Patent ID: 11964745
Assignee: KAWASAKI JUKOGYO KABUSHIKI KAISHA
Field: Measurement (Instruments)
Classification: CPC B  G | IPC B  G

Claim 3:
4. An underwater work system comprising:
a surface ship located on water;
a transponder dropped from the surface ship to a bottom of the water; and
an underwater vehicle that includes a relative speed indicator that measures a relative speed of the underwater vehicle relative to the bottom of the water, and performs searching work of finding a pipeline laid on the bottom of the water based on the dropped transponder;
a wave transmitter that is mounted on the surface ship and transmits a sound wave used to measure a relative position of the transponder relative to the surface ship; and
circuitry configured to
acquire the relative position of the transponder relative to the surface ship at the start of the searching work, the relative position being measured based on the sound wave transmitted from the wave transmitter,
calculate a position of the transponder based on the acquired relative position, when a measurement error region whose center corresponds to the calculated dropped position of the transponder and an expected laid region of the pipeline extending in a predetermined direction overlap each other, set, as a target position, such a provisional dropped position of the transponder that the measurement error region and the expected laid region do not overlap each other,
after the underwater vehicle is moved to the dropped position of the transponder, move the underwater vehicle until the position of the underwater vehicle reaches the target position, while calculating a relative position of the underwater vehicle relative to the transponder based on the relative speed of the underwater vehicle relative to the bottom of the water acquired from the relative speed indicator, and
then make the underwater vehicle perform crossing detection in which the underwater vehicle detects the presence or absence of the pipeline while crossing the expected laid region.