Ship Speed Control Using Throttle Upper Limits at Low Speed

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Solution Overview

Problem

Conventional ship speed control methods result in sudden speed changes when increasing ship speed settings exceed actual ship speed, leading to undesirable throttle increases.

Innovation Solution

A ship speed control device and method that calculates a throttle command value based on the difference between actual and target ship speeds, restricting throttle increases to prevent sudden changes by setting a throttle upper limit and adjusting integral gains in PID control, ensuring smooth acceleration from low to high speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the ship speed setting is increased too high while actual ship speed is low, then the target ship speed increases rapidly, but the actual ship speed changes suddenly causing unstable control

Engineering Contradiction:

Improvetarget ship speedVSAvoidship speed stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The system performs preliminary action by setting a throttle upper limit before the actual ship speed can respond to a high target speed setting. This prevents the throttle from being sharply increased when the target speed is set high while actual speed is low, thereby avoiding sudden speed changes and maintaining control stability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the throttle command value based on the relationship between actual ship speed and target ship speed. When actual speed is below a first threshold and throttle calculation value exceeds the upper limit, the throttle command is restricted; when actual speed reaches the threshold, the restriction is cancelled. This dynamic adjustment resolves the contradiction between rapid speed response and stability

Inventive Principle:

Principle #15Dynamics

2Productivity

If the throttle opening is sharply increased to achieve high speed quickly, then the target ship speed is reached faster, but the acceleration becomes sudden and undesirable

Engineering Contradiction:

Improvespeed response timeVSAvoidacceleration smoothness

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The system sets a throttle upper limit as a preliminary constraint before speed control begins. This prevents sharp throttle increases even when high speed is urgently needed, ensuring smooth acceleration while still allowing the system to respond to speed changes within the established limits

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors actual ship speed and compares it with the target speed to calculate a throttle calculation value. This feedback mechanism ensures that throttle adjustments are proportional to the actual speed difference, preventing sudden acceleration while maintaining effective speed response

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3798111B1Ship speed control device, ship speed controlling method, and ship speed control program

Publication Date: 2023.01.18 FURUNO ELECTRIC CO LTD

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AI summary

A ship speed control device (22) is provided, which includes a calculator (223) and a throttle command value setter (224). The calculator (223) calculates a throttle calculation value (Re) based on a difference between an actual ship speed (V) and a target ship speed (Vt). The throttle command value setter (224) sets, when the actual ship speed (V) is below a first threshold (THs) determined based on a given throttle upper limit (Rs) and the throttle calculation value (Re) is at or above the throttle upper limit (Rs), a throttle command value (R) to the throttle upper limit (Rs).