Boat Propulsion System Lateral Movement Control
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Solution Overview
Problem
Existing boat propulsion systems with four units face challenges in lateral movement due to limited steerage of outside units and insufficient propulsion force when trying to move laterally, as the lines of action of propulsion forces do not always align with the resistance center, and steering only the inside units results in inadequate propulsion force for larger boats.
Innovation Solution
A boat propulsion system with four independently controllable units, where the first and second port-side units and first and second starboard-side units generate resultant forces that balance to position their points of action behind and in front of the resistance center, allowing lateral movement while reducing steer angle and increasing propulsion force by coordinating the forward, reverse, and steer angles of all units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the outside propulsion units are steered to align their lines of action with the resistance center for lateral movement, then the lateral movement capability is improved, but the steer angle limitation prevents sufficient steerage and reduces propulsion force
Solution Approach 1:
The four propulsion units are divided into inside units (first and second port-side units) and outside units (first and second starboard-side units), with different control strategies applied to each group. The inside units are steered to align lines of action with the resistance center, while the outside units are controlled to generate resultant forces at specific points, allowing each segment to optimize its contribution to lateral movement
Solution Approach 2:
The control unit dynamically adjusts multiple parameters including steer angles and propulsion forces of all four units based on operational commands. By changing these parameters in coordination, the system achieves effective lateral movement despite the steer angle limitations of individual outside propulsion units
2Ease of operation
If only the inside propulsion units are steered for lateral movement, then the steerage is sufficient, but the propulsion force becomes insufficient for larger boats
Solution Approach 1:
The control unit merges the contributions of all four propulsion units by coordinating their steer angles and propulsion forces. The inside units provide steerage while the outside units contribute additional propulsion force, and their combined resultant forces achieve both sufficient steerage and propulsion force for lateral movement of larger boats
3Speed
If the lines of action of all propulsion units are aligned with the resistance center, then lateral movement is achieved, but the steer angle limitation of outside units prevents proper alignment
Solution Approach 1:
Different control strategies are applied asymmetrically to inside and outside propulsion units. The inside units are controlled for precise line of action alignment with the resistance center, while the outside units are controlled to generate resultant forces at specific points behind the resistance center, creating an asymmetric control approach that overcomes the steer angle limitation
4Force
If the propulsion force is increased to compensate for inadequate steerage, then the propulsion force is sufficient, but the steer angle limitation remains and causes inefficiency
Solution Approach 1:
The control unit continuously monitors and adjusts the steer angles and propulsion forces of all four units based on operational commands and system performance. This feedback control ensures that propulsion force is optimized while maintaining effective steerage, improving overall propulsion efficiency by coordinating all units rather than simply increasing force to compensate for poor steerage
Data Source
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AI summary
[Problem] An object of the present invention is to provide a boat propulsion system and a method for controlling a boat propulsion unit in which a boat can be effectively made to move laterally on the basis of an operational command provided by an operation portion in a boat equipped with at least four propulsion units. [Solution] A control unit individually controls the forward and reverse propulsion directions, the propulsion force, and the steer angle of the plurality of boat propulsion units so that a point of action of a first resultant force is positioned behind a point of action of a second resultant force when the control unit receives a operational command for operation in the lateral direction from the operation portion. The first resultant force is the resultant force of propulsion force generated by the first port-side propulsion unit and the first starboard-side propulsion unit. The second resultant force is the resultant force of propulsion force generated by the second port-side propulsion unit and the second starboard-side propulsion unit.