Sonar Imaging Stabilization via Visual Odometry

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Solution Overview

Problem

Current 3D sonar imaging technologies face challenges in maintaining accurate real-time navigational data during surveys, particularly when GPS signals drop out, leading to inaccuracies in infrastructure inspections and hull examinations due to Inertial Measurement Unit (IMU) drift and lack of external reference points.

Innovation Solution

The integration of video photogrammetry with IMU data and synchronized camera systems to calculate camera motion and correct sonar image viewpoints, allowing for real-time 3D scene reconstruction without relying on GPS signals, using keypoint matching and optical flow algorithms to stabilize images and maintain navigational data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If GPS signals are used for navigation during sonar surveys, then navigational data accuracy is maintained, but the system fails in GPS-denied environments

Engineering Contradiction:

Improvenavigational data accuracyVSAvoidoperation in GPS-denied environments

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces an intermediary system (visual odometry with feature tracking) that mediates between the loss of GPS signals and the need for continuous navigational data. The system uses visual features in the environment as intermediate reference points to calculate vessel position and orientation when GPS is unavailable, allowing the sonar system to maintain accurate navigation in GPS-denied environments.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If Inertial Measurement Units are used for navigation, then the system operates without GPS, but IMU drift causes navigational data inaccuracies over time

Engineering Contradiction:

Improveoperation without GPSVSAvoidnavigational data accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where visual features are continuously tracked and used to correct IMU drift. The system constantly compares the expected position (from IMU integration) with the actual position (from visual feature tracking) and uses this feedback to correct accumulated errors, maintaining long-term navigational accuracy without GPS.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent merges multiple navigation systems (IMU and visual odometry) into a unified navigation solution. By combining the short-term accuracy of IMU with the long-term stability of visual feature tracking, the system achieves both GPS independence and sustained navigational precision, resolving the contradiction between operational versatility and measurement precision.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If sonar receivers move during data collection, then the survey area can be covered, but image stability and positioning accuracy deteriorate

Engineering Contradiction:

Improvesurvey coverageVSAvoidpositioning accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical stabilization methods (physical mounting systems) with computational stabilization using visual odometry. Instead of mechanically fixing the sonar receiver's position, the system uses algorithmic correction based on tracked visual features to compensate for vessel motion, maintaining positioning accuracy while allowing the vessel to move freely to cover the survey area.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables accurate and stable real-time 3D sonar imaging by correcting for vessel motion and maintaining navigational data, even in GPS-denied environments, improving the precision and reliability of underwater and above-water object positioning and mapping.

Implementation Method 1

A series of sonar pings are sent into an insonified volume of water and reflected or scattered from submerged object(s) in the insonified volume of water

Methodology Applied

Scientific EffectSound wave reflection: Reflection

Implementation Method 2

One or more large sonar receiver arrays of sonar detectors are arranged below the surface of the water and record the phase and amplitude of reflected sonar ping sound waves

Methodology Applied

Scientific EffectSound: Sound

Implementation Method 3

The measuring device(s) map relative locations of objects above the surface of the volume of water to determine the spatial coordinates of the measuring devices with respect to the locations of the above water objects

Methodology Applied

Scientific EffectPhotogrammetry: Photogrammetry

Implementation Method 4

using keypoint matching and optical flow algorithms to stabilize images and maintain navigational data

Methodology Applied

Scientific EffectOptical flow:

Data Source

PatentUS11789146B2Combined method of location of sonar detection device

Publication Date: 2023.10.17 CODA OCTOPUS GROUP INC

AI summary

A method of real time three dimensional (3D) sonar imaging is disclosed, where large array of sonar signal detectors images an underwater object and electromagnetic measuring means fixed in a known position with respect to the large array of sonar detectors measure the position of an above water object which has a known position with respect to the underwater object. The position of the sonar detector may be corrected to give a stable image of the underwater object from ping to ping of the sonar imaging system.