Marine Propulsion Speed Control via Rotational Correlation
Solution Overview
Problem
Existing marine vessel speed control methods face inaccuracies and inflexibility due to unreliable sensor data, particularly with speed-through-water transducers and GPS delays, leading to overshooting or undershooting target speeds during transitional phases.
Innovation Solution
A method that determines and stores constant vessel speed and rotational speed values to create a correlation record, allowing for precise control by correlating vessel speed with rotational speed, thereby adapting to individual vessel characteristics and reducing errors from sensor inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If speed-through-water transducer is used for speed control, then speed measurement is provided, but the data is unreliable leading to inaccurate speed control
Solution Approach 1:
The patent introduces an intermediary correlation model that maps between rotational speed (reliable measurement) and vessel speed (unreliable direct measurement). Instead of directly using unreliable transducer data, the system uses rotational speed as an intermediary variable that correlates with vessel speed through stored empirical relationships, thereby achieving accurate speed control without relying on unreliable transducer readings
Solution Approach 2:
The patent replaces the mechanical speed-through-water transducer system with an alternative measurement approach based on rotational speed sensing. By substituting the direct mechanical speed measurement method with rotational speed measurement combined with correlation-based estimation, the system achieves more reliable and accurate speed control
2Measurement precision
If GPS device is used for speed control, then speed-over-ground data is provided, but the delay makes it difficult to use in vessel transitional speed control
Solution Approach 1:
The patent performs preliminary action by storing correlation data between rotational speed and vessel speed during normal operation. This pre-established correlation model allows the control system to predict current vessel speed from current rotational speed without waiting for delayed GPS data, enabling real-time transitional speed control
Solution Approach 2:
The patent implements a feedback mechanism where rotational speed (measured in real-time) is continuously correlated with vessel speed through the stored model. This creates an immediate feedback loop that responds to current operating conditions without the time delays inherent in GPS-based systems, allowing for responsive transitional speed control
3Ease of operation
If predetermined acceleration profile is used for speed control, then engine speed can be controlled, but it provides unpractical vessel speed to time correlation for many vessel types
Solution Approach 1:
The patent makes the speed control system dynamic by storing multiple correlation data sets corresponding to different operating conditions, vessel types, and environmental factors. Instead of a fixed predetermined profile, the system dynamically selects and applies the appropriate correlation model based on current conditions, providing both simplicity and adaptability
Solution Approach 2:
The patent changes the controlling parameter from time-based predetermined profiles to condition-based correlation models. By storing and applying correlation data that reflects actual vessel characteristics and operating conditions rather than generic time profiles, the system adapts to different vessel types and situations while maintaining ease of operation
Data Source
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AI summary
A method for a propulsion arrangement (101) for providing propulsive power to a marine vessel (1), the method comprising the steps of: - determining (S1) whether the vessel (1) is running by means of the propulsion arrangement at a constant vessel speed, - storing (S3) a value (V1) of the constant vessel speed, - detecting (S4) a value (n1) of a rotational speed of a rotatable part (102) of the propulsion arrangement while the vessel is running at the constant vessel speed, - storing (S5) the detected rotational speed value, - subsequently controlling (S6) the propulsion arrangement so as to change the vessel speed, - subsequently repeating (S7-S11) the steps of determining whether the vessel is running at a constant vessel speed, storing a value (V2-V4) of the constant vessel speed, and detecting and storing a value (n2-n4) of the rotational speed of the rotatable part, to obtain a plurality of stored pairs of vessel speed values and rotational speed values, and - creating (S12) based at least partly on the stored pairs of values a correlation record (126) correlating vessel speed values with rotational speed values.