A Study for Optimum Survey Method of Underwater Structure Using the Dual Sonar Sensor

Abstract

We have developed dual sonar equipment and an improved operating method for improving resolution in order to solve the problems of limitations of the optical equipment and the application method of SSS (side scan sonar) in the investigation of damage of underwater structures. We analyzed the influence factors of the resolution of sonar data through the comparison of resolution and data quality in indoor test. Also we confirmed the problems about the overlapping area of the dual sonar. Depth and distance were analyzed as major influencing factors for survey angle. Specimens were scanned while adjusting distance and towfish angle according to depth change in order to verify applicability of the developed dual sonar in the field experiment. Optimal resolution was found to be 3 cm in specimen spacing, and 20 sample data items were extracted. We developed the regression model based on the multiple regression analysis and developed the RealDualSONAR-DAQ tool, the dual sonar optimum operating method program based on proposed correlation equations. We can use the developed tools to get the value of the major influencing factors for dual sonar operation and obtain high quality sonar data to analyze damage of underwater structures.

A Study of Sonar Image Stabilization of Unmanned Surface Vehicle Based on Motion Sensor for Inspection of Underwater Infrastructure

“…The experiment was conducted by comparing the errors, according to the frequency specification of the sonar. The resolution of the sonar data can be varied according to the influencing factors, such as the beam angle, the distance to the structure, and the depth of the water [4]. It also might need to be considered about specifying the level of precision of GPS or motion sensor and in which percentage this error could affect the measurements.…”

“…In the case of ROV, depending on the mission, some ROV are equipped with a sonar or laser scanner, but it is normally used with optical equipment and the imaging sonar. Generally, it is difficult to control in especially underwater condition in where the tide and turbidity is relatively high [1,4]. For this problem, it is possible to use a motor with high thrust, but the size of the ROV body and battery capacity should be considered.…”

Survey methods for seaport waterworks on the example of the Balaklava Bay objects

“…The standard list of works on the engineering survey of PHS includes instrumental and visual control of structural elements of structures in the surface and underwater zones. The technical condition of the structures is primarily determined on the basis of instrumental operations: geodesic survey with electronic high-precision instruments, determination of concrete strength by direct and indirect methods, visual surface and underwater (diving) inspection to identify defects and damages, depth measurements, etc [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. However, there are a number of difficulties, which does not allow to assess the technical condition qualitatively with the use of traditional survey methods.…”

Development of a 2 MHz Sonar Sensor for Inspection of Bridge Substructures

“…However, since ROVs are mostly used with optical equipment, they are difficult to apply in Korean waters where the turbidity is high and the tides are strong. In addition, since 1 MHz Side Scan Sonar (SSS) is mainly used in towing type equipment for surveying river beds, it is difficult to adjust the angles, and it is not suitable for direct application to the survey of damage to underwater structures due to its low resolution [ 2 ].…”