Watercraft Steering Control With DC Motor Overcurrent Limiting
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Solution Overview
Problem
Existing watercraft maneuvering systems lack an effective steering control system suitable for watercraft, as they rely on expensive motor technologies that are difficult to control directly due to varying motor currents, leading to potential overcurrent states and instability.
Innovation Solution
A watercraft maneuvering system utilizing a DC motor with a steering controller that performs voltage control and voltage limiting operations based on motor current feedback, preventing overcurrent states and ensuring stable steering through PWM control and duty ratio limitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a DC motor is used for steering actuation, then the cost of the steering actuator is reduced, but the motor current varies depending on load torque making direct current control impossible and risking overcurrent states
Solution Approach 1:
The steering controller performs feedback control by detecting the steering angle with a steering angle sensor and controlling the DC motor based on the detected angle and a target steering angle. Additionally, the controller detects motor current and performs voltage limiting control when the current exceeds a threshold or its increase rate is too high, ensuring stable operation despite load variations
Solution Approach 2:
The steering controller dynamically adjusts the voltage applied to the DC motor based on motor current conditions. When overcurrent is detected (current exceeding threshold or excessive increase rate), the controller limits the voltage to prevent damage, and otherwise applies voltage for proper steering control
2Ease of operation
If voltage control operation is performed to feedback-control the DC motor, then the steering angle can be controlled, but overcurrent states may occur due to varying load torque
Solution Approach 1:
The system implements dual feedback loops: one for steering angle control (comparing target steering angle with detected steering angle to control motor position) and another for current protection (detecting motor current and triggering voltage limiting when thresholds are exceeded)
Solution Approach 2:
The steering controller proactively prevents overcurrent by detecting motor current before damage occurs and limiting voltage when current exceeds safe thresholds or increases too rapidly, thereby preventing harmful effects before they manifest
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 system enables cost-effective and stable steering control of watercraft by using a DC motor, reducing the risk of overcurrent and maintaining efficient operation, even under varying load conditions.
Implementation Method 1
a steering actuator including a DC motor (Direct Current motor) and operable to change a steering angle
Implementation Method 2
a steering angle sensor to detect the steering angle
Implementation Method 3
to perform a voltage limiting control operation to limit the voltage to be applied to the DC motor based on a motor current flowing through the DC motor
Data Source
AI summary
A watercraft maneuvering system includes a steering including a steering actuator including a DC motor and operable to change a steering angle to change a course of a watercraft, a steering angle sensor to detect the steering angle, and a steering controller configured or programmed to drive the steering actuator by feedback-controlling the DC motor based on a target steering angle and an output signal of the steering angle sensor. The steering controller is configured or programmed to perform a voltage control operation to control a voltage to be applied to the DC motor, and perform a voltage limiting control operation to limit the voltage to be applied to the DC motor based on a motor current flowing through the DC motor.