Marine Engine Speed Control via Feed Forward Throttle Prediction
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Solution Overview
Problem
Existing marine propulsion systems face challenges in smoothly transitioning engine speed without overshoot or instability, particularly when changing from one selected engine speed to another, due to the need for high amplification gain in feedback controllers, which increases oscillation and instability.
Innovation Solution
The system predicts the throttle valve position needed to achieve the desired engine speed setpoint using a feed forward signal, bypassing the feedback controller, and then adjusts with a feedback controller to maintain the setpoint, reducing the amplification gain required and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high amplification gain is used in the feedback controller to achieve smooth engine speed transitions, then the response speed improves, but oscillation and instability increase
Solution Approach 1:
The feed forward signal calculates and applies the required throttle valve position adjustment in advance based on the engine speed setpoint change, before the feedback controller responds. This preliminary action eliminates the need for high amplification gain, allowing smooth transitions without oscillation or instability.
2Device complexity
If the feedback controller is used alone to adjust engine speed, then system simplicity is maintained, but overshoot and instability occur during speed transitions
Solution Approach 1:
The control system is segmented into two independent components: a feed forward signal path that calculates the required throttle adjustment based on setpoint changes, and a feedback controller path that maintains steady-state accuracy. This segmentation allows the feed forward signal to prevent overshoot and instability while the feedback controller ensures long-term accuracy, improving reliability without excessive complexity.
3Productivity
If the throttle valve is adjusted rapidly to achieve the setpoint speed, then productivity improves, but overshoot and instability increase
Solution Approach 1:
The feed forward signal performs preliminary calculation of the exact throttle valve position needed to achieve the desired engine speed setpoint. By applying this pre-calculated position command, the system can transition rapidly to the target speed without overshoot or instability, as the throttle is moved directly to the correct position rather than being aggressively adjusted from a distant starting point.
Data Source
AI summary
A method for setting an engine speed of an internal combustion engine in a marine propulsion device of a marine propulsion system to an engine speed setpoint includes determining the engine speed setpoint based on an operator demand and predicting a position of a throttle valve that is needed to achieve the engine speed setpoint. The method also includes determining a feed forward signal that will move the throttle valve to the predicted position, and after moving the throttle valve to the predicted position, adjusting the engine speed with a feedback controller so as to obtain the engine speed setpoint. An operating state of the marine propulsion system is also determined. Depending on the operating state, the method may include determining limits on an authority of the feedback controller to adjust the engine speed and/or determining whether the operator demand should be modified prior to determining the engine speed setpoint.