Acoustic Vector Sensor With Slip-Ring Gimbal
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Solution Overview
Problem
Existing acoustic vector sensors (AVS) are limited by high cost, mechanical resonances at low frequencies, and mechanical hard-stops that restrict axial rotation and cause sticking issues, making them inadequate for applications requiring higher frequency sensitivity and flexible deployment.
Innovation Solution
A horizontal acoustic vector sensor system with a dome-shaped housing, a gimbal assembly containing orthogonally arranged seismometers, and integrated omni-directional hydrophones, utilizing fluid damping and electrical slip-rings to eliminate mechanical resonances and hard-stop limitations, allowing for higher frequency sensitivity and flexible deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical hard-stop is used to limit axial rotation of the gimbal system, then wiring wrapping is prevented, but the sensor cannot operate properly for certain axial-rotation angles and may stick to the hard-stop
Solution Approach 1:
The patent replaces the mechanical hard-stop system with an electrical slip-ring system. The slip-ring allows continuous electrical connection while the gimbal rotates freely without mechanical contact, eliminating both the hard-stop limitations and wiring wrapping issues. This substitution of mechanical constraint with electrical flexibility resolves the contradiction between wiring integrity and rotation range.
Solution Approach 2:
The slip-ring acts as an intermediary that transfers electrical signals continuously during rotation without requiring mechanical contact or hard-stops. It mediates between the rotating gimbal and the external electronics, enabling unlimited axial rotation while maintaining reliable electrical connection, thus resolving the contradiction.
2Measurement precision
If a large number of elements are used in the sensor assembly, then sensitivity and directionality are improved, but the device becomes too large to accommodate packaging and deployment constraints
Solution Approach 1:
The patent implements a nested gimbal structure where multiple seismometer elements are arranged concentrically in orthogonal planes. The inner gimbal contains seismometers in one orientation, while the outer gimbal contains seismometers in perpendicular orientations. This nesting allows multiple sensing elements to occupy the same spatial volume, achieving high sensitivity without increasing the overall device footprint.
Solution Approach 2:
The patent transitions from a single-plane array to a three-dimensional orthogonal arrangement of seismometer pairs. By distributing elements across multiple spatial dimensions (x, y, z axes) through the gimbal structure, the system achieves enhanced directional sensitivity while maintaining a compact form factor through efficient spatial utilization.
3Reliability
If the prior art OBS design is used, then mechanical resonances occur at relatively low frequencies, but the usable signal response becomes unreliable for frequencies greater than one-half of the mechanical resonant frequency
Solution Approach 1:
The patent replaces the mechanical hard-stop and rigid gimbal structure with a flexible fluid-damped suspension system. The fluid damping mechanism eliminates mechanical resonances by providing continuous viscous damping, allowing the sensor to reliably operate at frequencies well above the mechanical resonant frequency of the prior art design.
Solution Approach 2:
The patent changes the mechanical parameters of the gimbal system by introducing fluid damping, which modifies the resonant frequency characteristics and reduces the amplitude of mechanical resonances. This parameter change enables reliable operation at higher frequencies by shifting the resonant behavior away from the operating frequency range.
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 achieves improved sensitivity and frequency range, reduced size, and unlimited axial rotation, enabling effective deployment in challenging environments and overcoming the limitations of prior art AVS designs.
Implementation Method 1
a sensor assembly and an outer gimbal, the sensor assembly including multiple pairs of seismometers
Implementation Method 2
at least one omni-directional hydrophone integrated into the endcap
Implementation Method 3
utilizing fluid damping and electrical slip-rings to eliminate mechanical resonances
Data Source
AI summary
A horizontal acoustic vector sensor system described herein includes a housing which has a gimbal assembly therein which is attached to a sensor assembly which has multiple pairs of seismometers that arranged orthogonally to one or more neighboring pairs of seismometers, along an approximately horizontal axis. The gimbal assembly with sensor assembly are enclosed within the housing by an endcap which includes an electronics assembly. The multiple pairs of seismometers are wired to the electronics assembly through a slip-ring which allows for movement of the gimbal assembly without entangling the wires. The horizontal acoustic vector sensor system further includes at least one omni-directional hydrophone integrated into the endcap.