Watercraft Steering System Dynamic Torque Feedback Control
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Solution Overview
Problem
Conventional watercraft steering devices experience poor responsiveness and operation feel during rudder deflection, especially when higher torque is required, due to limitations in motor responsiveness and changing motor characteristics with temperature and watercraft conditions.
Innovation Solution
A steering system with a control unit that detects operation, running, and actuator status to compute and apply a reaction force to the steering wheel, adjusting torque based on detected values to maintain optimal responsiveness and feel, including sensors for rudder deflection force, load, speed, and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the steering wheel is operated faster requiring larger rudder deflection torque, then the responsiveness of the electric actuator decreases, but the operation feel becomes poorer
Solution Approach 1:
The reaction force applied to the steering wheel is made dynamic rather than fixed. The control unit adjusts the reaction force magnitude based on detected operating conditions (steering angle, steering speed, watercraft speed) to optimize both responsiveness and operation feel across different operating ranges. This allows the system to adapt to varying torque requirements during fast steering operations.
Solution Approach 2:
The system changes the parameter of reaction force magnitude based on detected operating conditions. By computing appropriate reaction forces from multiple parameters (steering angle, steering speed, watercraft speed) and adjusting the reaction actuator output accordingly, the system maintains optimal operation feel and responsiveness under varying load conditions.
2Temperature
If the motor characteristics change with temperature, then the torque output decreases, but the rudder deflection force becomes insufficient
Solution Approach 1:
The system implements feedback by detecting the watercraft's running status (including temperature conditions) and using this information to adjust the reaction force applied to the steering wheel. This feedback mechanism allows the system to compensate for motor characteristic changes due to temperature, ensuring sufficient rudder deflection force is maintained across varying thermal conditions.
Solution Approach 2:
The control unit computes and applies appropriate reaction forces in advance based on detected running status before the actual steering operation occurs. This preliminary adjustment of reaction force ensures that the motor operates within its capability range even before temperature-induced torque reduction fully manifests, maintaining rudder deflection performance.
3Force
If a reaction torque is applied to the steering wheel based on external force, then the operator can feel external force, but the operation feel becomes lighter when under no external force
Solution Approach 1:
The reaction force magnitude is made dynamic and adaptive rather than fixed. The control unit continuously adjusts the reaction force based on detected operating conditions including steering angle and steering speed. This dynamic adjustment ensures appropriate force feedback during external force conditions while maintaining light and easy operation during normal steering, resolving the contradiction between force feedback and ease of operation.
Data Source
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AI summary
The present invention relates to a steering system for a watercraft, comprising: a rudder, in particular an outboard motor (12); a steering device (16) including an actuator, in particular an electric motor (20) configured to change a direction in which the watercraft travels; a steering amount input means, such as a steering wheel (17), operable by an operator, electrically connected to the actuator (20) to provide an actuation signal corresponding to the amount of a steering operation to the actuator (20); a reaction actuator, such as a reaction motor (29) for applying a reaction force to the steering amount input device (17); and control means (33) for controlling the reaction actuator (29), the control means (33) including: at least one of operation status detection means (38) for detecting an operation status corresponding to the steering operation, running status detection means (39) for detecting a running status of the watercraft, watercraft propulsion unit status recognition means (40) for recognizing a status of a watercraft propulsion unit, in particular of an outboard motor (12), such as the installation number thereof, and actuator status detection means (41) for detecting a status of the actuator (20); torque computation means (42) for computing a torque target value based on the detection value from the at least one of the detection and recognition means; and reaction actuator control means (43) for controlling the reaction actuator (29) in accordance with the torque target value.