Ship Steering Device with Dynamic Ratio Map
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Solution Overview
Problem
Conventional ship steering devices with steer-by-wire technology do not adequately reduce ship handling effort, as they lack effective mechanisms to account for the differences in water repelling characteristics of outboard motor propellers, leading to inefficient steering and increased effort for operators.
Innovation Solution
A ship steering device that includes a handle mechanically separated from the rudder mechanism, a steering angle detecting unit, a reaction force motor, and a turn controller utilizing a steering characteristics map to control the rudder motor, optimizing the turn angle based on the steering angle, thereby reducing handling effort by associating steering angles with appropriate turn angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant steering ratio is used in steer-by-wire systems, then the mechanical structure is simple, but the ship handling effort is not adequately reduced due to water repelling characteristics differences
Solution Approach 1:
The patent implements dynamic steering ratios that vary based on steering angle regions. The first steering ratio applies when the steering angle is within a first range, and a second steering ratio applies when the steering angle exceeds this range. This dynamic adjustment optimizes ship handling effort across different operating conditions while accounting for water repelling characteristics differences of the propeller.
Solution Approach 2:
The system changes the steering ratio parameter based on the detected steering angle. When the steering angle detecting unit detects that the steering angle has exceeded the first range, the switching unit switches from the first steering ratio to the second steering ratio. This parameter change allows the system to adapt to different hydrodynamic conditions and reduce handling effort effectively.
2Ease of operation
If the handle is mechanically separated from the rudder mechanism, then steering effort is reduced, but the steering characteristics become less intuitive and require complex control algorithms
Solution Approach 1:
The patent employs parameter changes by switching between different steering ratios based on the steering angle. The control unit detects the steering angle and switches between a first steering ratio (when angle is within first range) and a second steering ratio (when angle exceeds first range). This approach maintains intuitive steering characteristics while enabling effective handling effort reduction through mechanical separation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces ship handling effort by providing a more responsive and efficient steering mechanism, improving controllability and stability while minimizing operator input, especially during slow-speed maneuvers and U-turns.
Implementation Method 1
a reaction force motor that generates reaction force torque to be applied to the handle
Implementation Method 2
a rudder motor that drives a rudder mechanism of the outboard motor
Data Source
AI summary
A ship steering device includes a handle which is mechanically separated from a rudder mechanism, a steering angle detecting unit that detects a steering angle of the handle, a rudder motor that drives the rudder mechanism, and a turn controller that controls, based on a steering characteristics map which associates a basic relation between the steering angle and a turn angle, the rudder motor so as to obtain the turn angle in accordance with the steering angle. The steering characteristics map has a characteristic such that, in a second steering region where the steering angle is larger than the steering angle in a first steering region, a change amount of the turn angle relative to the steering angle is large with respect to the first steering region where the steering angle is set from zero in advance.