Ship Steering Control Using Indirect Waypoints for Accurate Turning
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Solution Overview
Problem
Conventional automatic steering systems for ships may fail to accurately navigate along a desired route due to external factors such as waves, as they rely on predetermined turning rates and ship speed, which can lead to inaccurate veering and route deviations.
Innovation Solution
An automatic steering device with processing circuitry that calculates a route based on waypoints, estimates an intermediate waypoint ahead of the ship, and calculates a command steering angle based on the positional relation between the route and the intermediate waypoint, allowing for precise control of the rudder to ensure accurate turning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a predetermined turning rate and ship speed are used for automatic steering, then the steering control is simple, but the route accuracy deteriorates due to external factors such as waves
Solution Approach 1:
The system calculates an intermediate waypoint ahead of the ship's current position, anticipating where the ship will be at a future time point. This preliminary action allows the system to prepare and issue steering commands in advance, ensuring that the ship starts turning at the desired point even accounting for response time delays, thereby maintaining route accuracy without complicating the control mechanism
Solution Approach 2:
The system dynamically adjusts the intermediate waypoint position based on the ship's current position, course, and speed. By continuously updating the intermediate waypoint ahead of the ship's predicted position, the system adapts to changing conditions while maintaining a relatively simple control structure that achieves better route accuracy
2Speed
If the veering is started based on predetermined calculations, then the steering response is fast, but the turning point accuracy deteriorates due to ship response time delays
Solution Approach 1:
The system calculates the intermediate waypoint at a future time point ahead of the ship's current position, anticipating where the ship will be when the steering command takes effect. This allows the veering to be started at the correct desired point despite the ship's response time delay, maintaining turning point accuracy while enabling fast steering response
Solution Approach 2:
The system compensates for the ship's response time delay by proactively positioning the intermediate waypoint ahead of the current position. This beforehand cushioning approach ensures that when the steering command is issued and executed with a time delay, the ship still turns at the intended accurate location rather than deviating from the route
Data Source
AI summary
An automatic steering device may include a route calculator, an indirect target point calculating module, a command steering angle calculating module, and a steering controlling module. The route calculator may calculate a route of a ship based on positions of a plurality of target points. The indirect target point calculating module may calculate an indirect target point ahead of the ship. The command steering angle calculating module may calculate a command steering angle based on a positional relation between the route and the indirect target point. The steering controlling module may control a steering mechanism of the ship based on the command steering angle.