Underwater drift tracking system based on maritime positioning platform

An underwater drift tracking system based on a maritime positioning platform, comprising:

• a plurality of underwater drifting objects configured to transmit sound wave signals including their own water depth information by using sound wave communication while drifting underwater;
• and
• a maritime drift tracker configured to track real-time underwater locations of the underwater drifting objects by moving on the sea under its own power, receiving the transmitted sound wave signals from the plurality of underwater drifting objects, and calculating absolute location information of the plurality of underwater drifting objects using the received sound wave signals,
• wherein each of the plurality of underwater drifting objects comprises:
• a power source;
• a water depth sensor configured to measure a water depth;
• and
• a sound wave transmitter configured to transmit a sound wave signal including information on the water depth and voltage of the power source,
• wherein the maritime drift tracker comprises:
• a propulsion circuit configured to generate a propulsive force;
• a launching circuit comprising a storage configured to store a spare underwater drifting object and configured to launch the spare underwater drifting object into water;
• a communication circuit configured to perform communication with external devices via a maritime communication network;
• a GPS receiver configured to receive GPS signals and generate absolute location information of the maritime drift tracker;
• a sound wave tracker installed at a lower part of the maritime drift tracker and configured to receive the transmitted sound wave signals;
• and
• a controller configured to calculate the absolute location information of the plurality of underwater drifting objects by using the absolute location information of the maritime drift tracker, the sound wave signals, and the water depth, and
• wherein the controller is configured to calculate the absolute location information of each of the plurality of underwater drifting objects using mathematical expressions below:
• x
• ′
• =
• x
• +
• Δ
• ⁢
• x
• y
• ′
• =
• y
• +
• Δ
• ⁢
• y
• z
• ′
• =
• Δ
• ⁢
• z
• ,
• where (x′, y′, z′) are absolute location coordinates of the underwater drifting object, (x, y, z) are absolute location coordinates of the maritime drift tracker, Δx and Δy are distances between the maritime drift tracker and the underwater drifting object on the x-axis and y-axis, respectively, and Δz is a water depth of the underwater drifting object.