Ship Steering Control Using Intermediate Waypoints in Waves
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Solution Overview
Problem
Existing automatic steering systems for ships face challenges in accurately navigating along a desired route due to external factors like waves, which can cause deviations from the planned path after veering has started.
Innovation Solution
An automatic steering device comprising a route calculator, intermediate waypoint calculating module, command steering angle calculating module, and steering controlling module, which calculates and updates the command steering angle based on the positional relation between the route and intermediate waypoints, allowing for precise control of the ship's steering mechanism to maintain route accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ship follows a conventional automatic steering method using preset target points and constant turn rate, then the steering system is simple and easy to operate, but the ship cannot accurately maintain the desired route due to external factors like waves
Solution Approach 1:
The system performs preliminary actions by calculating the veering start point and veering line before the actual turn begins. The intermediate waypoint is calculated in advance based on the route and ship position, allowing the system to prepare steering commands ahead of time. This preliminary calculation enables more accurate route following by anticipating the needed steering adjustments before external disturbances like waves can cause deviations.
Solution Approach 2:
The system continuously monitors the ship's actual position and compares it with the desired route. The command steering angle is calculated based on the positional relation between the route and intermediate waypoint, creating a closed-loop feedback system. This feedback mechanism allows the ship to correct its trajectory in real-time, maintaining route accuracy despite external disturbances like waves.
2Reliability
If the ship starts veering at the calculated veering point, then the turning radius can be controlled, but the ship may still deviate from the desired route due to waves and other external factors
Solution Approach 1:
The system introduces an intermediate waypoint as a mediator between the current ship position and the target route. This intermediate waypoint serves as a reference point for calculating the command steering angle, providing a more reliable basis for steering control. By using this intermediary reference rather than directly targeting the final destination, the system can more reliably follow the desired route while maintaining operational simplicity.
Solution Approach 2:
The system calculates the veering start point and intermediate waypoint in advance before the actual turning begins. This preliminary action allows the steering system to be pre-configured with the correct parameters, improving reliability by ensuring the ship starts its turn at the optimal point. The advance calculation of the veering line and intermediate waypoint provides a robust foundation for reliable route following.
3Adaptability or versatility
If the system calculates veering point based on constant turn rate and ship speed, then the calculation is straightforward, but the ship cannot adapt to external disturbances like waves that occur after veering starts
Solution Approach 1:
The system employs continuous feedback by monitoring the ship's actual position and using this information to calculate the intermediate waypoint and command steering angle. This feedback loop enables the system to adapt to external disturbances like waves in real-time. The command steering angle is continuously updated based on the positional relation between the route and intermediate waypoint, allowing the ship to adjust its trajectory dynamically despite the complexity of real-time position monitoring.
Solution Approach 2:
The system transitions from a static, pre-calculated veering approach to a dynamic system where the intermediate waypoint and command steering angle are continuously updated based on the ship's actual position and the desired route. This dynamic adjustment allows the system to adapt to changing external conditions like waves, improving versatility while managing the complexity of real-time monitoring through systematic calculations.
Data Source
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AI summary
An automatic steering device (101) may include a route calculator (13), an intermediate waypoint calculating module (22), a command steering angle calculating module (23), and a steering controlling module (15). The route calculator (13) may calculate a route of a ship (10) based on positions of a plurality of target points (P, P1, P2). The intermediate waypoint calculating module (22) may calculate an intermediate waypoint (S) ahead of the ship (10). The command steering angle calculating module (23) may calculate a command steering angle based on a positional relation between the route and the intermediate waypoint (S). The steering controlling module (15) may control a steering mechanism (104) of the ship (10) based on the command steering angle.