Capsize Risk Calculation via Oscillation Detection
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Solution Overview
Problem
Existing capsize risk calculation systems for vessels are ineffective when hull information is unclear or absent, particularly for small and medium-sized vessels, and even for large vessels, as hull information varies with environmental and operational conditions, making it difficult to accurately assess capsize risk without specific data.
Innovation Solution
A capsize risk level calculation system that uses up-down direction detection and rolling direction detection to calculate capsize risk based on oscillation radii and limit oscillation radii, without requiring hull information, employing sensors and a data processing apparatus to determine capsize limit inclination angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capsize risk calculation systems use hull information (ship width, center-of-gravity location, buoyancy center location, metacenter location) to determine capsize risk, then the capsize risk can be assessed based on design phase data, but the system becomes ineffective when hull information is unclear, absent, or has deviated from actual conditions due to modifications, reselling, or environmental variations
Solution Approach 1:
The patent replaces the conventional mechanical/naval architecture approach (using static hull information and geometric parameters) with a sensor-based dynamic measurement system. Acceleration sensors detect actual vessel oscillations in real-time, and the system calculates capsize risk based on measured motion characteristics rather than theoretical hull properties. This substitution enables capsize risk assessment for vessels regardless of whether accurate hull information is available.
Solution Approach 2:
The system enables vessels to self-assess their capsize risk by measuring their own oscillation characteristics through onboard acceleration sensors. The vessel's actual dynamic behavior is used to determine its stability characteristics, eliminating the need for external hull information or design data. The vessel essentially measures itself to determine its capsize risk level.
2Reliability
If the system relies on hull information that varies with peripheral environment (wind intensity, wave height, seawater density) and vessel conditions (cargoes, residual fuel), then design phase data may not reflect actual operating conditions, but collecting and processing this variable data in real-time increases system complexity
Solution Approach 1:
The patent extracts the essential stability information directly from the vessel's oscillation behavior rather than attempting to account for all environmental and operational variables. By measuring the actual oscillation period and damping characteristics, the system derives stability parameters that inherently reflect the combined effects of hull form, loading conditions, and environmental factors, eliminating the need to separately measure or model each variable.
Solution Approach 2:
The system transitions from static hull information to dynamic oscillation measurement. Instead of using fixed design-phase parameters that may not reflect current conditions, the system continuously measures the vessel's oscillation characteristics in real-time. These dynamic measurements automatically adapt to changing conditions such as loading, environmental factors, and hull modifications, providing always-current stability assessment.
3Adaptability or versatility
If small and medium-sized vessels are exempted from providing hull stability information by law, then these vessels (which account for most capsizing accidents) cannot use conventional capsize risk calculation systems, but requiring them to provide hull information creates administrative burden and may not ensure data accuracy
Solution Approach 1:
The patent replaces the administrative/legal requirement for hull information provision with a physical measurement system. Instead of requiring vessels to provide documentation or data about their hull characteristics, the system directly measures oscillation behavior using acceleration sensors. This approach works equally well for small and medium-sized vessels regardless of their legal exemption status, as it relies on physical measurement rather than documentary evidence.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the calculation of capsize risk levels for vessels without needing hull information, providing an index of capsizing risk through oscillation detection, thus improving safety by accounting for dynamic conditions.
Implementation Method 1
an up-down direction detection means for detecting a reciprocating motion in an up-down direction of a vessel as an oscillation in an up-down direction of a virtual oscillation center axis
Implementation Method 2
a rolling direction detection means for detecting a simple pendulum motion in a rolling direction around the center axis of the vessel as a simple pendulum motion of the center of gravity of the vessel around the oscillation center axis
Data Source
AI summary
Provided is a capsize risk level calculation system which can calculate a capsize risk level providing an index of the capsize risk on an oscillation of hull without using hull information. This system includes an acceleration sensor detecting a reciprocating motion in an up-down direction of a vessel as an oscillation in an up-down direction of a virtual oscillation center axis; an angular velocity sensor detecting a simple pendulum motion in a rolling direction around the vessel center axis as a simple pendulum motion of the vessel COG around the oscillation center axis; and an arithmetic part calculating a capsize risk level from an oscillation radius connecting between the oscillation center axis and the vessel COG, and a capsize limit oscillation radius connecting between the oscillation center axis and the vessel metacenter, which are obtained on the results of detection by the acceleration sensor and the angular velocity sensor.