Implementation of Digital IMU for Increasing the Accuracy of Hydrographic Survey

Hydrographic survey is of great importance in many fields. The accuracy of the survey has a huge dependency on the sea condition, which is the main parameter of the vessel's motion. Modern vessels use inertial measurement units to track the motion and compensate its effect. However, it is still under development as an optimum solution is yet to be found. Most of the techniques require special “ground markings” and complex procedures. Companies which use IMUs did not reveal their technology. Moreover, they use special kind of IMUs which are very expensive and bulky. In this paper, low cost digital Inertial Measurement Units (IMU) are used to determine the vessel's rotational motions and a general expression is derived from scratch for the correction of depth and position data in real-time, which is incorporated with a simple working algorithm. This compensation will enable the survey vessels to work under harsh weather. Focus is given on the roll and pitch motion as these two have the prime effect on the measurement and cannot be not detected using GPS.