• Title/Summary/Keyword: Sonar image simulation

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Study on Seabed Mapping using Two Sonar Devices for AUV Application (복수의 수중 소나를 활용한 수중 로봇의 3차원 지형 맵핑에 관한 연구)

  • Joe, Hangil;Yu, Son-Cheol
    • The Journal of Korea Robotics Society
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    • v.16 no.2
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    • pp.94-102
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    • 2021
  • This study addresses a method for 3D reconstruction using acoustic data with heterogeneous sonar devices: Forward-Looking Multibeam Sonar (FLMS) and Profiling Sonar (PS). The challenges in sonar image processing are perceptual ambiguity, the loss of elevation information, and low signal to noise ratio, which are caused by the ranging and intensity-based image generation mechanism of sonars. The conventional approaches utilize additional constraints such as Lambertian reflection and redundant data at various positions, but they are vulnerable to environmental conditions. Our approach is to use two sonars that have a complementary data type. Typically, the sonars provide reliable information in the horizontal but, the loss of elevation information degrades the quality of data in the vertical. To overcome the characteristic of sonar devices, we adopt the crossed installation in such a way that the PS is laid down on its side and mounted on the top of FLMS. From the installation, FLMS scans horizontal information and PS obtains a vertical profile of the front area of AUV. For the fusion of the two sonar data, we propose the probabilistic approach. A likelihood map using geometric constraints between two sonar devices is built and a monte-carlo experiment using a derived model is conducted to extract 3D points. To verify the proposed method, we conducted a simulation and field test. As a result, a consistent seabed map was obtained. This method can be utilized for 3D seabed mapping with an AUV.

A quantitative analysis of synthetic aperture sonar image distortion according to sonar platform motion parameters (소나 플랫폼의 운동 파라미터에 따른 합성개구소나 영상 왜곡의 정량적 분석)

  • Kim, Sea-Moon;Byun, Sung-Hoon
    • The Journal of the Acoustical Society of Korea
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    • v.40 no.4
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    • pp.382-390
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    • 2021
  • Synthetic aperture sonars as well as side scan sonars or multibeam echo sounders have been commercialized and are widely used for seafloor imaging. In Korea related research such as the development of a towed synthetic aperture sonar system is underway. In order to obtain high-resolution synthetic aperture sonar images, it is necessary to accurately estimate the platform motion on which it is installed, and a precise underwater navigation system is required. In this paper we are going to provide reference data for determining the required navigation accuracy and precision of navigation sensors by quantitatively analyzing how much distortion of the sonar images occurs according to motion characteristics of the platform equipped with the synthetic aperture sonar. Five types of motions are considered and normalized root mean square error is defined for quantitative analysis. Simulation for error analysis with parameter variation of motion characteristics results in that yaw and sway motion causes the largest image distortion whereas the effect of pitch and heave motion is not significant.

The Analysis of Parallel Processing Methods for Sonar Imaging Simulation (소나 영상 시뮬레이션 위한 병렬처리 기술 분석)

  • Lee, Keon-Pyo;Ha, Ok-Kyoon;Jun, Yong-Kee
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2017.01a
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    • pp.39-40
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    • 2017
  • 소나 영상 시뮬레이션은 실시간 처리를 위해 병렬처리를 사용하여 연산성능을 증대시키고 있다. 하지만 모듈 간 병렬처리, 영상처리 알고리즘, 방대한 데이터 처리와 같은 시뮬레이션에 적용되는 작업은 성능향상을 위한 최적의 연산장치와 병렬처리 기법이 달라 실시간 처리를 위한 최적화가 어렵다. 본 논문에서는 효율적인 소나 영상 시뮬레이션의 개발을 위해 연산장치 및 병렬처리 기법에 따른 기술을 분류하고 실제 적용된 사례들을 소개한다.

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A Study on Application Method of Parallel Processing for Performance Improvement of Sonar-based Undersea Simulation (소나 기반 해저 시뮬레이션의 성능 향상을 위한 병렬처리 적용 방법 연구)

  • Back, Seoung-Jea;Lee, Keon-Pyo;Ha, Ok-Kyoon
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2018.07a
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    • pp.1-2
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    • 2018
  • 해상 선박의 안전을 위해 해저의 객체 및 장애물의 정확한 탐지를 위해 해저환경에서 감쇠현상이 비교적 적은 음파 기반의 소나가 널리 활용된다. 그러나 기존의 소나 영상 시뮬레이션은 고해상도의 영상, 잡음 처리, 해저지형과 객체 데이터 등의 방대한 데이터 처리로 인해 물체 탐지 및 식별을 위한 처리속도와 비용이 크게 증가한다. 이러한 문제를 최소화하기 위해서 해저지형, 객체 생성과 잡음 처리 모델을 Multi-Threading, SIMD 등 병렬처리를 적용하여 처리속도를 최적화 한다. 본 논문에서는 혼합된 병렬처리 방법을 적용하여 소나를 기반으로 해저 환경 시뮬레이션을 위한 모의 신호를 생성하는 성능을 향상시킨다. 병렬처리로 인해 개선된 성능을 순차처리에 따른 속도와 실험적으로 비교한다.

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A correction of synthetic aperture sonar image using the redundant phase center technique and phase gradient autofocus (Redundant phase center 기법과 phase gradient autofocus를 이용한 합성개구소나 영상 보정)

  • Ryue, Jungsoo;Baik, Kyungmin
    • The Journal of the Acoustical Society of Korea
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    • v.40 no.6
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    • pp.546-554
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    • 2021
  • In the signal processing of synthetic aperture sonar, it is subject that the platform in which the sensor array is installed moves along the straight line path. In practical operation in underwater, however, the sensor platform will have trajectory disturbances, diverting from the line path. It causes phase errors in measured signals and then produces deteriorated SAS images. In this study, in order to develop towed SAS, as tools to remove the phase errors associated with the trajectory disturbances of the towfish, motion compensation technique using Redundant Phase Center (RPC) and also Phase Gradient Autofocus (PGA) method is investigated. The performances of these two approaches are examined by means of a simulation for SAS system having a sway disturbance.

Numerical modeling and simulation technique in time-domain for multibeam echo sounder

  • Jung, Donghwan;Kim, Jeasoo;Byun, Gihoon
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.2
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    • pp.225-234
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    • 2018
  • A Multibeam Echo Sounder (MBES) is commonly used for rapid seafloor mapping. We herein present a time-domain integrated system simulation technique for MBES development. The Modeling and Simulation (M&S) modules consist of four parts: sensor array signal transmission, propagation and backscattering modeling in the ocean environment, beamforming of the received signals, and image processing. Also, the simulation employs a ray-theory-based algorithm to correct the reconstructed bathymetry, which has errors due to the refraction caused by the vertical sound velocity profile. The developed M&S technique enables design parameter verification and system parameter optimization for MBES. The framework of this technique can also be potentially used to characterize the seabed properties. Finally, typical seafloor images are presented and discussed.

Real-time Data Enhancement of 3D Underwater Terrain Map Using Nonlinear Interpolation on Image Sonar (비선형 보간법을 이용한 수중 이미지 소나의 3 차원 해저지형 실시간 생성기법)

  • Ingyu Lee;Jason Kim;Sehwan Rho;Kee–Cheol Shin;Jaejun Lee;Son-Cheol Yu
    • Journal of Sensor Science and Technology
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    • v.32 no.2
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    • pp.110-117
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    • 2023
  • Reconstructing underwater geometry in real time with forward-looking sonar is critical for applications such as localization, mapping, and path planning. Geometrical data must be repeatedly calculated and overwritten in real time because the reliability of the acoustic data is affected by various factors. Moreover, scattering of signal data during the coordinate conversion process may lead to geometrical errors, which lowers the accuracy of the information obtained by the sensor system. In this study, we propose a three-step data processing method with low computational cost for real-time operation. First, the number of data points to be interpolated is determined with respect to the distance between each point and the size of the data grid in a Cartesian coordinate system. Then, the data are processed with a nonlinear interpolation so that they exhibit linear properties in the coordinate system. Finally, the data are transformed based on variations in the position and orientation of the sonar over time. The results of an evaluation of our proposed approach in a simulation show that the nonlinear interpolation operation constructed a continuous underwater geometry dataset with low geometrical error.

A study on development of simulation model of Underwater Acoustic Imaging (UAI) system with the inclusion of underwater propagation medium and stepped frequency beam-steering acoustic array

  • L.S. Praveen;Govind R. Kadambi;S. Malathi;Preetham Shankpal
    • Ocean Systems Engineering
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    • v.13 no.2
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    • pp.195-224
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    • 2023
  • This paper proposes a method for the acoustic imaging wherein the traditional requirement of the relative movement between the transmitter and target is overcome. This is facilitated through the beamforming acoustic array in the transmitter, in which the target is illuminated by the array at various azimuth and elevation angles without the physical movement of the acoustic array. The concept of beam steering of the acoustic array facilitates the formation of the beam at desired angular positions of azimuth and elevation angles. This paper substantiates that the combination of illumination of the target from different azimuth and elevation angles with respect to the transmitter (through the beam steering of beam forming acoustic array) and the beam steering at multiple frequencies (through SF) results in enhanced reconstruction of images of the target in the underwater scenario. This paper also demonstrates the possibility of reconstruction of the image of a target in underwater without invoking the traditional algorithms of Digital Image Processing (DIP). This paper comprehensively and succinctly presents all the empirical formulae required for modelling the acoustic medium and the target to facilitate the reader with a comprehensive summary document incorporating the various parameters of multi-disciplinary nature.

Detection of an Object Bottoming at Seabed by the Reflected Signal Modeling (천해에서 해저면 반사파의 모델링을 통한 물체의 탐지)

  • On, Baeksan;Kim, Sunho;Moon, Woosik;Im, Sungbin;Seo, Iksu
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.5
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    • pp.55-65
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    • 2016
  • Detecting an object which is located at seabed is an important issue for various areas. This paper presents an approach to detection of an object that is placed at seabed in the shallow water. A conventional scheme is to employ a side-scan sonar to obtain images of a detection area and to use image processing schemes to recognize an object. Since this approach relies on high frequency signals to get clear images, its detection range becomes shorter and the processing time is getting longer. In this paper, we consider an active sonar system that is repeatedly sending a linear frequency modulated signal of 6~20 kHz in the shallow water of 100m depth. The proposed approach is to model consecutively received reflected signals and to measure their modeling error magnitudes which decide the existence of an object placed on seabed depending on relative magnitude with respect to threshold value. The feature of this approach is to only require an assumption that the seabed consists of an homogeneous sediment, and not to require a prior information on the specific properties of the sediment. We verify the proposed approach in terms of detection probability through computer simulation.

Analysis of Performance of Focused Beamformer Using Water Pulley Model Array (수차 모형 배열을 이용한 표적추정 (Focused) 빔형성기 성능분석)

  • 최주평;이원철
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.5
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    • pp.83-91
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    • 2001
  • This paper proposes the Focused beamforming to estimate the location of target residing near to the observation platform in the underwater environment. The Focused beamforming technique provides the location of target by the coherent summation of a series of incident spherical waveforms considering distinct propagation delay times at the sensor array. But due to the movement of the observation platform and the variation of the underwater environment, the shape of the sensor array is no longer to be linear but it becomes distorted as the platform moves. Thus the Focused beamforming should be peformed regarding to the geometric shape variation at each time. To estimate the target location, the artificial image plane comprised of cells is constructed, and the delays are calculated from each cell where the target could be proximity to sensors for the coherent summation. After the coherent combining, the beam pattern can be obtained through the Focused beamforming on the image plane. Futhermore to compensate the variation of the shape of the sensor array, the paper utilizes the Nth-order polynomial approximation to estimate the shape of the sensor array obeying the water pulley modeling. Simulation results show the performance of the Focused beamforming for different frequency bands of the radiated signal.

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