Marine Vessel Speed Control Phasing Derivative Term
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Solution Overview
Problem
Existing marine vessel propulsion systems face challenges in smoothly transitioning from acceleration to cruise control, often resulting in instability and overshoot due to the immediate introduction of a derivative term during mode transition, which can cause setpoint jumps and instability.
Innovation Solution
A method and system that phase in a derivative term of the feedback control algorithm only when the vessel speed is within a given range of the desired speed and the acceleration rate is less than a certain value, preventing step changes and reducing overshoot and undershoot by customizing control parameters for launch and cruise modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a derivative term is immediately introduced during mode transition from launch to cruise control, then the vessel speed control responds more quickly to speed deviations, but it causes setpoint jumps and instability
Solution Approach 1:
The patent applies preliminary action by pre-defining different derivative term gain values for different operating modes (launch vs. cruise). Before mode transition occurs, the system prepares the appropriate gain value, and upon transition, switches to the pre-prepared gain, avoiding sudden unstable changes while maintaining responsive control.
Solution Approach 2:
The patent implements dynamics by making the derivative term gain variable rather than fixed. The gain dynamically adapts based on the operating mode (launch or cruise), allowing the control system to optimize its response characteristics for each mode while maintaining stability during transitions.
2Device complexity
If a single feedback control algorithm is used for both launch and cruise modes, then the control system is simpler, but it results in overshoot and instability during mode transition
Solution Approach 1:
The patent applies segmentation by dividing the control algorithm into distinct segments for different operating modes. Each mode (launch, cruise, transition) has its own optimized feedback control parameters, allowing precise control for each operational phase while maintaining overall system reliability.
Solution Approach 2:
The patent implements parameter changes by adjusting feedback control parameters (particularly derivative term gain) based on the operating mode. This allows the same basic control algorithm structure to adapt its parameters for optimal performance in different modes, improving reliability without requiring completely different algorithms.
3Productivity
If the derivative term gain is kept high during mode transition, then the control system corrects speed deviations more aggressively, but it causes overshoot and oscillation
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the derivative term gain based on the operating mode. During launch mode, a higher gain enables aggressive correction, while during cruise mode, a lower gain prevents overshoot, and during transition, the gain is smoothly adjusted to maintain both correction efficiency and stability.
Data Source
AI summary
A method for controlling a speed of a marine vessel includes accelerating the marine vessel in response to a launch command. The method then includes holding the vessel speed at a desired vessel speed with a controller using feedback control. The controller phases in a derivative term of the feedback control in response to determining that the following conditions are true: (a) the vessel speed is within a given range of the desired vessel speed; and (b) an acceleration rate of the marine vessel is less than a given value.