Ship Disturbance Estimation Using Thrust and Navigation Data

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Solution Overview

Problem

Existing systems struggle to accurately estimate disturbances acting on marine vessels, such as those caused by tidal currents and wind, which interfere with stable ship control, making it difficult to maintain a fixed position or desired heading.

Innovation Solution

A disturbance estimation apparatus using a navigation data receiver, thrust data receiver, and processing circuitry to estimate a predicted ship position under disturbance-free conditions, determining drift direction and speed based on a state estimation model, and optionally incorporating anemometer and tidal current meter data to refine predictions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If position information from GNSS is used to control the ship, then navigation capability is provided, but disturbance cannot be accurately estimated because it is difficult to distinguish thrust-induced movement from disturbance-induced movement

Engineering Contradiction:

Improvedisturbance estimation accuracyVSAvoidinability to distinguish thrust effect from disturbance effect

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent introduces an intermediary computational model (equation of motion) that processes both thrust data and position data to separate their effects. The model acts as a mediator that decomposes the composite movement into thrust-induced components and disturbance-induced components, enabling accurate disturbance estimation while maintaining navigation capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct mechanical measurement of disturbance with a computational approach using equations of motion. Instead of physically measuring disturbance forces, the system uses mathematical modeling to calculate disturbance effects by substituting observed position changes and known thrust inputs into the ship's equation of motion, thereby deriving disturbance as the residual effect.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If disturbance estimation is performed using only position information, then the system remains simple, but the estimation accuracy deteriorates due to inability to separate thrust and disturbance effects

Engineering Contradiction:

Improvesystem structure simplicityVSAvoiddisturbance estimation accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent makes the processing circuitry multi-functional by enabling it to perform both navigation (position tracking) and disturbance estimation using the same hardware components. The circuitry processes thrust data, position data, and equation of motion calculations universally, eliminating the need for separate dedicated disturbance measurement devices while maintaining high estimation accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the ship operates in disturbed conditions (wind, waves, current), then navigation challenges increase, but the system can adapt by estimating disturbance to improve control

Engineering Contradiction:

Improvecontrol performance under disturbanceVSAvoidwave forces, air forces, tidal currents

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the estimated disturbance is continuously fed back to the control system. The processing circuitry calculates disturbance based on the equation of motion and feeds this information back to adjust hull control, enabling the system to adapt to changing disturbance conditions and maintain stable navigation despite wave forces, air forces, and tidal currents.

Inventive Principle:

Principle #23Feedback

4Productivity

If disturbance is not estimated accurately, then control adjustments are delayed, but the system can respond faster by implementing real-time disturbance estimation

Engineering Contradiction:

Improvenavigation efficiencyVSAvoidcontrol response time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent performs preliminary disturbance estimation by continuously calculating the equation of motion and predicting disturbance effects before they significantly impact navigation. The system proactively estimates disturbance based on current thrust and position data, allowing control adjustments to be made in advance, thereby improving navigation efficiency without losing response time.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12392613B2Disturbance estimating apparatus, method, and computer program

Publication Date: 2025.08.19 FURUNO ELECTRIC CO LTD

AI summary

A disturbance estimation apparatus including a navigation data receiver, a thrust data receiver, and processing circuitry is provided. The navigation data receiver acquires navigation data including an actual position and time of the ship on a water surface. The thrust data receiver receives thrust data indicating a magnitude and a direction of a thrust force of the ship. The processing circuitry estimates a predicted position of the ship under an absence of a disturbance condition at a predetermined time in the future using a first state estimation model based on the navigation data and the thrust data and determines disturbance data including a drift direction of the ship drifted by an external force based on a difference between the predicted position estimated by the first state estimation model and an actual position of the ship at the predetermined time.