AUV Navigation with 4π Sonar Array and Segmented Thrust
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Solution Overview
Problem
Autonomous underwater vehicles (AUVs) face challenges in navigating labyrinthine environments due to limited geometric sensor capabilities, lack of maneuverability, and susceptibility to multipath spoofing, leading to potential loss in complex 3D settings like rock caverns and ice sheets, where external navigation aids are unavailable.
Innovation Solution
An axi-symmetric framing system with a narrow-beam sonar array distributed over a 4π-steradian viewing angle, allowing for simultaneous and asynchronous firing of transducers to create a high-resolution map of the environment, enabling independent navigation and rejecting multipath echoes, and utilizing a SLAM methodology for accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a torpedo-shaped AUV with aft propeller is used, then the vehicle can maintain simple structure and oceanographic research capability, but it suffers from long turning radius and poor maneuverability in labyrinthine environments
Solution Approach 1:
The vehicle is divided into multiple independent propulsion units (four thrust vectoring propulsion units) distributed at different locations on the hull, replacing the single aft propeller. This segmentation allows independent control of each propulsion unit, enabling complex maneuvers such as rotation, translation, and positioning in three-dimensional space, thereby dramatically improving maneuverability while maintaining structural simplicity through modular design
Solution Approach 2:
The propulsion system transitions from two-dimensional (single aft propeller providing forward/reverse motion) to three-dimensional control by distributing four propulsion units at different locations and orientations on the hull. Each unit can be independently controlled to provide thrust in different directions, enabling the vehicle to maneuver freely in three-dimensional labyrinthine environments including vertical movements and rotational operations
2Measurement precision
If downward-looking swath-type sonar systems are used, then the vehicle can perform bathymetric measurements, but it lacks complete geometric knowledge of the environment and is susceptible to multipath spoofing
Solution Approach 1:
The sonar system is segmented into multiple independent sonar devices (at least four, preferably six or more) positioned at different locations on the vehicle hull. Each sonar device provides measurements from a different spatial perspective, collectively forming a complete three-dimensional geometric model of the environment. This segmentation eliminates the single-point failure mode and multipath spoofing vulnerability of traditional single-sonar systems
Solution Approach 2:
The sonar measurement system transitions from two-dimensional downward-looking swath mapping to three-dimensional omnidirectional geometric sensing. By positioning sonar devices around the entire vehicle hull, the system captures spatial information from all directions (360-degree horizontal coverage and vertical coverage), enabling complete environmental reconstruction and reliable navigation in complex three-dimensional labyrinthine environments through simultaneous localization and mapping
3Device complexity
If traditional AUV design with single aft propeller is used, then the vehicle can maintain simple propulsion system, but it becomes vulnerable to propeller snagging and system failure in complex terrains
Solution Approach 1:
The propulsion system is segmented into multiple independent thrust vectoring propulsion units distributed around the vehicle hull, replacing the single aft propeller. Each unit operates independently with its own control system, eliminating the single-point failure vulnerability. If one unit fails or becomes snagged, the other units can compensate to maintain vehicle control and mission completion
Solution Approach 2:
The propulsion system changes from fixed-direction thrust to variable-direction thrust through thrust vectoring capability. Each propulsion unit can independently adjust its thrust direction and magnitude, providing six degrees of freedom control. This parameter flexibility allows the vehicle to navigate complex terrains by adjusting propulsion vectors to avoid obstacles and maintain stability, dramatically improving reliability in labyrinthine environments
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 solution provides reliable navigation and mapping in labyrinthine environments by constructing a best-fit geometry map, reducing drift and avoiding external navigation dependencies, thereby enhancing the vehicle's ability to survive and operate effectively in unexplored complex terrains.
Implementation Method 1
A narrow-beam sonar array is mounted to the axi-symmetric framing system and includes a plurality of simultaneously-fireable and/or asynchronously-fireable transducers distributed substantially evenly over a 4π-steradian viewing angle
Data Source
AI summary
An underwater vehicle including an axi-symmetric framing system rotatable about a centerline to define a shell of revolution having a uniformly-convex outer boundary. A narrow-beam sonar array is mounted on the axi-symmetric framing system, and includes a multitude of simultaneously-fireable and/or asynchronously-fireable transducers distributed substantially evenly over a 4π-steradian viewing angle. The present invention provides the necessary configuration for a vehicle wherein an internal algorithm can compare a “new” geometry to an “old” geometry collected earlier to construct a best fit of the new world map with the old world map and locate the vehicle within the context of the new world map. This then provides a completely independent mechanism for correction of the gradual drift in x and y that is not dependent on any form of external navigation aid.