• 대한임베디드공학회논문지
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• 제9권4호
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• pp.237-243
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• 2014

In this paper we present an real-time obstacle avoidance technique of autonomous mobile robot with steering system and implementation of user interface for mobile devices with Android platform. The direction of autonomous robot is determined by virtual force field concept, which is based on the distance information acquired from 5 ultrasonic sensors. It is converted to virtual repulsive force around the autonomous robot which is inversely proportional to the distance. The steering system with PD(proportional and derivative) controller moves the mobile robot to the determined target direction. We also use PSD(position sensitive detector) sensors to supplement ultrasonic sensors around dead angle area. The mobile robot communicates with Android mobile device and PC via Ethernet. The video information from CMOS camera mounted on the mobile robot is transmitted to Android mobile device and PC. And the user can control the mobile robot manually by transmitting commands on the user interface to it via Ethernet.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.1984-1986
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• 2001

In order to provided continuous solutions, latest developing navigation systems tend to integrate GPS receiver with INS or DR. Using the GPS carrier-phase measurements, an attitude GPS receiver with three antennas obtain the 3-dimensional attitude such as roll, pitch, and heading as well as position and velocity. With these angle measurements, in the attitude GPS/INS integrated system, attitude or gyro errors can be directly compensated. In this paper, we develop an integrated navigation system that combines attitude GPS receiver with INS. The performance of real-time integrated navigation system is determined by not only the implements of integration filter but also the synchronization of measurements. To meet these real-time requirements, the navigation software is implemented in multi-tasking structure in this paper. We also employ time-synchronization technique in the multi-sensor fusion. Experimental results show that the performance of the attitude GPS/INS integrated system is consistent even when cycle-slip occurs in carrier-phase measurements.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.299-301
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• 1996

Recently, as a result of the progress in power electronics and magnet technology, the applications of inverter fed BLDC Motor have increased for industry and home appliance. Also because of the high efficiency, good acoustic noise characteristic, BLDC Motor applications are growing. However, BLDC Motor requires position sensor, which has many problems such as high cost, more space and difficult to install. Therefore, sensorless control algorithm is being studied. In this paper, sensorless algorithm for interior permanent magnet BLOC motor adaptable for home appliance is proposed. The maximum torque per amp operation with advance angle considering load torque and speed was simulated and verified through the experiment.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제7권4호
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• pp.228-235
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• 2007

The main purpose of this paper is to manage the container property effectively at the container yard by applying the RTLS technology to the field of port logistics. Yet, many kinds of noises happen to be inputted with the distance value(between the reader and the tag) which is to be inputted into the location identification algorithm, which makes the distance value jumped due to the system noise of the ultrasonic sensor module and the measurement noise. The Kalman Filter is widely used to prevent this jump occurrence; the noises are eliminated by using the EKF(Extended Kalman Filter) while considering that the distance information of the ultrasonic sensor is non-linear. Also, the 3D RTLS system at the port container yard suggested in this research is designed not to be interrupted for its ultrasonic transmission by positioning the antenna at the front of each sector of the container where the active tags are installed. We positioned the readers, which function as antennas for location identification, to four places randomly in the absolute coordinate and let the positions of the active tags identified by using the distance data delivered from the active tags. For the location identification algorithm used in this paper, the triangulation measurement that is most used in general is applied and newly reorganized to calculate the position of the container. In the first experiment, we dealt with the error resulting in the angle and the distance of the ultrasonic sensor module, which is the most important in the hardware performance; in the second, we evaluated the performance of the location identification algorithm, which is the most important in the software performance, and tested the noise cancellation effects for the EKF. According to the experiment result, the ultrasonic sensor showed an average of 3 to 5cm error up to $45^{\circ}$ in case of $60^{\circ}$ or more, non-reliable linear distances were obtained. In addition, the evaluation of the algorithm performance showed an average of $4^{\circ}{\sim}5^{\circ}$ error due to the error of the linear distance-this error is negligible for most container location identifications. Lastly, the experiment results of noise cancellation and jump preservation by using the EKF showed that noises were removed in the distance information which was entered from the input of the ultrasonic sensor and as a result, only signal was extracted; thus, jumps were able to be removed and the exact distance information between the ultrasonic sensors could be obtained.

• 한국정보통신학회논문지
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• 제17권11호
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• pp.2541-2546
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• 2013

본 논문에서는 가시선 데이터링크용 추적안테나 시스템에 적용하기 위한 방위각 보정 알고리즘에 대해 연구한다. 이동하는 물체와 가시선 통신링크를 유지하기 위해서는 추적안테나 시스템이 필수적이다. 방위각과 고각계산을 위해서는 이동체와 안테나시스템의 GPS값을 이용하는데, 이때 두 좌표계의 동일성을 유지하기 위해서 초기에 지자기센서나 beacon등을 이용하여 보정을 하게 된다. 하지만 지형적으로 지자기교란이 생기기 쉬운 장소에서는 정확한 보정이 어렵다. 따라서 본 논문에서는 초기에 RF신호의 수신세기추적을 통해서 신호의 발생 위치를 검출하고 검출된 위치까지의 방위각 보정 값을 계산하여 통신링크개설 후 수신된 GPS값에 보정 값을 적용함으로서 주변의 영향을 최소화하면서 쉽고 빠르게 보정할 수 있다.

• 한국자동차공학회논문집
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• 제19권6호
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• pp.68-75
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• 2011

A vehicle fuel economy is very important issue in view of fuel cost and environmental regulation. It has been improved according to the performance improvement of the vehicle engine, power train and many components. It was evaluated at given mode (LA-4, FTP-75, etc) on an engine dynamometer or computer simulation program. In this paper, the fuel economy improvement cruise control algorithms as controling a vehicle velocity by road load calculated and predicted in a real expressway with gradient was studied. Firstly, the altitude and distance data which was measured with GPS sensor was already installed in the ECU of a vehicle. Then the vehicle equipped with GPS receiver is driven the same expressway. The ECU calculates the gradient angle and the in-/decreasing velocity using the gradient angle by comparing the current received distance and altitude data from GPS with the saved data ahead of the vehicle. Therefore the ECU can calculate and predict the vehicle velocity considering tolerance velocity of next position with running. Then the ECU controls the vehicle velocity to meet this predicted velocity in all section. Three cruise control algorithms with the different velocity profiles for the improvement of fuel economy are proposed and compared with the computer simulation results that the vehicle runs on Youngdong expressway. The proposed CVELCONT2 and CVELCONT3 algorithms were improved 3.7% and 4.8% of fuel economy compared with CONSTVEL which is steady cruising algorithm. These two algorithms are recommended as the Eco-cruise drive methodologies in this paper.

• 한국군사과학기술학회지
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• 제15권6호
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• pp.721-728
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• 2012

The tracked SUGVs(Small Unmanned Ground Vehicles) are frequently operated in the narrow slope such as stairs and trails. But due to the nature of the tracked vehicle which is steered using friction between the track and the ground and the limited field of view of driving cameras mounted on the lower position, it is not easy for SUGVs to trace narrow slopes. To properly trace inclined narrows, it is very important for SUGVs to keep it's heading direction to the slope. As a matter of factor, no roll value control of a SUGV can makes it's heading being located in the direction of the slope in general terrains. But, the problem is that we cannot directly control roll motion for SUGV. Instead we can control yaw motion. In this paper, a new slope driving method that enables the vehicle trace the narrow slopes with IMU sensor usually mounted in the SUGV is suggested which including an estimation technique of the desired yaw angle corresponding to zero roll angle. In addition, a fuzzy steering controller robust to changes in driving speed and the stair geometry is designed to simulate narrow slope driving with the suggested method. It is shown that the suggested method is quite effective through the simulation.

• 한국전자통신학회논문지
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• 제14권5호
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• pp.1009-1018
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• 2019

본 연구에서는 표면근전도 측정기 기반의 재활의료기기의 설계 및 구현에 관한 내용을 기술한다. 재활시스템은 BLDC모터와 모터 드라이브를 이용하여 제어된다. BLDC모터 드라이브는 동작제어를 하며, 속도는 외부 서보모터를 통해 드라이브를 제어한다. 또한 모터 외부에 결합된 포텐쇼미터는 모터에 의해 회전하는 부하 위치 정보를 전달한다. 재활 알고리즘은 환자가 일정 각도 범위에서 주기적인 수축 이완 재활운동을 속도단계별로 실행하며 재활운동 시 사용자 설정 단계에 따른 모터를 활용하여 $0{\sim}120[^{\circ}]$의 최대각도로 제한하여 제어한다. 보행 알고리즘은 양쪽 안쪽넓은근에 부착된 표면근전도 측정기로 획득한 신호의 차이 값을 이용하여 근전도 신호가 낮은 다리에 모터제어로 보상해주며 보행운동 시 모터와 표면근전도 측정기를 활용하여 $0{\sim}88[^{\circ}]$의 최대각도로 제한하여 제어한다.

• 지구물리
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• 제9권4호
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• pp.361-369
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• 2006

본 연구에서는 AHRS IMU 센서를 이용하여 동적 위치 결정을 위해 초기화 시험을 실시하여 회귀분석을 통해 시간에 대한 이동체의 자세 보정각에 대해 유도하였으며, 동체 방향(Heading)각의 경우 60sec를 지난 후 1°이내의 변동률로 안정되는 것을 알 수 있었다. 이를 바탕으로 개할지와 준개할지로 구분하여 각 시스템 단독으로 동적 위치결정을 실험한 결과 개할지의 DGPS 단독 시스템인 경우 정확도 면에서는 우수하였지만 데이터 취득이 미비하여 이동간 거리가 12m 내외임을 알 수 있었으며, DGPS/IMU 결합 시스템의 경우 정확도와 데이터 취득 및 이동간 거리가 0.3m 내외임을 알 수 있었다. 준개할지에서 DGPS 단독 시스템의 경우 데이터 취득이 불가능한 곳을 제외하고 평균과 표준 오차를 구한 결과 DGPS〈 FIMU〈 DGPS/IMU 순으로 정확도가 우수한 것을 알 수 있었으며 이동간 거리는 개할지와 마찬가지였다. 그리고 DGPS의 경우 데이터 취득이 불가능한 곳을 여러 구간으로 비교하였을 때 DGPS 단독 시스템의 경우 최대 41.5m 가량 궤적에서 벗어나지만 결합 시스템의 경우 최대 2.2m 이내에 궤적을 구할 수 있었으며, 평균과 표준 오차를 크게 향상시킬 수 있었다. 이러한 항법 시스템을 결합하여 측량분야에 응용해 수치도화 작업내규의 지도에서 위치오차 0.2mm 오차와 비교하였을 때 축척 1 : 1,000 수치지도 작업까지도 가능한 것을 알 수 있었다.

• Advances in aircraft and spacecraft science
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• 제3권4호
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• pp.427-445
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• 2016

Star sensors are the attitude estimation sensors of the satellite orbiting in its path. It gives information to the control station on the earth about where the satellite is heading towards. It captures the images of a predetermined reference star. By comparing this image with that of the one captured from the earth, exact position of the satellite is determined. In the process of imaging, stray lights are eliminated from reaching the optic lens by the mechanical enclosures of the star sensors called Baffles. Research in space domain in the last few years is mainly focused on increased payload capacity and reduction in launch cost. In this paper, a star sensor baffle made of Aluminium is considered for the study. In order to minimize the component weight, material wastage and to improve the structural performance, an alternate material to Aluminium is investigated. Carbon Fiber Reinforced Polymer is found to be a better substitute in this regard. Design optimisation studies are carried out by adopting suitable design modifications like implementing an additional L-shaped flange, Upward flange projections, downward flange projections etc. A better configuration of the baffle, satisfying the design requirements and achieving manufacturing feasibility is attained. Geometrical modeling of the baffle is done by using UNIGRAPHICS-Nx7.5(R). Structural behavior of the baffle is analysed by FE analysis such as normal mode analysis, linear static analysis, and linear buckling analysis using MSC/PATRAN(R), MSC-NASTRAN(R) as the solver to validate the stiffness, strength and stability requirements respectively. Effect of the layup sequence and the fiber orientation angle of the composite layup on the stiffness are also studied.