Watercraft Steering Device Dynamic Torque Control
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Solution Overview
Problem
Conventional watercraft steering systems with electric actuators face responsiveness issues when a larger deflection torque is required, particularly at higher speeds or temperatures, leading to a poor operation feel due to motor limitations and changing torque characteristics.
Innovation Solution
A watercraft steering device that includes a propulsion unit, a steering device actuated by an electric actuator, and various detection and control means to compute lower unit turning force characteristics and control reaction forces, propulsive forces, and select the electric actuator operation, ensuring improved responsiveness and operation feel by adjusting reaction forces and turning angles based on detected status values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a larger deflection torque is required for steering at higher operation speeds, then the steering motor output must be increased, but the motor becomes less responsive and operation feel deteriorates due to exceeding motor limits
Solution Approach 1:
The patent applies dynamics by making the lower unit turning angle limit variable rather than fixed. The control unit dynamically adjusts the lower unit turning angle limit based on detected watercraft speed and steering wheel operation amount. At higher speeds, the system restricts the lower unit turning angle to prevent the steering motor from exceeding its output limits, thereby maintaining responsiveness and preventing motor damage while still allowing adequate steering capability when needed.
Solution Approach 2:
The patent changes the parameter of lower unit turning angle limit based on operating conditions. The control unit modifies this parameter according to watercraft speed and steering operation amount, ensuring the steering motor operates within its optimal performance range across different speed conditions, thus maintaining responsiveness without requiring increased motor output.
2Ease of operation
If the lower unit turning angle limit is increased to improve steering capability, then steering performance improves, but the steering motor may exceed its output limit causing impaired responsiveness
Solution Approach 1:
The system dynamically adjusts the lower unit turning angle limit based on real-time detection of watercraft speed and steering wheel operation. This dynamic adjustment ensures steering capability is maintained within safe motor output limits across varying operating conditions, preventing motor overload while providing adequate steering authority when needed.
Solution Approach 2:
The control unit uses feedback from speed detection means and steering wheel operation detection to continuously monitor system state and adjust the lower unit turning angle limit accordingly. This closed-loop control ensures the motor operates within its output capabilities while maintaining effective steering performance.
3Ease of operation
If reaction force to the steering wheel is increased to improve operator feel, then operator control is enhanced, but the steering motor requires higher output reducing responsiveness
Solution Approach 1:
The system dynamically controls reaction force characteristics through variable lower unit turning angle limits. By adjusting this limit based on speed and steering operation, the system provides appropriate reaction forces to the steering wheel for operator feedback while preventing the steering motor from operating beyond its responsive range, thus maintaining both operation feel and responsiveness.
Data Source
AI summary
A watercraft steering device can include at least one of steerage status detection device configured to detect a steerage status following an operation of the steering wheel, running status detecting device configured to detect a running status of the watercraft, watercraft propulsion unit status recognition device configured to recognize a status of an outboard motor such as an installation number thereof, and electric motor status detection device configured to detect a status of an electric motor, and can further include a lower unit turning force characteristic computation device configured to compute a lower unit turning force characteristic based on a detection value from at least one of the device, and an ECU configured to control at least one of a reaction force to the steering wheel, a limit lower unit turning angle, and a propulsive force based on a computed lower unit turning force characteristic and/or selecting the electric actuator to operate.