• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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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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• v.17 no.12
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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.

• Journal of Korean Society of Rural Planning
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• v.21 no.4
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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.

• Annual Conference of KIPS
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• 2013.11a
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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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.8
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• pp.11-23
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• 2000

Head-eye calibration is a process for estimating the unknown orientation and position of a camera with respect to a mobile platform, such as a robot wrist. We present a new head-eye calibration technique which can be applied for platforms with rather limited motion capability In particular, the proposed calibration technique can be applied to find the relative orientation of a camera mounted on a linear translation platform which does not have rotation capability. The algorithm find the rotation using a calibration data obtained from pure Translation of a camera along two different axes We have derived a calibration algorithm exploiting the rectification technique in such a way that the rectified images should satisfy the epipolar constraint. We present the calibration procedure for both the rotation and the translation components of a camera relative to the platform coordinates. The efficacy of the algorithm is demonstrated through simulations and real experiments.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.69-80
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• 2019

This paper proposes a multimodal sensor platform which supports plug and play (PnP) technology. PnP technology automatically recognizes a connected sensor module and an application program easily controls a sensor. To verify a multimodal platform for PnP technology, we build up a firmware and have the experiment on a sensor system. When a sensor module is connected to the platform, a firmware recognizes the sensor module and reads sensor data. As a result, it provides PnP technology to simply plug sensors without any software configuration. Measured sensor raw data suffer from various distortions such as gain, offset, and non-linearity errors. Therefore, we introduce a polynomial calculation to compensate for sensor distortions. To find the optimal coefficients for sensor calibration, we apply a genetic algorithm which reduces the calibration time. It achieves reasonable performance using only a few data points with reducing 97% error in the worst case. The platform supports various protocols for multimodal sensors, i.e., UART, I2C, I2S, SPI, and GPIO.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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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.

• Proceedings of the KSME Conference
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• 2000.11a
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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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• v.3 no.3
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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.