Ship Propulsion Control for Lateral Motion Without Hull Turning
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Solution Overview
Problem
In ships with propulsion devices disposed on the rear portion of the hull, the front portion starts moving later than the rear portion when the joystick is tilted, causing the ship to turn counterclockwise, which is undesirable.
Innovation Solution
The ship propulsion device controller generates an initial rotating moment in a specific direction followed by a propulsion force without generating the rotating moment during a subsequent period to prevent the front portion from starting its movement later than the rear portion, thereby preventing the ship from turning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the ship propulsion device generates only a rightward propulsion force when the joystick is tilted to the right, then the ship can move to the right, but the front portion of the hull starts moving later than the rear portion, causing the ship to turn counterclockwise
Solution Approach 1:
The control device applies a preliminary rotating moment in the clockwise direction before the intended rightward movement. This preliminary action generates initial rotational momentum that ensures the front portion of the hull starts moving simultaneously with or before the rear portion, preventing the unwanted counterclockwise turning that would otherwise occur during the transition from neutral to tilted joystick position
Solution Approach 2:
The control device generates a rotating moment in the opposite direction (clockwise) to counteract the inherent tendency of the hull to turn counterclockwise when the front portion starts moving later. This preliminary anti-action compensates for the delayed response of the front portion, ensuring the hull maintains its attitude during the maneuver
2Stability of the object's composition
If the ship propulsion device generates a rotating moment continuously, then the hull attitude can be controlled, but the ship will continue to rotate even after the desired movement is achieved
Solution Approach 1:
The control device applies the rotating moment only during a specific time period from the first timing when the operation unit is moved to the second timing. After this period expires, the rotating moment is stopped while the propulsion force continues. This periodic application ensures the hull achieves the desired attitude without continuous rotation, eliminating the harmful effect of unwanted ongoing rotation
Solution Approach 2:
The rotating moment is applied only during the initial phase of the maneuver to establish the correct hull attitude. Once the attitude is established, the rotating moment is discontinued, allowing the propulsion force alone to maintain the movement without causing additional rotation
Data Source
Figure 1
Figure 2
Figure 3(A)~3(I)
AI summary
A ship propulsion device controller controls a plurality of ship propulsion devices disposed on a rear portion of a hull of a ship. The ship includes an operation unit configured to operate the ship propulsion devices. The operation unit is able to be positioned at a first position where the ship propulsion devices do not generate propulsion forces for the ship and a second position where the ship propulsion devices generate propulsion forces for moving the ship in a right direction, a right-forward direction, or a right-backward direction or a third position where the ship propulsion devices generate a propulsion force for moving the ship in a left direction, a left-forward direction, or a left-backward direction. When the operation unit is moved from the first position to the second position and maintained at the second position, the ship propulsion devices generate a clockwise rotating moment in the ship during a first period from a first timing when the operation unit is moved to the second position to a second timing and do not to generate the clockwise rotating moment in the ship during a second period after the second timing.