Marine Propulsion Control for Bow-Speed Deceleration in Dynamic Positioning
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Solution Overview
Problem
Large marine vessels equipped with dynamic positioning control systems face challenges in smoothly stopping their bow direction movement due to high inertia forces, leading to significant deviations from target positions during dynamic positioning control.
Innovation Solution
A propulsion control system with a controller that gradually increases thrust for deceleration control, maintaining it at a predetermined value when necessary, to effectively reduce bow direction speed and prevent vessel deviation from target positions, while also guiding the vessel along predetermined routes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If reduced thrust is used in dynamic positioning control to curb sudden movement and avoid passenger discomfort, then passenger comfort is improved, but the vessel takes too long to stop bow direction movement and departs significantly from target position
Solution Approach 1:
The system dynamically adjusts thrust based on vessel speed conditions. When bow direction speed exceeds a predetermined threshold, the system switches to enhanced deceleration control with higher thrust values, and when speed is below the threshold, it uses normal dynamic positioning control with reduced thrust. This dynamic adaptation resolves the contradiction by applying different control strategies appropriate to different operational states.
Solution Approach 2:
The control system changes the thrust parameter based on vessel speed. By monitoring bow direction speed and comparing it to a threshold, the system adjusts the thrust magnitude - using larger thrust values for deceleration when speed is high, and reduced thrust values for positioning maintenance when speed is low. This parameter change enables the system to achieve both stopping accuracy and passenger comfort.
2Productivity
If dynamic positioning control is started before bow direction movement stops, then operational responsiveness is improved, but positioning accuracy deteriorates due to high inertia forces
Solution Approach 1:
The system performs preliminary deceleration action when it detects that dynamic positioning control is requested while bow direction speed is above the threshold. The enhanced deceleration control activates before the vessel reaches the target position, reducing speed to an appropriate level for accurate positioning. This preliminary action ensures that the vessel is ready for precise positioning control without sacrificing operational responsiveness.
Solution Approach 2:
The system continuously monitors bow direction speed and uses this feedback to determine whether to activate enhanced deceleration control. When the speed feedback exceeds the threshold, the system responds by applying larger thrust values for deceleration. This feedback mechanism enables the system to maintain positioning accuracy while responding quickly to positioning requests.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A propulsion control system for a marine vessel, includes a memory, and a controller coupled to the memory. The controller is configured or programmed to, while performing dynamic positioning control of the marine vessel or in a case where the marine vessel has changed to a mode in which the marine vessel is kept in a certain position, perform deceleration control that reduces a bow direction speed of the marine vessel. Alternatively, the controller is configured or programmed to, in a case where the marine vessel has changed to a mode in which the marine vessel moves along a predetermined route, when the marine vessel deviates from the predetermined route in a bow direction of the marine vessel, perform deceleration control that prevents the marine vessel from moving in the bow direction.