• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.1
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• pp.64-73
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• 2012

In this paper, a new land preview system using laser range finder based on heave estimation algorithm is proposed. The proposed land preview system is an equipment which measures the shape of forward topography for autonomous vehicle. To implement this land preview system, the laser range finder is generally used because of its wide measuring range and robustness under various environmental condition. Then the current location of the vehicle has to be known to generate the shape of forward topography and sensors based on acceleration such as IMU and accelerometer are generally utilized to measure heave motion in the conventional land preview system. However the drawback to these sensors is that they are too expensive for low-cost vehicle such as mobile robot and their measurement error is increased for mobile robot with abrupt acceleration. In order to overcome this drawback, an algorithm that estimates heave motion using the information of odometer and previously measured topography is proposed in this paper. The proposed land preview system based on the heave estimation algorithm is verified through simulation and experiments for various terrain using a simulator and a real system.

• International journal of advanced smart convergence
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• v.3 no.2
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• pp.14-17
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• 2014

Precision agriculture relies on information technology, whose precondition is providing real-time and accurate information. It depends on various kinds of advanced sensors, such as environmental temperature and humidity, wind speed, light intensity, and other types of sensors. Currently, it is a hot topic how to collect accurate information, the main raw data for agricultural experts, monitored by these sensors timely. Most existing work in WSNs addresses their fundamental challenges, including power supply, limited memory, processing power and communication bandwidth and focuses entirely on their operating system and networking protocol design and implementation. However, it is not easy to find the self-localization capability of wireless sensor networks. Because of constraints on the cost and size of sensors, energy consumption, implementation environment and the deployment of sensors, most sensors do not know their locations. This paper provides maximum likelihood estimators for sensor location estimation when observations are time-of arrival (TOA) range measurement.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.554-557
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• 1993

The error analysis for the Time-in-Flight Laser Range Finder with Multiple Tone Amplitude Modulation relevant to the phase detection error is made. The distance can be estimated to solve the formulate which express the relationship between the absolute distance from the range finder to the object and the wavenumbers and the phases of the modulated waves by the optimization technique. The main cause of the estimation error can be considered as the phase detection error induced from the amplitude modulator and the phase detector. To clarify the phase detection error and the optimal amplitude frequency set, the numerical analysis are made.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.334-336
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• 2009

Estimation and correction of color temperature of digital images are basis of white balance adjustment after image acquisition stage. White balance is one of the most important image processing techniques for subjective image quality enhancement. Correction of color temperature is applied for white balance adjustment or for changing the mood of a picture. A picture taken under the daylight can be changed to have a mood of sunset or cloudy day, for example. We evaluate color temperature transformation of high dynamic range images in linear and log domain, and we conclude that linear domain transformation shows better results.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.211-215
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• 2010

This study is on the effective methods for non metric camera calibration for its use in accurate close range photogrammetric surveying. We tested four estimation methods used for calculating interior orientation parameters and two methods for building calibration field, one is using targets which have three dimensional coordinates and the other is using two dimensional grid targets. By analysing test results effective and accurate calibration methods were suggested.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.635-636
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• 2006

A pulse with modulation(PWM) that keeps a constant angle of dwell and adjust duty ratio is a good method to control a speed of SRM. And a method of one pulse control is proper a operation on range of high speed in SRM for a good energy efficiency. Because PWM method is more safety than one pulse method, conversion of those is best choice according the speed range. So, some algorithm is need for smooth conversion of the mode of control. This paper presents a factor of conversion that proper the conversion of control mode between PWM and one pulse method This factor is from estimation of torque and proper at the variable range of conversion and show the better conversion characteristic than constant factor of conversion.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.1
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• pp.41-48
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• 2014

This paper analyzes the Monte Carlo localization (MCL) method, which estimates the pose of an indoor mobile robot. A mobile robot must know where it is to navigate in an indoor environment. The MCL technique is one of the most influential and popular techniques for estimation of robot position and orientation using a particle filter. For the analysis, we perform experiments in an indoor environment with a differential drive robot and ultrasonic range sensor system. The analysis uses MATLAB for implementation of the MCL and investigates the effects of the control parameters on the MCL performance. The control parameters are the uncertainty of the motion model of the mobile robot and the noise level of the measurement model of the range sensor.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.3
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• pp.15-21
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• 2003

This paper contains a precise calibration technique for the position of seabed acoustic target and theoretical error analysis of calibration results. The target is deployed on seabed as a standalone transponder. The purpose of target is performing accuracy test for active sonar as well as position calibration itself. For the position calibration, relative range between target and test vessel should be measured using target's transponder function. The relative range data combined with vessel position can be converted into a estimated position of target by the application of nonlinear LSE method. The error analysis of position calibration was divided into two stages. One is for relative range estimator and the other for target position estimator. Numerical simulations for position calibration showed good matching between results and developed CRLB.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.5
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• pp.420-427
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• 2010

This paper describes a localization method based on Monte Carlo Localization approach for a mobile robot. The method uses range data which are measured from ultrasound transmitting beacons whose locations are given a priori. The ultrasound receiver on-board a robot detects the range from the beacons. The method requires several beacons, theoretically over three. The method proposes a sensor model for the range sensing based on statistical analysis of the sensor output. The experiment uses commercialized beacons and detector which are used for trilateration localization. The performance of the proposed method is verified through real implementation. Especially, it is shown that the performance of the localization degrades as the sensor update rate decreases compared with the MCL algorithm update rate. Though the method requires exact location of the beacons, it doesn't require geometrical map information of the environment. Also, it is applicable to estimation of the location of both the beacons and robot simultaneously.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.233-234
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• 2007

It is needed many images with different exposure to acquire high dynamic range (HDR) image of a scene using digital still camera. This paper proposed to acquire HDR image with small error using reduced number of image. Proposed method takes two pictures with different exposure and estimates dynamic range of scene using information two images, and takes three pictures with calculated proper exposure to acquire HDR image.