Offshore Crane Target Tracking for Ship-to-Ship Load Slamming
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Solution Overview
Problem
Ship-to-Ship Transfer operations using cranes are hindered by 'load slamming' due to relative vessel movements, which are difficult to manage with existing methods, especially in unfavorable weather conditions, leading to safety risks and increased costs.
Innovation Solution
A target tracking device mounted on a crane, in conjunction with an optical target on a second vessel, enables real-time determination of relative motion between vessels, allowing for active heave compensation and precise adjustment of lifting capacity to mitigate 'load slamming' risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional derating charts are used to limit load capacity based on estimated wave heights, then safety against load slamming is improved, but operational productivity deteriorates due to conservative load limits and visual estimation inaccuracies
Solution Approach 1:
The patent replaces visual estimation methods and conventional derating charts with an automated optical target tracking system. The target tracking device optically measures relative motion between vessels in real-time, eliminating the need for manual wave height estimation and conservative derating practices. This substitution enables more accurate and dynamic load capacity determination, improving both safety and operational efficiency.
Solution Approach 2:
The system implements real-time feedback by continuously tracking the target on the second vessel and measuring relative motion parameters. This feedback loop provides up-to-date information about vessel relative positions and velocities, allowing dynamic adjustment of crane operations to maintain safety margins while maximizing operational capability under actual conditions.
2Reliability
If STS operations are limited to favorable weather conditions to reduce load slamming risks, then safety is improved, but operational time and productivity worsen due to vessel stand-by requirements
Solution Approach 1:
The patent transitions from static weather-based operational limits to dynamic real-time measurement and control. The target tracking system continuously monitors relative motion between vessels and provides real-time data for crane control adjustments, enabling safe operations under a broader range of weather conditions by adapting to actual conditions rather than relying on predetermined weather thresholds.
Solution Approach 2:
The system changes the operational parameters from fixed weather condition thresholds to dynamic real-time measurements of relative motion. By measuring actual relative positions and velocities of vessels moment-by-moment, the system enables operational decisions based on actual conditions rather than conservative pre-set limits, expanding the operational window.
3Speed
If wireless MRU sensors are used for active heave compensation, then real-time motion data acquisition is improved, but system reliability worsens due to wireless link interruptions
Solution Approach 1:
The patent introduces an optical target as an intermediary object placed on the second vessel. Instead of using wireless sensors on the vessel, the target tracking device on the first vessel optically tracks this physical target. This intermediary approach converts the measurement problem into an optical tracking problem, providing reliable real-time data without wireless communication vulnerabilities.
Solution Approach 2:
The system replaces wireless electronic sensing with optical tracking. The target tracking device uses optical methods to measure relative motion, substituting the wireless MRU sensor system with an optical measurement system that is not susceptible to wireless link interruptions while maintaining real-time measurement capability.
Data Source
AI summary
Aspects of the disclosure include apparatus for and methods of facilitating transfer of objects using a crane. Disclosed apparatuses include a target tracking device mounted on or near a crane at a first location, and a target located near a landing location for the object. The target tracking device and the target facilitate real time determination of relative motion between the two locations. Methods of using the same are also disclosed.