• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.8-14
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• 2008

This paper aims at finding out dominant robot configurations with maximal position errors, which can be attributed to the parameter errors, by using Monte-Carlo simulation for error analysis of a 3-axis SCARA(Selective Compliance Assembly Robot Arm) type robot. In particular, the Monte-Carlo simulation is used for virtually measuring on the position errors, instead of physical measurement. In order to measure the observability of the model parameters with respect to a set of robot configurations, we propose the observability index which is defined as the product of singular values for error propagation matrices. Thus the index can be used for discriminating dominant robot configurations from a set of simulated ones in conjunction with standard deviation of positional errors, This paper analyzed error by robot positional error.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.1
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• pp.85-92
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• 2006

A new silicon micro flow sensor with multiple temperature sensing elements was proposed and fabricated in considering wide range flow velocity measuring device. Thermal mass flow sensor measures the asymmetry of temperature profile around the heater which is modulated by the fluid flow. A micro mass flow sensor was normally composed of a central heater and a pair of temperature sensing elements around it. A new 2-D wide range micro flow sensor structure with three pairs of temperature sensing elements and a central heater was proposed and numerically simulated by Finite Difference Formulation to confirm the feasibility of the wide flow range sensor structure. To confirm the simulation result, the new flow sensor was fabricated on silicon substrate and the basic flow sensing properties of the sensor were measured.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.6
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• pp.619-625
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• 1997

In this paper, we show that the rotor position of the bifilar-wound hybrid stepping motors for the closed-loop drives is detected by the phase current measurement. We propose an instantaneous phase current equation, which is the function of electrical angle, by modeling the stepping motor including motor driving circuits. We also analyze the relationship between phase current and rotor position from the computer simulation results. We show that the information about the rotor position is obtained from the phase current amplitude and its derivatives at the instance of ${\pi}/2$ electrical angle of excitation voltage.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.3
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• pp.219-226
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• 1997

지구를 원궤도로 돌고 있는 위성 운동과 지진에 흔들리는 건물 진동을 선형 확률적 미분 방정식으로 나타내고 최적화 제어를 위하여 리스크 센서티브 제어기를 사용한다. 리스크 센서티브 파라미터에 따라서 코스트 함수의 평균과 분산이 변하게 된다. 이 파라미터가 무한히 커지면 리스크 센서티브 제어기는 기존의 LQG 제어기와 같아지므로 리스크 샌서티브 제어이론은 LQG 제어 이론을 포함한 종합적인 이론이다. 이 논문에서는 리스크 센서티브 이론을 소개하고, 리스크 센서티브 제어 방식의 성능 측정및 평가 방법을 도출하기 위하여 공분산을 이용하면 리스크 센서티브 제어기는 기존의 LQG 제어기 보다 우수한 성능을 나타낸다는 것을 보여준다. 시뮬레이션을 통하여 위성의 자세및 궤도 운동 제어와 건물 진동 제어에 활용된 리스크 센서티브 제어기의 향상된 성능과 안정성을 보여준다.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.5
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• pp.499-504
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• 2011

In this paper, we suggest a method for discretized frequency modulations of ultrasonic signals. A continuous sweep of frequency modulation signals can be modelled with fine levels of discretization. If the ultrasound signals are modulated with monotonically decreasing frequencies, then the cross-correlation between an emitted signal and received signal can be used to identify the distance of multiple target objects. For the discretized frequency synthesis, CF ultrasounds with different frequencies are serially ordered. The auto-correlation test with the signal shows effective results for distance estimation. The discretized frequency syntheses have better distance resolution than CF ultrasound signals and the resolution depends on the number of the combined ultrasound frequencies.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.139-147
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• 2009

When the visually impaired walks inside a building like corridor, a GPS cannot be useful for the walker in estimating his or her position unlike the case of outdoor space. This paper presents two novel methods to measure the walking distance using a low cost camera worn on the chest of the visually impaired. In the first method we analyze the periodic variation of image focusing values. Walking steps are counted by checking the period for the rough measure of the walking distance. The second method counts the step number by monitoring fixtures on the ceiling, which have a certain interval. Lamps on the ceiling appeared on the video are monitored in this paper. The T-S fuzzy theory is used to detect lamps, and the walking steps are estimated by the positional variation of the lamp due to the gait of the walker. The two methods are tested in real experiment, and the results are compared.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.9
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• pp.906-908
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• 2009

AVI (Automatic Vision Inspection) systems automatically detect defect features and measure their sizes via camera vision. It is important to predict the performance of an AVI to meet customer's specification in advance. Also the prediction can indicate the level of current performance of an AVI system. In this paper, we propose a statistical method for prediction of false alarm rate regarding inconsistency of defect size measurement process. For this purpose, only simple experiments are needed to measure the defect sizes for certain number of times. The statistical features from the experiment are utilized in the prediction process. Therefore, the proposed method is swift and easy to implement and use. The experiment shows a close prediction compared to manual inspection results.

• ICROS
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• v.22 no.4
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• pp.27-34
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• 2016

몸에 착용할 수 있는 컴퓨터인 웨어러블 디바이스의 기능이 구글 글래스와 애플 워치 이후 빠른 속도로 발전하고 있다. 특히 헬스케어 분야에서 엄청난 속도로 진화하고 있다. 구글은 스마트 워치로 자기장을 주면서 암세포를 손목밴드에서 파괴시킬 수 있는 내용의 특허를 내고, 실용화에 박차를 가하고 있다. 헬스케어 웨어러블 디바이스에서 측정되는 모든 개인 생체정보가 데이터베이스로 연결되고, 이 빅데이터가 건강관리와 예방치료에 활용되면 청춘 100세, 수명 120시대는 달성될 수 있다는 전망이다. 하루가 멀다하고 신제품, 신기술이 발표되고 있는 헬스케어용 웨어러블 디바이스의 최근의 개발 동향 및 응용 현황에 대해 정리하여 보았다.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.3
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• pp.243-251
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• 2014

In inference fit assembly process of the industrial robot, it basically needs the force data. One of the typical methods to get the force data is attaching torque sensors on the robot arm joint or end effector. This is effective way to reduce time delay and to improve preciseness of force control, but this method has several problems. To solve that problem, this paper suggests method which measures assembly force without torque sensor by using the sliding perturbation observer(SPO) and assembly process based on SPO to assemble successfully in inference assembly

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.415-418
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• 2002

MR의 자율주행 기능에는 추종, 접근, 충돌회피, 경고 등의 여러 기능이 있다. 이 기능들을하나의 Neural Network로 학습시키는 것은 어려운 일이다. 이것을 보안하고자 기능들을 각각의 Module로 구성하여 상황에 맞게 학습된 Module의 출력 값으로 MR을 제어하였다 로봇은 인간의 감각을 대신할 수 있는 다중 초음파 센서와 PC 카메라를 장착하고 있으며, 이곳에서 측정된 환경정보 데이터들은 Modular Neural Network을 통해 학습이 이루어진다 MNN에서의 출력값은 Gating Network(GN)에서 로봇의 진행 방향과 속도를 스위칭 출력함으로서 MR을 제어하는데 사용된다. MNN 내 EN의 활성화 함수 최적결합을 통해 효과적인 MNN을 구성하였다. 본 논문에서는 Modular Neural Network의 Expert Network(EN)을 최적설계 하였고, 제안한 MNN의 검증을 위해 실시간으로 MR에 구현하였다.