Watercraft Vertical Movement Control via Resonance Range Adjustment
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Solution Overview
Problem
Existing methods for reducing vertical movement in watercraft, such as cargo ships and submarines, often require unnecessary control and drive interventions due to large resonance ranges, which can lead to increased rolling vibrations and instability, compromising safety and comfort.
Innovation Solution
A method that continuously determines the vertical movement resonance range and adjusts the watercraft's speed and course to exit this range, using sensors and actuators to minimize vertical movements, thereby reducing rolling vibrations and enhancing safety and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonance range is determined by prior estimation of the ship's roll time and knowledge of its natural roll period, then the risk of parametric roll resonance can be reduced, but the determined resonance range is so large that unnecessary steering and propulsion interventions are sometimes performed
Solution Approach 1:
The patent changes the parameters used to determine resonance range from general ship characteristics (roll period, natural frequency) to specific motion state parameters (encounter frequency, wave parameters, heel angle, acceleration). By continuously monitoring these dynamic parameters and determining resonance range based on actual motion state rather than static ship characteristics, the method achieves more precise resonance detection with smaller, more accurate resonance ranges, reducing false alarms and unnecessary interventions.
Solution Approach 2:
The patent replaces the traditional mechanical estimation method (based on ship's roll period and natural frequency) with a sensor-based measurement system that directly measures motion parameters (acceleration, heel angle, pitch angle) and wave parameters. This substitution of direct measurement for theoretical estimation enables more accurate determination of the actual resonance range in real-time conditions.
2Reliability
If steering and propulsion interventions are performed to clear the resonance range, then vertical motion can be reduced or prevented from increasing, but the planned course of travel must be deviated from and total travel time increases
Solution Approach 1:
The patent continuously monitors motion parameters and wave conditions to detect resonance conditions before they lead to dangerous rolling. By determining resonance range based on actual motion state and encounter frequency, the system can take preliminary corrective actions (speed or course adjustments) when entering the resonance range, preventing dangerous oscillations from developing while minimizing the duration and magnitude of interventions required.
Solution Approach 2:
The patent applies partial action by making minimal, targeted adjustments to speed or course only when and where necessary to exit the resonance range. The resonance range determination based on actual motion state allows for more precise targeting of corrective actions, avoiding excessive or prolonged deviations from the planned course that would unnecessarily increase travel time.
3Ease of manufacture
If the resonance range is determined by prior estimation methods, then the method is simple to implement, but the resonance range is so large that it compromises precision and leads to over-intervention
Solution Approach 1:
The patent replaces simple theoretical estimation with sensor-based direct measurement of motion parameters (acceleration, heel angle, pitch angle) and wave parameters. This substitution enables precise determination of resonance range based on actual dynamic conditions rather than static ship characteristics, achieving high measurement precision while maintaining automated implementation through electronic sensors and processors.
Solution Approach 2:
The system uses the watercraft's own motion sensors and onboard computers to automatically determine resonance range based on its actual motion state. The watercraft essentially measures and analyzes its own dynamics, eliminating the need for external estimation methods while maintaining implementation simplicity through automated self-monitoring and self-diagnosis capabilities.
Data Source
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AI summary
The method involves determining a vertical movement frequency range for a movement condition (x) of a water vehicle by determining a resonance frequency of vertical movement of the water vehicle, and partially determining whether the movement condition lies in the frequency range during driving of the water vehicle. A driving speed of the water vehicle and/or a route is changed by actuators till the frequency range drops, when the operating condition lies within the frequency range, where the actuators are controlled by actuator-controllers (7-9). An independent claim is also included for a device for executing a method for reducing vertical movement of a water vehicle.