Ship Throttle Search Initialization for Accurate Dynamic Positioning

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Solution Overview

Problem

Conventional ship control techniques using model predictive control face challenges in achieving high prediction accuracy, which affects the reliability of ship positioning and dynamic positioning.

Innovation Solution

The ship control system employs a processing circuitry that estimates an initial search value for the throttle opening using an uncertainty-based estimation method, incorporating distance and true wind velocity as preconditions. This initial search value is then used in model predictive control to determine the command throttle opening, improving prediction accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If model predictive control is used for ship positioning, then automation and control capability are improved, but prediction accuracy deteriorates

Engineering Contradiction:

Improveautomatic ship controlVSAvoidprediction accuracy

Core Design Contradiction:

Extent of automationVSMeasurement precision

Solution Approach 1:

The system performs preliminary estimation of the initial search value for throttle opening using uncertainty-based methods (fuzzy inference) before executing model predictive control. This preliminary action provides a more accurate starting point for the MPC search, improving overall prediction accuracy while maintaining automation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary estimation process that acts as a bridge between raw sensor data and the model predictive control algorithm. The uncertainty-based estimation method processes distance and wind velocity information to generate an initial throttle opening value, which then feeds into the MPC system, enhancing its prediction capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the search range for throttle opening is widened to improve control flexibility, then adaptability is improved, but calculation time and complexity increase

Engineering Contradiction:

Improvecontrol flexibilityVSAvoidcalculation time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

Instead of using a uniform wide search range, the system applies local quality by concentrating the search around the estimated initial value. The search range is adapted locally based on the uncertainty estimation, providing sufficient flexibility where needed while reducing unnecessary calculations in less relevant areas.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts the search range parameters based on the estimated initial value and uncertainty levels. By changing the search parameters adaptively rather than using fixed wide ranges, the system maintains control flexibility while reducing calculation time through more focused search boundaries.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12339662B2Ship control device, ship control method, and ship control program

Publication Date: 2025.06.24 FURUNO ELECTRIC CO LTD

AI summary

To improve prediction accuracy in model predictive control.The ship control device includes processing circuitry. The processing circuitry estimates an initial search value of a throttle opening by an estimation method based on uncertainty with a distance between a position of the ship and a target position of dynamic positioning, and a true wind velocity as preconditions. The processing circuitry searches an action for moving the ship to the target position by a model predictive control in a search range having the initial search value as an origin, and determines a command throttle opening based on the search result.