• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 1호
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• pp.218-223
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• 1999

A piezoelectric flextentional deep-water sonar transducer has been simulated using a coupled FE-BEM. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with extern리 electrical excitation conditions as well as external acoustic pressure loading conditions. Different results are available such as steady-state frequency response for RX and TX, displacement modes, directivity patterns, back-scattering patterns, resonant frequencies, bandwidths, quality factors, transmitting voltage (TV) responses, input receiving sensitivity (RS) responses. White the present barrel-stave typed sonar transducer of the piezoelectric material is being simulated, the external surface of the transducer is modified in order to allow the same water pressure to be applied to the inner and the outer surfaces of the transducer. With this modification for deep-water application, the resonance frequency of the modified flextentional sonar transducer becomes much lower than that of the unmodified flextentional sonar transducer. The results of the present sonar transducer modelling are also compared with those of a commercial package such as ATILA.

• 전자공학회논문지
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• 제51권8호
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• pp.11-19
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• 2014

최근 능동 소나 시스템은 다중 목표물 탐지가 가능하도록 높은 거리 분해능을 얻기 위해 협대역 시스템에서 광대역 시스템으로 발전하고 있다. 하지만, 목표물 탐지 및 파라미터 추정 등의 성능 향상을 위해서는 광대역 신호처리가 요구되며, 이로 인해 연산량의 증가가 불가피하다. 본 논문에서는 hyperbolic frequency modulation (HFM) 펄스를 사용하는 광대역 능동소나 시스템에서 연산량의 증가를 최소화 하면서도 고속으로 목표물의 탐지 및 속도정보 추정을 할 수 있도록, 확장 레플리카를 이용한 광대역 HFM 탐지기 설계 방법을 제안한다. 모의실험을 통해 제안된 방법이 기존의 필터뱅크를 이용한 광대역 소나 탐지기법에 비해 탐지 및 도플러 추정에서 약간의 성능 열화가 있지만, 연산량 측면에서 매우 우수함을 보인다.

• 한국정밀공학회지
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• 제25권2호
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• pp.35-42
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• 2008

This study introduces a robust feature detector for sonar data from a general fixed-type of sonar ring. The detector is composed of a data association filter and a feature extractor. The data association filter removes false returns provided frequently from sonar sensors, and classifies set of data from various objects and robot positions into a group in which all the data are from the same object. The feature extractor calculates the geometries of the feature for the group. We show the possibility of extracting circle feature as well as a line and a point features. The proposed method was applied to a real home environment with a real robot.

• 제어로봇시스템학회논문지
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• 제5권5호
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• pp.593-599
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• 1999

A mobile robot in FMS environment should be able to nevigate itself. Therefore, path planning is necessary for the mobile robot to perform its tasks without being lost. Path planning using a network model gives oprimal paths to every pair of nodes but building this model demands accurate information of environments. In this paper, a method to build a network model using sonar sensors is presented. The main idea is to build a quad tree model by using sonar sensors and convert the model to a network model for path planning. The new method has been implemented on a mobile robot. Experimental results show that the mobile robot constructs an accurate network model using inaccurate sonar data.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.330-330
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• 2002

The combination of Multi-Beam Echo Sounder swath bathymetry and high-resolution towed Sidescan sonar provides a powerful method of examination about hydrographic survey results. In this paper, we investigate the fast method of 3D bathymetric reconstruction with the Digital Sidescan sonar(Benthos SIS 1500) and Shallow Multi-Beam Echo Sounder(Reson Seabat 8125). The Seabat 8125 is a 455KHz high resolution focused Multibeam echo sounder(MBES) system which measures the relative water depth across a wide swath perpendicular to a vessel's track. The Benthos SIS1500 is a chirp(nominal fq. 200KHz) sonar which map the topographical features & sediment texture of ocean bottom using backscattered amplitude. We generates the very large 3D bathymetric texture mapping model with the Helical System's HHViewer and describes additional benefits of combining MBES and Sidescan Sonar imagery, the removal of geometric distortions in the model and a deterministic sounding noise.

• Journal of Mechanical Science and Technology
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• 제15권2호
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• pp.217-224
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• 2001

In this paper, the relocation of a mobile robot is considered such that it enables the robot to determine its position with respect to a global reference frame without any $\alpha$ priori position information. The robot acquires sonar range data from a two-dimensional model composed of planes, corners, edges, and cylinders. Considering individual range as data features, the robot searches the best position where the data features of a position matches the environmental model using a constraint-based search method. To increase the search efficiency, a hypothesize and-verify technique is employed in which the position of the robot is calculated from all possible combinations of two range returns that satisfy the sonar sensing model. Accurate relocation is demonstrated with the results from sets of experiments using sparse sonar data in the presence of unmodeled objects.

• 로봇학회논문지
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• 제12권4호
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• pp.385-394
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• 2017

Side scanning sonar (SSS) provides valuable information for robot navigation. However using the side scanning sonar images in the navigation was not fully studied. In this paper, we use range data, and side scanning sonar images from UnderWater Simulator (UWSim) and propose measurement models in a feature based simultaneous localization and mapping (SLAM) framework. The range data is obtained by echosounder and sidescanning sonar images from side scan sonar module for UWSim. For the feature, we used the A-KAZE feature for the SSS image matching and adjusting the relative robot pose by SSS bundle adjustment (BA) with Ceres solver. We use BA for the loop closure constraint of pose-graph SLAM. We used the Incremental Smoothing and Mapping (iSAM) to optimize the graph. The optimized trajectory was compared against the dead reckoning (DR).

• 수산해양기술연구
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• 제39권2호
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• pp.92-98
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• 2003

소너를 이용한 어군량 조사에서 자동화가 용이하고 고기의 분포상태에 관계없이 측정이 가능한 에코적분법에 관한 정량화법의 기초 연구로서, 소너 화상의 휘도를 2 승 적분하여 어군량을 정량화하고 이 값을 다른 어군량 지표와 비교, 분석한 결과를 요약하면 다음과 같다. 1. 휘도를 이용하여 작성한 에코그램으로부터 어군과 해저를 분명하게 식별하는 것이 가능하여 화상을 이용한 어군량의 정량화에 있어서 휘도는 유용한 정보이다. 2. 소너 화상으로부터 계수법에 의하여 얻어진 어군의 수는 픽셀 휘도의 2승 적분치에 정의 상관을 나타내었으나, 어군의 계수법은 어군의 규모에 관계하지 않고 어군을 계수하기 때문에 오차가 클것으로 판단되어 정량화법으로서는 좋은 방법이라 할 수 없다. 3. 면적측정법으로 계측된 어군면적은 픽셀 휘도의 2승 적분치에 비례하고 유의한 상관을 나타내었으므로, 어군량 지표로서 유용 가능하다고 판단된다. 4. 소너 화상의 휘도를 2 승 적분하여 얻어진 어군량 정보는 고기의 분포상태에 관계없이 측정이 가능하여 어군량을 정량화하는 방법으로서 유용할 것으로 판단된다.

• 로봇학회논문지
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• 제2권3호
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• pp.227-233
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• 2007

Representing an environment as the probabilistic grids is effective to sense outlines of the environment in the mobile robot area. Outlines of an environment can be expressed factually by using the probabilistic grids especially if sonar sensors would be supposed to build an environment map. However, the difficult problem of a sonar such as a specular reflection phenomenon should be overcome to build a grid map through sonar observations. In this paper, the NRF(Neighborhood Recognition Factor) was developed for building a grid map in which the specular reflection effect is minimized. Also the reproduction rate of the gird map built by using NRF was analyzed with respect to a true map. The experiment was conducted in a home environment to verify the proposed technique.

• 한국군사과학기술학회지
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• 제16권2호
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• pp.118-129
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• 2013

Since the obstacles and mines are of the risk factors for operating ships and submarines, the active sonar system is inevitably used to avoid the hazards in ocean environment. In this paper, modeling and simulation algorithm is used for active sonar systemto quantify the measure of mission achievability, which is known as Measure of Effectiveness(MOE), specifically for detection in this study. MOE for detection is directly formulated as a Cumulative Detection Probability(CDP) calculated from Probability of Detection(PD) in range and azimuth. The detection probability is calculated from Transmission Loss(TL) and the sonar parameters such asDirectivity Index (DI) calculated from the shape of transmitted and received array, steered beam patterns, and Reverberation Level (RL). The developed code is applied to demonstrating its applicability.