A novel ocean bathymetry technology based on an unmanned surface vehicle

In ocean bathymetry, the instantaneous depth measured by survey ships or by unmanned surface vehicles (USVs) cannot be directly taken as the chart depth because of the effect of waves and the tide. A novel ocean bathymetry technology is proposed based on the USV, the aim is to evaluate the potential of the USV using a real-time kinematic (RTK) and a single beam echo sounder for ocean bathymetry. First, using the RTK height of the USV with centimeter-level precision, the height of the sea level is obtained by excluding wave information using a low pass filter. Second, the datum distance between the reference ellipsoid and the chart depth is obtained by a novel method using tide tables and the height of the sea level from the USV. Previous work has usually achieved this using long-term tidal observation from traditional investigations. Finally, the chart depth is calculated using the transformation between the instantaneous depth of the USV measurement and the datum of the chart depth. Experiments were performed around the Wuzhizhou Island in Hainan Province using the unmanned surface bathymetry vehicle to validate the proposed technology. The successful results indicate the potential of the bathymetry technology based on the USV.