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Polarimetric Underwater Positioning System

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Visible-Light 3D Underwater Positioning

This visible-light three-dimensional positioning system is designed for underwater robots, marine engineering facilities, and short-range precision operations. It combines blue/green polarized LED beacons, a pressure-rated polarimetric vision receiver, and positioning software. The system detects known beacons and applies camera calibration, refraction compensation, and PnP pose estimation to output the receiver's three-dimensional coordinates (X, Y, Z) and orientation.

Beacon color and polarization are jointly processed to address limited visibility, ambient illumination, scattering, and platform motion. The MER2-503-23GC-P POL camera captures 0°, 45°, 90°, and 135° color-polarization components in one exposure, reinforcing weak beacon features while suppressing non-target backgrounds. The camera is integrated in a cylindrical 316 stainless-steel housing with an optical window and watertight connector. Rated to 300 m, the compact GigE/PoE receiver is suitable for ROVs, AUVs, inspection tools, wall-crawling systems, and fixed platforms.

Operating concept of the pressure-rated polarimetric vision underwater positioning system

Product Features

Centimeter-Level Positioning

Mean position error below 6 cm and mean orientation error below 1.5° at 10 m.

Reliable Beacon Detection

F1 score above 0.98 at a 7 m beacon-to-receiver distance.

Strong Ambient-Light Tolerance

Polarization and color-channel processing enhance weak beacons and suppress background, scattering, and water-surface disturbance.

Single-Camera Polarization Imaging

Four color-polarization directions (0°, 45°, 90°, 135°) acquired in one exposure.

300 m Pressure-Rated

316 stainless-steel housing, optical window, and watertight connector for subsea engineering operations.

Low Latency, Easy Integration

GigE/PoE and GPIO connect directly to robotic computing platforms; IMU assistance supports fewer visible beacons.

System Components

The system uses blue/green polarized LED beacons as surveyed optical references. The receiver integrates a Mercury 2 color polarization camera, lens, mounting structure, optical window, and sealed electrical connection inside a 316 stainless-steel pressure housing.

Upgraded polarimetric vision receiver

Upgraded Receiver

Complete receiver assembly with watertight cable

Complete Assembly

Polarized LED beacon and representative blue/green operating states

Polarized LED Beacon — Blue/Green Operating States

Cutaway visualization of the polarization camera installed inside the 300 m pressure housing

Polarization Camera Inside The 300 m Pressure Housing

Technical Specifications

Positioning output3D coordinates (X, Y, Z) and orientation; camera calibration, refraction compensation, beacon identification, and PnP estimation supported
Positioning performanceMean position error < 6 cm and mean orientation error < 1.5° at 10 m
Maximum operating depth300 m
Polarization cameraDaheng Imaging MER2-503-23GC-P POL, Mercury 2 series, color polarization
Sensor and shutterSony IMX264MYR-C, 2/3-inch global-shutter CMOS
Resolution2448(H) × 2048(V), ~5 megapixels; 3.45 µm × 3.45 µm pixel size
Polarization channelsSimultaneous 0°, 45°, 90°, 135° acquisition; max frame rate 23.5 fps
Data and powerGigE PoE; 12 VDC -10% to 24 VDC +10%, or PoE compliant with IEEE 802.3af
Camera power< 3 W at 24 VDC; < 3.75 W via PoE
Camera body29 mm × 29 mm × 40.3 mm excluding lens interface and connectors; 75 g; C/CS lens mount
Pressure housing316 stainless-steel body, ~57 mm outer diameter and 187.5 mm main-body length, with front optical-glass window
Camera operating temperature0°C to 45°C

Tested Environments

Land, pool, and robot-tracking test environments