Hull Inspection Positioning Using Encoding Wheels
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Solution Overview
Problem
Current hull inspection systems lack precision for positioning a movable machine relative to a reference point both above and below the water line, leading to inaccurate defect mapping and unnecessary maintenance, and are unable to operate effectively over the entire vessel surface with the desired precision of 10 cm.
Innovation Solution
The system employs coaxial encoding wheels and inclinometers to measure linear movements and inclinations, integrated with a processing unit to calculate and integrate position variations, allowing precise positioning both in air and water, while maintaining a lightweight and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic positioning means are used underwater, then positioning can be achieved, but precision is limited to 50 cm and requires buoys remote from the hull
Solution Approach 1:
The patent replaces acoustic positioning (which requires external buoys and has 50 cm precision) with a mechanical encoding wheel system that directly measures the machine's movement along the hull. The encoding wheels count revolutions and fractions thereof, providing 10 cm precision without requiring external reference points or buoys, thus enabling inspection right at the quay side.
2Measurement precision
If DGPS positioning is used in air, then positioning can be achieved, but precision is limited to 50 cm
Solution Approach 1:
The patent replaces DGPS optical positioning (which has 50 cm precision) with a mechanical encoding wheel system. The encoding wheels are driven by the machine's movement along the hull and directly convert mechanical displacement into positional information, achieving 10 cm precision with a simpler system that doesn't require external reference markers or complex signal processing.
3Measurement precision
If optical positioning with reference station is used, then precision within centimeters is achieved, but the system is complex and requires ground infrastructure
Solution Approach 1:
The patent extracts the positioning function from complex external infrastructure (optical reference stations, ground markers, GPS satellites) and implements it within the machine itself through encoding wheels. This self-contained mechanical positioning system achieves 10 cm precision without requiring external reference points or complex infrastructure, simplifying the overall system.
4Weight of moving object
If the machine is made lightweight and compact for correct operation, then adhesion and mobility are maintained, but high-precision positioning becomes difficult
Solution Approach 1:
The patent uses a mechanical encoding wheel system that is naturally lightweight since it only needs to measure rotation rather than provide positioning force. The encoding wheels are driven passively by the machine's movement, requiring minimal mass. This mechanical measurement approach achieves 10 cm precision without the weight penalty of inertial units or complex electronic positioning systems.
Data Source
AI summary
A system for inspecting the hull of a vessel includes a movable machine which moves on the hull and a positioning element to determine an instantaneous position of the machine in a reference point. The positioning element includes: —first and second coaxial encoding wheels separated from each other by an inter-wheel spacing and in contact with the hull, and are capable of measuring first and second linear movements of the machine; —first and second inclinometers arranged so as to measure inclinations, relative to a reference direction, of a first axis and a second axis of a frame of reference linked to the machine; and, —a processing element, which receives data measured in order to calculate a variation of the position of the machine in the frame of reference, and in order to integrate the successive position variations in order to obtain the instantaneous position of the machine.