Ship Surface Current Estimation Using Propeller and Wind Data

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Solution Overview

Problem

Existing methods for estimating surface current velocity in ocean surface zones are either computationally intensive or fail to measure currents near the sea surface, which significantly affect ship movement, and require large-scale installation work for speed log installation.

Innovation Solution

A surface current estimating device that uses a neural network-based estimator to calculate log velocity vectors from propeller rotational speed and wind direction/wind speed data, eliminating the need for large-scale installation work by utilizing existing ship equipment like propeller speed detectors and vane anemometers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Fourier transform is applied on reception signals from ocean radar to obtain surface current velocity, then the surface current velocity can be obtained, but the calculation load becomes high and calculation time becomes long

Engineering Contradiction:

Improvesurface current velocity measurementVSAvoidcalculation speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces the complex signal processing method (Fourier transform on radar reception signals) with a simpler calculation approach using basic velocity vector relationships. Instead of applying heavy computational algorithms to radar data, the invention uses direct mathematical relationships between ground velocity, log velocity, and current velocity, significantly reducing calculation load and processing time while maintaining measurement accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If ultrasonic current meter is used to measure surface current, then current measurement is possible, but only current below the instrument is measured and shallow layer current affecting ship movement cannot be measured

Engineering Contradiction:

Improvecurrent measurement capabilityVSAvoidmeasurement coverage

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent uses the ship itself as an intermediary measurement platform. By measuring the ship's ground velocity through GPS and comparing it with the ship's velocity through water (log velocity) calculated from propeller speed and wind data, the system indirectly measures the surface current velocity. This approach captures the current that actually affects ship movement in the shallow layer, which is the critical information needed for navigation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If speed log is installed on ship bottom to measure log velocity, then accurate water speed measurement is possible, but large-scale installation work such as forming hole in ship bottom is required

Engineering Contradiction:

Improvelog velocity measurement accuracyVSAvoidinstallation complexity

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent makes the ship serve itself as the measurement instrument. By utilizing existing ship equipment (propeller speed detector, vane anemometer, GPS receiver) and applying appropriate calculations, the system obtains log velocity without requiring external installation of speed logs or other specialized measurement devices. The ship's own operational parameters are used to derive the measurement data.

Inventive Principle:

Principle #25Self-service

4Measurement precision

If additional instruments are equipped to detect log velocity vector, then accurate log velocity measurement is possible, but device complexity and cost increase

Engineering Contradiction:

Improvelog velocity vector detectionVSAvoidinstrumentation requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes existing multi-functional ship equipment serve additional measurement purposes. The propeller speed detector, originally designed for propulsion control, is used to infer water speed. The vane anemometer, designed for weather observation, is used to correct the velocity calculation. The GPS receiver, designed for position tracking, provides ground velocity for current calculation. This multi-functional use of existing equipment eliminates the need for dedicated log velocity measurement instruments.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3112877B1Surface current estimation device, surface current estimation system, ocean model estimation device, and risk determination device

Publication Date: 2018.07.18 FURUNO ELECTRIC CO LTD

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AI summary

A velocity of a surface current is easily calculated. A surface current estimating device la is provided, which includes a ground velocity calculating module (11) configured to calculate a ground velocity vector of a ship at a target location where the ship is located on the sea, an estimator (12a) configured to receive an input of one or more values of at least one parameter at the target location, and estimate and output, as a log velocity vector of the ship, a value corresponding to one of conditions, the at least one parameter causing an influence on the log velocity vector of the ship, each of the conditions defined by a combination of the received values, and a surface current calculating module (13) configured to calculate the surface current velocity vector of the target location, based on the output value as the log velocity vector estimated by the estimator (12a) and the ground velocity vector calculated by the ground velocity calculating module (11).