태양추적장치를 위한 태양위치계산에서의 제언

박영칠(Park Young Chil) 한국태양에너지학회 2016 한국태양에너지학회 논문집 Vol.36 No.6

As the usage of sun tracking system in solar energy utilization facility increases, requirement of more accurate computation of sun position has also been increased. Accordingly, various algorithms to compute the sun position have been proposed in the literature and some of them insist that their algorithms guarantee less than 0.01 degree computational error. However, mostly, the true meaning of accuracy argued in their publication is not clearly explained. In addition to that, they do not clearly state under what condition the accuracy they proposed can be guaranteed. Such ambiguity may induce misunderstanding on the accuracy of the computed sun position and ultimately may make misguided notion on the actual sun tracking system’s sun tracking accuracy. This work presents some comments related to the implementation of sun position computational algorithm for the sun tracking system. We first introduce the algorithms proposed in the literature. And then, from sun tracking system user’s point of view, we explain the true meaning of accuracy of computed sun position. We also discuss how to select the proper algorithm for the actual implementation. We finally discuss how the input factors used in computation of sun position, like time, position etc, affect the computed sun position accuracy.

Trajectory-based vehicle tracking at low frame rates

Lee, Giyoung,Mallipeddi, Rammohan,Lee, Minho Elsevier 2017 expert systems with applications Vol.80 No.-

<P><B>Abstract</B></P> <P>In smart cities, an intelligent traffic surveillance system plays a crucial role in reducing traffic jams and air pollution, thus improving the quality of life. An intelligent traffic surveillance should be able to detect and track multiple vehicles in real-time using only limited resources. Conventional tracking methods usually run at a high video-sampling rate, assuming that the same vehicles in successive frames are similar and move only slightly. However, in cost effective embedded surveillance systems (e.g., a distributed wireless network of smart cameras), video frame rates are typically low because of limited system resources. Therefore, conventional tracking methods perform poorly in embedded surveillance systems because of discontinuity of the moving vehicles in the captured recordings. In this study, we present a fast and light algorithm that is suitable for an embedded real-time visual surveillance system to detect effectively and track multiple moving vehicles whose appearance and/or position changes abruptly at a low frame rate. For effective tracking at low frame rates, we propose a new matching criterion based on greedy data association using appearance and position similarities between detections and trackers. To manage abrupt appearance changes, manifold learning is used to calculate appearance similarity. To manage abrupt changes in motion, the next probable centroid area of the tracker is predicted using trajectory information. The position similarity is then calculated based on the predicted next position and progress direction of the tracker. The proposed method demonstrates efficient tracking performance during rapid feature changes and is tested on an embedded platform (ARM with DSP-based system).</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new vehicle tracking method is proposed for an embedded traffic surveillance system. </LI> <LI> The proposed method demonstrates efficient tracking performance at a low frame rate. </LI> <LI> The proposed method employs greedy data association based on appearance and position similarities. </LI> <LI> To manage abrupt appearance changes, manifold learning is used. </LI> <LI> To manage abrupt motion changes, trajectory information is used to predict the next probable position. </LI> </UL> </P>

IMU based Walking Position Tracking using Kinematic Model of Lower Body and Walking Cycle Analysis

송기욱(Kee Wook Song),송영은(Young Eun Song),정회룡(Hoeryong Jung) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.10

This paper proposes a walking position tracking method using inertial measurement unit (IMU) based on kinematic model of human body and walking cycle analysis. A kinematic model of lower body consisting of 9 coordinate frames and 7 links is used to estimate walking trajectory of the body based on rotation angles of the lower body measured by IMU. In this method, the position of left or right end frame of the lower body which is in contact with the ground is first identified and set as the reference position. The position of the base frame attached on the center of pelvis is then computed using the kinematic model and the reference position. One can switch the reference position with the position of the other end frame at the moment of heel strike. The proposed position tracking method was experimentally validated. Experimental result showed that position tracking errors were within 1.4% of walking distance for straight walking and 2.2% for circular walking.

구형의 섬광체를 이용한 방사선 스펙트로스코피 검출기 설계 및 방사선원 위치 추적 시스템 개발

이승재(Seung-Jae Lee) 한국방사선학회 2020 한국방사선학회 논문지 Vol.14 No.6

구(sphere)형의 섬광체를 사용한 방사선 스펙트로스코피 검출기를 설계하였고, 여러 대의 검출기를 사용하여 방사선원의 위치를 추적하는 시스템을 개발하였다. 방사선원의 위치 추적은 방사선의 수는 거리의 역자승 법칙에 따라 감소하는 이론을 바탕으로 위치 추적 알고리듬을 설계하였으며, 여러 위치의 방사선원에서 발생된 방사선의 수를 측정하여 알고리듬을 통해 위치를 계산하였다. 방사선원에서 발생되는 방사선은 각 검출기에서 서로 다른 계수로 검출되며, 이러한 검출되는 계수의 차이는 거리의 역자승에 비례하여 달라진다. 설계한 방사선원 위치 추적 시스템의 성능을 검증 및 평가하기 위해 Geant4 Application for Tomographic Emission (GATE) 시뮬레이션을 실시하였으며, 서로 다른 위치에 놓이 방사선원에서 발생된 방사선을 각 검출기로 계수하였다. 측정된 방사선의 수는 방사선원 위치 추적 알고리듬을 통해 위치가 추적되었으며, 실제 방사선원의 위치와 알고리듬으로 계산된 위치와의 오차를 평가하였다. 실제 방사선원의 위치와 계산된 위치와의 오차는 평균 X축 0.11%, Y축 0.37%로 측정되었으며, 매우 정확하게 위치를 측정할 수 있음이 검증되었다. A radiation spectroscopy detector using a spherical scintillator was designed, and a system was developed to track the position of a radiation source using several detectors. The position tracking algorithm was designed based on the theory that the number of radiations decreases according to the inverse square law of distance, and the position of the radiation source was calculated by measuring the number of radiations generated from the radiation sources at various positions. The radiation generated from the radiation source is detected by different coefficients in each detector, and the difference between these detected coefficients varies in proportion to the inverse square of the distance. Geant4 Application for Tomographic Emission (GATE) simulation was performed to verify and evaluate the performance of the designed radiation source position tracking system, and radiation generated from radiation sources placed at different positions was counted with each detector. The number of measured radiations was tracked through the radiation source position tracking algorithm, and the error between the actual radiation source position and the position calculated by the algorithm was evaluated. The error between the position of the actual radiation source and the calculated position was measured as an average of 0.11% on the X-axis and 0.37% on the Y-axis, and it was verified that the position can be measured very accurately.

광학식 무선 위치 추적 장치의 개발과 성능 검증

백준민(Junmin Baek),노건우(Gunwoo Noh),서준호(Joonho Seo) 제어로봇시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.12

Position-tracking devices have been used in various fields, including medical surgery and augmented reality. In this paper, a wireless optical position-tracking module with a processor that can perform self-3D tracking is developed, and the position coordinates of the cube marker are obtained using a position-tracking algorithm. Software is developed to send position coordinate data to the host computer using a wireless UDP network and make it visible at the host computer. To verify the networking system speed and evaluate the accuracy of the position coordinate data, we conducted experiments using the host computer and a two-axis electronic stage. The results demonstrate a speed of 26.81 ㎳ on average with a frequency of 37.3 ㎐. The difference between the moving distance of the actual cube marker and measuring cube marker is 0.764 ㎜ on average, with an RMSE of 0.973 ㎜. This system enables the installation of the device in any space and permits the use of a wireless network, eliminating the data transmission line and simplifying the configuration. Furthermore, many optical position-tracking modules can be installed to solve the problem where the obstacle blocks the cube marker.

Radiation source position tracking system using multiple radiation spectroscopy detectors

Lee Seung-Jae,Baek Cheol-Ha 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.1

Gamma cameras are often used to detect and locate radiation sources. A gamma camera can acquire a 2D image to track the planar position. The use of a pinhole collimator or diverging collimators is essential to monitoring over a wide range; however, the sensitivity is very low and it takes a long time to track the position. To solve this problem, a system for tracking 2D positions using radiation spectroscopy detectors has been developed. Acquisition of planar images using the location measurement algorithm with radiation measured by spectroscopy detectors results in a significant improvement in sensitivity compared with a system using a gamma camera because a collimator is not used. However, if the radiation source is located at different heights on the same 2D plane, there is a limit to tracking the exact position, even with the positioning algorithm. To solve this problem, we designed a system to measure the 3D position using five radiation spectroscopy detectors. The principle of the system was the number of incident radiations to the same area was differently depending on the square of the distance, and the performance of the system designed was evaluated using Geant4 Application for Tomographic Emission (GATE). The average error was 2.03 ± 2.39%, 2.20 ± 2.92%, and 4.78 ± 4.52% for the X, Y, and Z positions, respectively.

일사량 변화에 따른 전력손실을 고려한 새로운 태양광 추적 시스템 제어

박기태(Ki-Tae Park),최정식(Jung-Sik Choi),정동화(Dong-Hwa Chung) 한국조명·전기설비학회 2008 조명·전기설비학회논문지 Vol.22 No.6

본 논문은 태양광 발전 추적 시스템의 발전량을 증가시키기 위해 일사량 급변에 대한 추적 장치 기동 시 전력소모를 고려한 새로운 추적 알고리즘을 제시한다. 종래의 태양광 발전에 사용되는 센서방식의 추적시스템은 구름 및 안개 등 급변하는 기후환경에 의해 추적 장치의 오동작의 문제점으로 태양의 정확한 추적이 불가능하다. 또한 프로그램 방식의 경우에는 기후 환경의 외부 요인에 대응하지 못함으로서 추적 장치의 불필요한 동작으로 인한 에너지 소비가 발생된다. 이러한 이유로 태양 추적 장치가 실시간으로 태양의 방위각 및 고도 각을 추정하는 경우에도 실제 태양광 발전량은 특정한 위치에 고정되어 있는 경우보다 발전량이 증가하지 못한다. 본 논문에서는 이러한 전력 소모를 줄이기 위한 추적시스템의 새로운 제어 알고리즘을 제시한다. 또한 종래의 태양광 추적 방식과 제시한 방법의 효율을 분석하고, 실증연구를 통하여 제시한 알고리즘의 타당성을 입증한다. In this paper proposes a novel tracking algorithm regarding the power loss when operating a tracking system for a rapidly changing insolation to improve the power of PV tracking system. The tracking system of sensor method used in a conventional PV power station is unable to exactly track a sun position when lacking in the intensity of radiation and has the problem is malfunction of tracking system by a rapidly changing climatic. The tracking system of program method spends too much energy on the unnecessary operation of tracking system because that is unable to adapt itself to a outside factor of climatic environment. In case of tracking an azimuth and altitude of the sun in realtime, therefore, the actual PV power is less increasing than the power of tracking system fixed a specific position. To reduce the power loss, this paper proposes a novel control algorithm of the tracking system. Also, this paper is analyzed efficiency of traditional solar tracking method and proposed method, prove validity of proposed algorithm through demonstrable study.

Human Body Position Estimation System using Electric Field Resonance Coupling

Shimon Ajisaka,Sousuke Nakamura,Kiyoaki Takiguchi,Akira Hirose,Hideki Hashimoto 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

Today in terms of security and caring, more various and robust information system about human existence in indoor environment (ex. rooms, buildings) are needed. Especially, human position estimation system in such kinds of spaces is basic. Generally, such kind of systems use radiowave devices, cameras and ultrasonic devices to estimate human position. But these kind of systems have some weakpoint when the system tries to estimate position. A purpose of this paper is to propose novel human position estimating system using electric field resonance coupling and validate the evidence for possibility of human position sensing system using resonance coupling by simulation experiment. In simulation experiment results using Gabriel"s human phantom, relation between electric field strength and distance between sensor and human are confirmed. In conclusion, feasibility of the proposed human position estimation system is shown.

Integrative Tracking Control Strategy for Robotic Excavation

Niraj Reginald,Jaho Seo,Moohyun Cha 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.10

Automated excavation is hard to achieve due to several inherent problems such as resistive force acting against the bucket, non-homogenous dynamics of various excavation media, and nonlinearities of the excavator’s hydraulics system. To deal with this issue, this paper provides an integrative control strategy for successful autonomous excavation that considers the mutually associated factors, i.e., position, contour, and force control. For the position tracking, a non-linear PI controller was designed to track the position of individual actuators of the excavator and thereby control the bucket tip’s position. In addition, the contour control technique was applied to achieve an optimal excavation path to minimize contour errors. Finally, to compensate for the ground resistive force during digging tasks, a force impedance controller was designed along with the time-delayed control that reducesthe effect of dynamic uncertainties. Experimental results with a modified mini-wheeled excavator show that the developed integrative tracking control strategy can provide a comprehensive solution to improving the tracking performance for autonomous excavation that can simultaneously deal with the critical components of position, contour, and force control.

LabVIEW를 활용한 고정밀도 태양추적장치 개발

오승진(Oh Seung Jin),조일식(Cho Yil-Sik),이윤준(Lee Yoon Joon),천원기(Chun Wongee) 한국태양에너지학회 2009 한국태양에너지학회 학술대회논문집 Vol.- No.-

There have been many solar tracking systems developed for the high accuracy in solar tracking. One of the key components of any motion control system is software. LabVIEW offers an ideal combination of flexibility ,ease-of-use and well-integration with other I/O pieces for developing solar tracking system. Real-time solar positions which vary with GPS’s data are used simultaneously to control the solar tracker by a chain of operating modes between the open and closed loops. This paper introduces a step by step procedure for the fabrication and performance assessment of a precision solar tracking system. The system developed in this study consists of motion controllers, motor drives, step-motors, feedback devices and application. CRD sensors are applied for the solar tracking system which play a primary role in poor conditions for tracking due to a gear backlash and a strong wind. Mini-dish was used as a concentrator for collecting sun light. The solar position data , in terms of azimuth and elevation, sunrise and sunset times was compared with those of KASI(Korea Astronomy & Space Science Institute). The results presented in this paper demonstrate the accuracy of the present system in solar tracking and utilization.