Auxiliary Water Vessel Position Locking in GPS-Denied Waters
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Solution Overview
Problem
Existing systems for maintaining a watercraft's stationary position fail when GPS signals are unavailable, particularly in deep water or adverse weather conditions, as they rely on satellite signals or locking onto the bottom surface, which are not always feasible.
Innovation Solution
A dynamic positioning system uses an auxiliary water vessel as a reference point, measuring its velocity and the water current to estimate the watercraft's movement, allowing the navigation system to control the propulsion system and maintain a stationary position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS signals are used to hold the watercraft stationary, then positioning accuracy is improved, but the system fails when GPS signals are unavailable in deep water or adverse weather conditions
Solution Approach 1:
The patent introduces an auxiliary water vessel as an intermediary reference object between the watercraft and the water body. Instead of directly relying on GPS satellites or the water bottom, the system uses the auxiliary vessel (which can be tracked via acoustic signals) as a mediator to establish position references, enabling operation in environments where GPS is unavailable
Solution Approach 2:
The patent replaces the electromagnetic GPS signal-based positioning system with an acoustic-based relative velocity measurement system. Acoustic signals are used to measure the relative velocity between the watercraft and the auxiliary water vessel, substituting the satellite-based electromagnetic system with an underwater acoustic system that works in deep water and adverse weather
2Reliability
If the system locks onto the bottom surface to maintain position, then positioning is achieved in GPS-denied environments, but this method is not feasible in deep water
Solution Approach 1:
The patent transitions from a two-dimensional bottom-locking approach to a three-dimensional acoustic reference system. By deploying an auxiliary water vessel at a specific depth and using acoustic signals to measure relative velocity in three-dimensional space, the system can operate in deep water where bottom-locking is not feasible
3Reliability
If an auxiliary water vessel is deployed as a reference point, then positioning reliability is improved in GPS-denied environments, but device complexity increases
Solution Approach 1:
The auxiliary water vessel serves multiple functions: it acts as a reference point for velocity measurement, a buoyant platform for acoustic signal reflection, and a configurable reference object that can be deployed or recovered as needed. This multi-functionality reduces the need for separate specialized equipment for each function
Solution Approach 2:
The auxiliary water vessel is designed to be deployable and recoverable. When GPS is available, the system can operate without the auxiliary vessel. When GPS fails, the vessel is deployed as needed, used for the duration of the GPS-denied operation, and then recovered, allowing the system to maintain simplicity when the complex function is not needed
Data Source
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AI summary
Apparatus and methods for holding the position of a watercraft stationary. An exemplary method includes measuring a velocity of an auxiliary water vessel relative to the watercraft with a first sensor, where the auxiliary water vessel is deployed at a depth between the watercraft and a ground surface of the body of water. The method further includes measuring a velocity of current in the body of water relative to the watercraft with a second sensor. The method further includes processing the velocity measurement of the auxiliary water vessel and the velocity measurement of the current to determine a net movement of the watercraft, and controlling a propulsion system to compensate for the net movement of the watercraft to hold the watercraft in a stationary position.