Vessel Steering System Dynamic Propulsion Limit Control
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Solution Overview
Problem
Existing vessel steering systems face challenges in finely adjusting the position of a vessel in fixed point holding mode due to difficulties in determining an appropriate propulsive force, which is affected by weather conditions and vessel type, making it hard to counter disturbances like wind or water flow.
Innovation Solution
A vessel steering system that includes a controller which acquires vessel position or speed parameters, determines a target value, and adjusts the propulsion device's output within a predetermined upper limit value through feedback control, increasing the limit when the demand output exceeds a threshold to ensure appropriate propulsive force for maintaining the target position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the propulsive force is increased to counter disturbances like wind or water flow, then the vessel can be held at the target position, but it becomes difficult to finely adjust the position of the vessel
Solution Approach 1:
The patent applies dynamics by making the upper limit value of propulsive force adjustable rather than fixed. The controller dynamically changes the upper limit value based on the demand output from feedback control, allowing the system to adapt between requiring strong propulsive force to counter disturbances and requiring fine position adjustment, thereby resolving the contradiction between reliability and manufacturing precision
Solution Approach 2:
The patent changes the parameter of upper limit value for propulsive force based on operating conditions. When the demand output exceeds a threshold, the upper limit value is increased to provide sufficient propulsive force for counteracting disturbances; when the demand output is within the threshold, the upper limit value is maintained at a lower level to enable fine position adjustment, thus resolving the contradiction through parameter adaptation
2Manufacturing precision
If the propulsive force is decreased to enable fine position adjustment, then the vessel position can be precisely controlled, but it becomes difficult to counter disturbances like wind or water flow
Solution Approach 1:
The system dynamically adjusts the upper limit value of propulsive force based on real-time feedback. When disturbances are detected and the demand output exceeds the threshold, the upper limit value is increased to provide sufficient force for counteracting disturbances, while maintaining fine position adjustment capability when conditions allow, thereby resolving the contradiction between precision and reliability
Solution Approach 2:
The controller changes the upper limit value parameter according to the demand output from feedback control. When the demand output is within the threshold, a lower upper limit value enables precise position control; when the demand output exceeds the threshold, the upper limit value is increased to ensure sufficient propulsive force for counteracting disturbances, thus resolving the contradiction through adaptive parameter changes
3Device complexity
If a fixed upper limit value is used for propulsive force, then the control system is simple, but it is difficult to determine an appropriate propulsive force that works for all conditions such as weather or vessel type
Solution Approach 1:
The patent implements feedback control where the controller continuously monitors the demand output (deviation between actual and target position) and adjusts the upper limit value of propulsive force accordingly. This feedback mechanism enables the system to adapt to different conditions such as weather and vessel type without requiring complex pre-programming, resolving the contradiction between device complexity and adaptability by using a relatively simple feedback loop
Solution Approach 2:
The system performs self-adjustment by automatically modifying the upper limit value based on the demand output from feedback control. The controller itself determines the appropriate propulsive force for current conditions without external intervention, enabling the system to adapt to various conditions while maintaining simple control logic, thus resolving the contradiction between device complexity and adaptability
Data Source
AI summary
A propulsive force suitable to hold a vessel at a target position is determined, by a controller that controls a propulsion device in a fixed point holding mode to hold the position of the vessel. The controller acquires a parameter including the position of the vessel or a vessel speed. The controller determines a target value for the parameter. The controller determines a demand output of the propulsion device within a predetermined upper limit value or less by feedback control according to a deviation between the parameter and the target value. The controller increases the upper limit value when the demand output of the propulsion device is greater than or equal to a first threshold. The first threshold is defined by a predetermined ratio with respect to the upper limit value.