• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권6호
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• pp.2689-2708
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• 2016

Multi-camera systems which integrate two or more low-cost digital cameras are adopted to reach higher ground coverage and improve the base-height ratio in low altitude remote sensing. To guarantee accurate multi-camera integration, the geometric relationship among cameras must be determined through platform calibration techniques. This paper proposed a combined two-step platform calibration method. In the first step, the static platform calibration was conducted based on the stable relative orientation constraint and convergent conditions among cameras in static environments. In the second step, a dynamic platform self-calibration approach was proposed based on not only tie points but also straight lines in order to correct the small change of the relative relationship among cameras during dynamic flight. Experiments based on the proposed two-step platform calibration method were carried out with terrestrial and aerial images from a multi-camera system combined with four consumer-grade digital cameras onboard an unmanned aerial vehicle. The experimental results have shown that the proposed platform calibration approach is able to compensate the varied relative relationship during flight, acquiring the mosaicing accuracy of virtual images smaller than 0.5pixel. The proposed approach can be extended for calibrating other low-cost multi-camera system without rigorously mechanical structure.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.969-972
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• 2004

This paper describes the mechanism of parallel micro machine platform and its feedback control system for acquiring high accuracy. The parallel micro machine platform that has developed has 5x5x5 work-space and sub-micron accuracy. For the high accuracy, the feedback control system is important but errors in machining and assembling are inevitable. Kinematic calibration is important for this reason. In this paper, various error components are introduced and the effects of error component are analyzed.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.1886-1893
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• 2003

This paper examines the parameter observability of a calibration system that consrains a mobile platform to a planar table to take the calibration data. To improve the parameter observability, we find the optimal configurations providing the calibration with maximum contribution. The QR-decomposition is used to compute the optimal configurations that maximize the linear independence of rows of an observation matrix. The calibration system is applied to the parallel type manipulator constructed for a machining center. The calibration results show that all the necessary kinematic parameters assigned in a Stewart-Gough platform are identifiable and convergent to desirable accuracy.

• 농촌계획
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• 제21권4호
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• pp.177-186
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• 2015

The main objective of this study was to assess the applicability of IoT (Internet of Things)-based flood management under climate change by developing intelligent water level monitoring platform based on IoT. In this study, Arduino Uno was selected as the development board, which is an open-source electronic platform. Arduino Uno was designed to connect the ultrasonic sensor, temperature sensor, and data logger shield for implementing IoT. Arduino IDE (Integrated Development Environment) was selected as the Arduino software and used to develop the intelligent algorithm to measure and calibrate the real-time water level automatically. The intelligent water level monitoring platform consists of water level measurement, temperature calibration, data calibration, stage-discharge relationship, and data logger algorithms. Water level measurement and temperature calibration algorithm corrected the bias inherent in the ultrasonic sensor. Data calibration algorithm analyzed and corrected the outliers during the measurement process. The verification of the intelligent water level measurement algorithm was performed by comparing water levels using the tape and ultrasonic sensor, which was generated by measuring water levels at regular intervals up to the maximum level. The statistics of the slope of the regression line and $R^2$ were 1.00 and 0.99, respectively which were considered acceptable. The error was 0.0575 cm. The verification of data calibration algorithm was performed by analyzing water levels containing all error codes in a time series graph. The intelligent platform developed in this study may contribute to the public IoT service, which is applicable to intelligent flood management under climate change.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2013년도 추계학술발표대회
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• pp.1457-1460
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• 2013

We propose a flexible camera calibration system for mobile platform to calibrate the camera's intrinsic parameters which based on the geometrical property of the vanishing points determined by two perpendicular groups of parallel lines. The system only requires the camera to observe a rectangle card show at a few(at least four)different orientation. The experimental results of the real images show the proposed calibration system in this paper is easy to use and robust.

• 대한전자공학회논문지TC
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• 제37권8호
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• pp.11-23
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• 2000

헤드-아이 보정은 로봇과 같이 이동 가능한 플랫폼상에 장착된 카메라의 방향과 위치를 추정하는 과정이다. 본 논문에서는 다소 제한적인 이동 자유도를 가진 플랫폼에 대해 적용할 수 있는 새로운 헤드-아이 보정 기법을 제시한다. 제안된 보정 기법은 특히 회전 자유도가 없는 선형 플랫폼 위에 장착된 카메라의 상대적인 회전 방향을 구하는데 적용될 수 있다. 서로 다른 두 개의 축 상에서의 순수한 천이(translation) 이동에 의해 얻어진 보정 데이터를 이용하여 회전 방향을 구하는 본 알고리듬은 교정된 스테레오 영상은 epipolar 조건을 만족시켜야 한다는 성질을 이용하여 유도되었다. 본 논문에서는 플랫폼 좌표계상에서의 카메라의 회전 및 천이 파라미터를 구하는 알고리듬을 제시하고, 모의 및 실제 실험 결과를 통해 본 알고리듬의 유효성을 검증한다.

• 한국전자통신학회논문지
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• 제14권1호
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• pp.69-80
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• 2019

본 논문은 PnP(plug and play) 기술을 지원하는 멀티모달 센서 플랫폼을 제안하였다. PnP 기술은 센서 모듈이 연결이 되면 자동으로 인식하여 응용프로그램을 사용하여 손쉬운 센서 제어를 제공한다. 멀티모달 플랫폼을 검증하기 위해, 펌웨어를 사용하여 센서를 실험하였다. 센서 모듈이 연결되면 펌웨어는 센서 모듈을 인지하여 센서 데이터를 읽는다. 따라서, PnP 기술 지원을 통해 소프트웨어 설정 없이 자동으로 센서를 연동할 수 있게 된다. 측정한 센서 데이터는 다양한 왜곡에 의해 오류를 가지고 있다. 따라서, 본 논문은 다항식 계산을 통해 센서의 오류를 보상하고자 한다. 다항식 보상기의 계수를 찾기 위해 유전자 알고리즘 방식을 사용하였다. 실험결과 악조건에서 97%의 오류를 제거하였다. 또한, 제안하는 플랫폼은 다양한 프로토콜의 센서를 지원하기 위해 UART, I2S, I2C, SPI, GPIO를 지원한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.825-830
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• 2004

Kinematic calibration of Gough-Stewart platform using a new measurement device is presented in this paper. The device simultaneously measures components of position and orientation using commercially available gadgets. Additional kinematic parameters are defined to model the sources of inaccuracies for the proposed measurement device. Computer simulations reveal that all kinematic parameters of the Gough-Stewart platform and the additional kinematic parameters of the measurement device can be identified with the partial pose measurements of the device. Results also show that identification is robust for the initial errors and the noise in measurements. The device also facilitates the automation of easurement procedure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.535-540
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• 2000

This paper presents the development of a Parallel-Typed CNC Machining Tool. It is specially designed to machine a complex shaped workpiece by controlling the orientation of the tool. The inverse/direct kinematics of a parallel mechanism is derived and implemented in a PC based controller. With graphics icons, the GUI (Graphic User Interface) program is developed for the CNC programing. The calibration is accomplished by geometric constraint motion, which is a parallel motion of the platform with respect to a table. The calibration result is introduced and the future study is proposed.

• International Journal of Control, Automation, and Systems
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• 제3권3호
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• pp.453-460
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• 2005

In this paper, a prototype Cartesian Parallel Manipulator (CPM) is demonstrated, in which a moving platform is connected to a fixed frame by three PRRR limbs. Due to the orthogonal arrangement of the three prismatic joints, it behaves like a conventional X-Y-Z Cartesian robot. However, because all the linear actuators are mounted at the fixed frame, the manipulator may be suitable for applications requiring high speed and accuracy. Using a geometric method and the practical assumption that three revolute joint axes in each limb are parallel to one another, a simple forward kinematics for an actual model is derived, which is expressed in terms of a set of linear equations. Based on the error model, two calibration methods using full position and length measurements are developed. It is shown that for a full position measurement, the solution for the calibration can be obtained analytically. However, since a ball-bar is less expensive and sufficiently accurate for calibration, the kinematic calibration experiment on the prototype machine is performed by using a ball-bar. The effectiveness of the kinematic calibration method with a ball-bar is verified through the well­known circular test.