Watercraft Steering Reaction Actuator Torque Control
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Solution Overview
Problem
Conventional watercraft steering systems with electric actuators face responsiveness issues and poor operation feel, especially when higher deflection torque is required, due to motor limitations and temperature-dependent motor characteristics, leading to impaired responsiveness and a less-than-ideal operation experience.
Innovation Solution
A steering system that includes a watercraft propulsion unit, an electric actuator, a reaction actuator, and a controller with status detection devices to compute and apply a torque target value, ensuring improved responsiveness and operation feel by adjusting the reaction force based on operation status, running status, and electric actuator status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a larger deflection torque is required for steering (faster steering wheel operation), then the steering motor becomes less responsive, resulting in poor operation feel
Solution Approach 1:
A reaction actuator is introduced as an intermediary device between the operator and the steering system. This reaction actuator generates a reaction force that is applied to the steering wheel, effectively mediating the interaction between the operator's steering input and the electric actuator's response. By controlling the reaction force, the system can compensate for the electric actuator's reduced responsiveness under high torque conditions, maintaining good operation feel across the full range of steering demands
2Temperature
If the temperature becomes higher, then the motor characteristics change providing lower torque, resulting in impaired responsiveness and poorer operation feel
Solution Approach 1:
The system incorporates temperature detection means to continuously monitor the electric actuator's temperature and feed this information back to the control unit. The control unit uses this feedback to dynamically adjust the reaction force generated by the reaction actuator, compensating for the torque reduction that occurs at higher temperatures. This feedback mechanism ensures that the steering responsiveness and operation feel are maintained despite temperature-induced motor characteristic changes
3Ease of operation
If a reaction torque is applied to the steering wheel based on external force, then the operator can feel external forces and respond quickly, but the steering motor becomes less responsive when larger output is required
Solution Approach 1:
The reaction force generated by the reaction actuator is made dynamic rather than fixed. The control unit continuously adjusts the reaction force based on real-time detection of steering wheel operation status, watercraft running status, and electric actuator status. This dynamic adjustment allows the system to provide appropriate reaction torque for feeling external forces during normal operation while ensuring sufficient steering responsiveness when larger output is required
Data Source
AI summary
A steering wheel, operable by an operator, can be electrically connected to an electric motor to provide an actuation signal corresponding to the amount of a steering wheel operation to the electric motor, a reaction motor for applying a reaction to the steering wheel, and an ECU for controlling the electric motor are provided. The ECU can include at least one of an operation status detection device for detecting an operation status corresponding to the steering wheel operation, a running status detection device for detecting a running status of the watercraft, an outboard motor status recognition device for recognizing a status of the outboard motor, such as the installation number thereof, and an electric motor status detection device for detecting a status of the electric motor. The ECU can also include a torque computation device for making a torque target value larger depending on the detection value from the at least one device, and a reaction motor control device for controlling the reaction motor in accordance with the torque target value computed by the torque computation device.