Ship Speed Control During Turning to Reduce Engine Load Fluctuation
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Solution Overview
Problem
Existing ship control systems experience unnecessary load fluctuations on the main engine during turning, leading to increased fuel consumption due to interference between ship speed control and rudder angle control.
Innovation Solution
A ship control system that includes a main engine controller for feedback control of actual ship speed, a turning judgment unit to determine if the ship will turn, and a control change unit that lowers the responsiveness of ship speed control when turning is judged, thereby reducing load fluctuations by maintaining or reducing the main engine's rotational frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the main engine torque is increased during ship speed control upon detection of rudder operation or yaw rate, then the turning speed is improved, but unnecessary load fluctuations occur on the main engine leading to increased fuel consumption
Solution Approach 1:
The control change unit performs lowering processing in advance when the turning judgment unit predicts that the ship will turn, before the actual rudder operation occurs. This preliminary action prevents the interference between speed control and rudder control from happening in the first place, thereby avoiding unnecessary load fluctuations and fuel consumption while still maintaining adequate turning performance.
2Measurement precision
If the responsiveness of ship speed control is maintained at normal levels during turning, then the ship speed control precision is improved, but load fluctuations on the main engine increase due to interference with rudder angle control
Solution Approach 1:
The system dynamically adjusts the responsiveness of ship speed control based on the turning state. When the turning judgment unit determines the ship will turn, the control change unit lowers the responsiveness by increasing the determination threshold or extending the determination period. This dynamic adjustment prevents harmful load fluctuations during turning while restoring normal responsiveness when turning is complete, thus eliminating the need to choose between precision and stability.
3Speed
If the ship speed control and rudder angle control both operate at full responsiveness during turning, then the control responsiveness is improved, but the interference between controls causes unnecessary load fluctuations on the main engine
Solution Approach 1:
The invention extracts and separates the speed control responsiveness from the turning state. When turning is detected, the system selectively reduces only the speed control responsiveness while leaving the rudder angle control unaffected. This separation allows the rudder control to maintain full responsiveness for effective turning, while the speed control becomes less aggressive, thereby eliminating the interference that causes load fluctuations without compromising overall control effectiveness.
Data Source
AI summary
In a ship control system of one embodiment, a main engine controller performs, when controlling the rotational frequency of a main engine based on a target ship speed of a ship, feedback control of an actual ship speed of the ship to perform ship speed control for bringing the actual ship speed closer to the target ship speed. A turning judgment unit judges whether or not the ship will turn. A control change unit performs, when the turning judgment unit has judged that the ship will turn, lowering processing for lowering the responsiveness of the ship speed control.