Improved Hydrographic Surveying Accuracy with the Use of GPS/IMU and Single Beam Echo Sounder ☆

Single beam echo sounders (SBES) mounted on unmanned surface vehicles (USVs) are widely used in hydrographic surveying, particularly for detecting water depth and digital depth mapping, among other things. Because of conditions such as ocean waves, the relative level arm of each component, and errors in each component device, using only SBES and GPS sensors leads to significant errors and poor accuracy. Now the SBES sensor's accuracy has improved. However, this is insufficient. A new real-time kinematic (RTK) positioning technique enables horizontal and vertical coordinate precision of 2 to 5 centimeters. Additionally, the precision of the survey is dependent on the USV's movements. USVs use inertial measurement units (IMUs) to provide information on the system's acceleration, velocity, position, and orientation. To reduce errors and produce trustworthy results, it is necessary to process data from various devices using a well-integrated algorithm. The purpose of this article is to discuss how to develop an algorithm that combines sensors such as GPS RTK/IMU, SBES, and other similar devices. This method takes into account both the rotations and relative level-arm of sensors. Finally, analysis of the data indicates a significant increase in the accuracy of the integrated algorithm when compared to the conventional techniques.