Dynamic Positioning Control for Vessel Drive-Off Prevention
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Solution Overview
Problem
Dynamic positioning systems in offshore vessels face issues with 'drive-off' due to errors in position determination sensors, leading to unnecessary vessel movements and potential damage to infrastructure like risers, especially when there are sudden increases in power demand without corresponding changes in weather or environmental conditions.
Innovation Solution
A drive-off prevention controller that monitors weather and environmental data, adjusts the propulsion system by limiting power characteristics based on indicative conditions such as stable weather conditions, riser properties, and position discrepancies, to prevent incorrect vessel movements and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the propulsion system responds to sudden power demand increases, then position corrections can be made quickly, but unnecessary movements may occur during stable weather conditions
Solution Approach 1:
The control system dynamically adjusts its response characteristics based on real-time weather conditions and power demand rates. During stable weather conditions, the system applies dynamic limiting to sudden power demand increases, while during changing weather conditions, it allows faster responses. This dynamic adaptation resolves the contradiction between quick position correction and position stability
2Reliability
If the drive-off prevention controller limits power increases during stable conditions, then unnecessary vessel movements are prevented, but operator intervention time is required
Solution Approach 1:
The system performs preliminary actions by pre-establishing weather condition thresholds and power demand rate limits. When stable weather conditions are detected, the system proactively configures limiting parameters before drive-off can occur. This preliminary configuration reduces the need for urgent operator intervention while maintaining reliable drive-off prevention
Solution Approach 2:
The control system provides self-service by automatically monitoring weather conditions, calculating power demand rates, and adjusting propulsion limits without requiring continuous operator attention. The system serves itself by detecting when limiting is needed and automatically applying the appropriate control actions, reducing operator intervention time while maintaining reliable drive-off prevention
Data Source
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AI summary
A drive-off prevention controller for a dynamic positioning system, the drive off prevention controller being configured to communicate with the dynamic positioning system, wherein the dynamic positioning system is configured to determine a position of a vessel relative to a target position and to control a propulsion system of the vessel based on the determined position of the vessel relative to the target position; and the drive-off prevention controller is configured to, based on one or more indicative conditions, selectively adjust the control of the propulsion system determined by the dynamic positioning system or that would otherwise have been determined by the dynamic positioning system; and at least one of the indicative conditions comprises the demand, or rate of increase in demand, of the propulsion system being greater than a first conditional threshold whilst weather or environmental data received by the drive-off prevention controller indicates that there has been no corresponding change in weather or environmental conditions.