Magnetic Sensor Array for Precise Hole Location
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Solution Overview
Problem
Existing methods for locating non-visible objects, such as holes in opaque surfaces, are inaccurate and impractical, especially in applications requiring tight tolerance limits like aircraft construction, where incorrect alignment can lead to safety failures.
Innovation Solution
A method using a variable strength magnetic field sensed by an array of Hall effect sensors, which are geometrically associated with a machining guide, to determine the displacement and accurately locate the object behind the opaque surface, allowing precise alignment and fixing of the machining guide for drilling or other processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional methods like tapping the wall or using magnets are used to locate non-visible objects, then the method is simple to perform, but the location accuracy is poor
Solution Approach 1:
The patent replaces mechanical location methods (tapping, visual inspection) with electromagnetic field-based detection. A magnetic field generator creates a magnetic field that penetrates the opaque surface, and magnetic sensors detect field strength variations to precisely locate features like holes or cavities behind the surface, achieving high accuracy without complex mechanical procedures
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the operator and the hidden object. The magnetic field penetrates the opaque surface (plasterboard, aircraft skin) and carries information about the location of hidden features to sensors, enabling accurate detection without direct contact or visual access to the target
2Ease of operation
If templates are used to locate holes from the outside, then the operator can see the hole positions, but the method fails for thick or complex materials and does not ensure accurate perpendicular drilling
Solution Approach 1:
The patent replaces mechanical template-based location with magnetic field detection. Magnetic sensors scan the surface and detect variations in magnetic field strength caused by hidden features (holes, cavities), automatically determining precise locations and orientations without physical contact with the hidden features, ensuring accuracy even through thick or complex materials
Solution Approach 2:
The patent transitions from two-dimensional template placement on the surface to three-dimensional magnetic field penetration through the material. The magnetic field extends through the thickness of the material, allowing detection of features at any depth, while the sensor array geometry enables determination of both lateral position and orientation for accurate perpendicular drilling
3Measurement precision
If pre-formed holes in ribs or spars are used as guides, then hole alignment is possible, but space constraints make this awkward and inaccuracies creep in
Solution Approach 1:
Instead of using hidden features (pre-formed holes) as guides for creating new features, the patent inverts the approach: magnetic sensors detect the magnetic field signature of hidden features to determine their precise location, then guide the creation of new features (drilling holes) at the detected positions. This eliminates the need for physical contact with hidden features and allows accurate location even when space is constrained
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 rapid and accurate location of non-visible objects, ensuring precise alignment and reducing the risk of assembly failures by providing a reliable and intuitive method for locating holes in thick or complex materials like aircraft skins.
Implementation Method 1
sensing the magnetic field strength at a plurality of positions relative to the object using an array of Hall effect magnetic sensors
Data Source
AI summary
Non-visible objects which differ in their physical properties from their surroundings by association with a variable strength magnetic field may be detected by a suitable array of sensors which can be moved relative to the object in question. By analyzing the signals from the plurality of the sensors in the array, the position of the object can be deduced relative to the array and the array moved to enable a machining guide thereon to be aligned with the non-visible object. The system is of particular value in locating apertures in wing spars when attempting to fix the skin of the wing on to them where it is important to be able to locate the correct point at which to drill a hole through the skin to coincide with the hole in the spar. By defining a magnetic field in the vicinity of the hole to identify the hole magnetically and using an array of magnetic field sensors in a base with an aperture, it is possible to shift the array so that the aperture is precisely aligned with the non-visible hole.