Marine Engine Speed Control via Feed Forward Throttle Prediction
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Solution Overview
Problem
Marine propulsion systems face instability and overshoot when changing engine speed due to the need for high amplification gain in feedback controllers, which compromises stability and response time.
Innovation Solution
Implementing a feed forward signal to predict and move the throttle valve to the desired position, reducing the reliance on feedback controllers for large changes, and adapting this signal based on operator-selected control modes and external conditions to enhance accuracy and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If feedback controller amplification gain is increased to reduce overshoot and improve stability, then system stability is improved, but response time deteriorates and the system becomes more sensitive to disturbances
Solution Approach 1:
The feed forward controller performs preliminary action by predicting the required throttle position before the feedback controller can respond to speed changes. This prediction is based on the desired engine speed and current operating conditions, allowing the throttle to be adjusted in advance rather than waiting for feedback from speed sensors, thereby improving response time while maintaining stability.
Solution Approach 2:
The feed forward controller acts as an intermediary between the desired engine speed and the throttle position. It processes the desired speed and operating conditions to calculate an intermediate throttle position that anticipates the required adjustment, reducing the burden on the feedback controller and improving overall system response without sacrificing stability.
2Measurement precision
If feedback controller amplification gain is increased to maintain engine speed accuracy, then speed control accuracy is improved, but system complexity and sensitivity to disturbances increase
Solution Approach 1:
The feed forward controller performs preliminary calculation of the required throttle position based on the desired engine speed and current operating conditions. This preliminary action reduces the workload on the feedback controller, allowing it to operate with lower amplification gain while maintaining speed accuracy, thereby reducing system complexity and sensitivity to disturbances.
3Speed
If throttle position is adjusted rapidly to respond to operator speed changes, then response speed is improved, but overshoot and instability increase
Solution Approach 1:
The feed forward controller performs preliminary action by calculating the required throttle position change in advance based on the desired engine speed and current conditions. This allows the throttle to be adjusted smoothly and predictably, preventing overshoot and instability while maintaining rapid response to operator inputs.
Solution Approach 2:
The feedback controller provides continuous feedback on actual engine speed to correct any deviations from the desired speed. This feedback mechanism works in conjunction with the feed forward controller to ensure stable operation, preventing overshoot while maintaining rapid response by adjusting the throttle position based on real-time speed measurements.
Data Source
AI summary
A method for setting an engine speed of an internal combustion engine in a marine propulsion system to an operator-selected engine speed includes predicting a position of a throttle valve of the engine that is needed to provide the operator-selected engine speed, and determining a feed forward signal that will move the throttle valve to the predicted position. After moving the throttle valve to the predicted position, the method next includes controlling the engine speed with a feedback controller so as to obtain the operator-selected engine speed. The feed forward signal is determined based on at least one of the following criteria: an operator-selected control mode of the marine propulsion system; and an external operating condition of the marine propulsion system. A system for setting the engine speed to the operator-selected engine speed is also described.