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 stopping movement in the bow direction due to inertia forces, leading to significant deviations from target positions during dynamic positioning control.
Innovation Solution
A marine propulsion control system with a controller and memory that performs deceleration control to reduce bow direction speed, ensuring the vessel remains close to the target position by adjusting thrust and acting direction of outboard motors, and preventing deviations from predetermined routes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic positioning control is started before the vessel's bow direction movement stops, then the control system can begin positioning, but the vessel departs significantly from the target position due to inertia forces
Solution Approach 1:
The control system performs preliminary deceleration control before dynamic positioning control is fully activated. When the operation unit is operated, the controller first reduces the bow direction speed using deceleration control, and only after the speed is reduced does it activate the full dynamic positioning control, ensuring the vessel is close to the target position before positioning begins
Solution Approach 2:
The control system applies preliminary counter-action to the inertia forces by generating thrust in the stern direction before dynamic positioning control starts. This preliminary anti-action reduces the bow direction speed and prevents significant departure from the target position when positioning control is activated
2Ease of operation
If reduced thrust is used during dynamic positioning control to minimize sudden movement, then passenger comfort is improved, but the vessel takes too long to stop bow direction movement
Solution Approach 1:
The control system uses periodic or staged thrust application. First, deceleration control is applied to reduce bow direction speed, then dynamic positioning control with reduced thrust is applied to maintain position. This staged approach allows faster speed reduction initially, then maintains comfort during the positioning phase
3Quantity of substance
If the vessel is large with large inertia forces, then the vessel can carry more passengers and cargo, but it takes longer to stop bow direction movement during dynamic positioning control
Solution Approach 1:
For large vessels with significant inertia, the control system performs preliminary deceleration control before dynamic positioning control. This preliminary action reduces the bow direction speed using available thrust, and only after speed reduction does it activate the positioning control, ensuring larger vessels can also achieve accurate positioning without excessive time loss
Data Source
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 in which the marine vessel has changed to a mode in which the marine vessel is kept at a certain location, perform deceleration control to reduce a bow direction speed of the marine vessel. Alternatively, the controller is configured or programmed to, in a case in which 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 to prevent the marine vessel from moving in the bow direction.