonlinearity into unknown constant or slowly-varying one by the coordinate transformation, and then use the MRAC design technique to estimate this parameter in the stationary reference frame. Since the MRAC scheme is a suitable way of estimating such a parameter, the control performance can be significantly improved as compared with the conventional observer-based method tracking time-varying parameters. In the proposed scheme, the disturbance voltage caused by the dead time is effectively estimated and compensated by on-line basis without any additional circuits nor existing disadvantages as in the conventional methods. The asymptotic stability is proved and the effectiveness of the proposed scheme is verified.

• 한국멀티미디어학회논문지
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• 제10권6호
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• pp.716-725
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• 2007

In this paper we describe a motion tracking algorithm for 3D human animation using stereo vision system. This allows us to extract the motion data of the end effectors of human body by following the movement through segmentation process in HIS or RGB color model, and then blob analysis is used to detect robust shape. When two hands or two foots are crossed at any position and become disjointed, an adaptive algorithm is presented to recognize whether it is left or right one. And the real motion is the 3-D coordinate motion. A mono image data is a data of 2D coordinate. This data doesn't acquire distance from a camera. By stereo vision like human vision, we can acquire a data of 3D motion such as left, right motion from bottom and distance of objects from camera. This requests a depth value including x axis and y axis coordinate in mono image for transforming 3D coordinate. This depth value(z axis) is calculated by disparity of stereo vision by using only end-effectors of images. The position of the inner joints is calculated and 3D character can be visualized using inverse kinematics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1231-1233
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• 1996

This paper presents an estimation of relative distance and angle from a mobile robot to an object. From the number of pulses required to make the mobile robot move to the feature point, we find the relative distance and angle between the mobile robot and the object. The proposed method shows a practical way of measuring the relative distance and angle between the mobile robot and an object without setting up real world coordinate system.

• 제어로봇시스템학회논문지
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• 제15권12호
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• pp.1223-1231
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• 2009

We derive a systematic and iterative calibration algorithm, and position and pose estimation algorithm for the mobile robots in formation system based on the vision system. In addition, we develop a coordinate matching algorithm which calculates matched sequence of order in both extracted image coordinates and object coordinates for non interactive calibration and pose estimation. Based on the results of calibration, we also develop a camera simulator to confirm the results of calibration and compare the results of simulations with those of experiments in position and pose estimation.

• Journal of Information Processing Systems
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• 제18권3호
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• pp.293-301
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• 2022

Direction of arrival (DOA) estimation of space signals is a basic problem in array signal processing. DOA estimation based on the multiple signal classification (MUSIC) algorithm can theoretically overcome the Rayleigh limit and achieve super resolution. However, owing to its inadequate real-time performance and accuracy in practical engineering applications, its applications are limited. To address this problem, in this study, a DOA estimation algorithm with high parallelism and precision based on an analysis of the characteristics of complex matrix eigenvalue decomposition and the coordinate rotation digital computer (CORDIC) algorithm is proposed. For parallel and single precision, floating-point numbers are used to construct an orthogonal identity matrix. Thus, the efficiency and accuracy of the algorithm are guaranteed. Furthermore, the accuracy and computation of the fixed-point algorithm, double-precision floating-point algorithm, and proposed algorithm are compared. Without increasing complexity, the proposed algorithm can achieve remarkably higher accuracy and efficiency than the fixed-point algorithm and double-precision floating-point calculations, respectively.

• 전력전자학회논문지
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• 제12권1호
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• pp.65-73
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• 2007

본 논문은 1-Hz의 낮은 고정자 전류 주파수에서도 동작하는 순수적분 기반의 자속추정을 위한 온라인 전류측정 오차 보상방법을 제안한다. 오프셋 전류와 변환이득오차에 의한 역상분 전류 성분은 상태관측기를 이용하여 제거하고, 동시에 변환이득오차에 의한 역상분 전류는 동기좌표계에서 영구자석에 의하여 발생된 q축 자속을 기준모델에 의한 값과 추정된 자속에 의한 값 사이의 차이에 의하여 보상한다. 이 보상기는 PI제어기를 이용하여 두 값 사이의 오차가 0이 되도록 제어한다. 또한 적분기 초기값 오차 및 관측기의 전동기 상수 오차에 의한 잔여오차 보상방법도 제안하였다. 타당성을 입증하기 위하여 1.1-kW 영구자석형 동기전동기(PMSM)에 제안된 보상 방법을 구현하여 다양한 실험을 수행하였다.

• 한국ITS학회 논문지
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• 제21권3호
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• pp.83-95
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• 2022

본 논문은 자율주행 차량 적용을 위한 객체 검출과 거리 추정을 수행하는 시스템을 제안한다. 객체 검출은 최근 활발하게 사용되는 딥러닝 모델 YOLOv4의 특성을 이용해서 입력 이미지 비율에 맞춰 분할 grid를 조정하고 자체 데이터셋으로 전이학습된 네트워크로 수행한다. 검출된 객체까지의 거리는 bounding box와 homography를 이용해 추정한다. 실험 결과 제안하는 방법에서 전반적인 검출 성능 향상과 실시간에 가까운 처리 속도를 보였다. 기존 YOLOv4 대비 전체 mAP는 4.03% 증가했다. 도심로 주행시 빈출하는 보행자, 차량 및 공사장 고깔(cone), PE드럼(drum) 등의 객체 인식 정확도가 향상되었다. 처리 속도는 약 55 FPS이다. 거리 추정 오차는 X 좌표 평균 약 5.25m, Y 좌표 평균 0.97m으로 나타났다.

• 제어로봇시스템학회논문지
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• 제15권4호
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• pp.379-384
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• 2009

A human gaze detection and tracing method is importantly required for HMI(Human-Machine-Interface) like a Human-Serving robot. This paper proposed a novel three-dimension (3D) human gaze estimation method by using a face recognition, an orientation estimation and SVMs (Support Vector Machines). 2,400 images with the pan orientation range of $-90^{\circ}{\sim}90^{\circ}$ and tilt range of $-40^{\circ}{\sim}70^{\circ}$ with intervals unit of $10^{\circ}$ were used. A stereo camera was used to obtain the global coordinate of the center point between eyes and Gabor filter banks of horizontal and vertical orientation with 4 scales were used to extract the facial features. The experiment result shows that the error rate of proposed method is much improved than Liddell's.

• 제어로봇시스템학회논문지
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• 제12궈1호
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• pp.9-14
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• 2006

This paper presents methods of robot localization using recent radio frequency identification technology. If the absolute position and orientation of a tag are given in an indoor environment where RFID tags are installed, a robot can estimate its location using the relationship of the identified tag and the robot in a relative coordinate. To derive this relationship, we propose three estimation techniques using a model of a RFID reader, the direction of identification and the detection range. In this algorithm, a suitable estimation method is selected out of the three proposed techniques depending on the situations and trajectory of robot in the detection range. Simulation and experimental results show that the proposed methods can provide good performance for localization.

• 한국소음진동공학회논문집
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• 제23권11호
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• pp.966-972
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• 2013

Measurement or estimation of tilt angle is necessary for balancing robot such as Segway which is considered as a next generation transportation vehicle. However, it requires high-cost accurate sensors to hold balancing during stationary and moving situations. In this paper, a tilt angle estimation of a plane rotating in a vertical plane using low-cost sensors. Estimation using a set of 2-axis orthogonal accelerometers along with an inaccurate rate gyro has been considered. Feasibility and performance of the proposed technique has been verified through some experimental results.