Coreless Transformer Inductive Sensor for Telescope Mirror Positioning

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Solution Overview

Problem

Existing non-contact measurement systems for relative displacement between objects, particularly in giant segmented mirror telescopes, face challenges due to sensitivity to dust and condensation, and instability in temperature and time due to parasitic impedances in inductive sensors.

Innovation Solution

A high-precision non-contact measurement system using a coreless transformer principle with mutual inductance between transmitter and receiver coils, where the voltage generated across the receiver coil is proportional to the mutual inductance, reducing sensitivity to parasitic impedances and improving measurement stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If capacitive displacement sensors are used for non-contact measurement, then measurement precision is improved, but sensitivity to dust and condensation increases

Engineering Contradiction:

Improverelative positioning measurement precisionVSAvoidsensitivity to dust and condensation

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces capacitive sensors with inductive sensors that use magnetic fields instead of electric fields for measurement. The inductive sensor comprises a transmitter coil that generates a magnetic field and a receiver coil that detects changes in this field, eliminating the need for direct electrical contact and reducing sensitivity to dust and condensation while maintaining measurement precision for relative positioning of mirror segments.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If inductive sensors with impedance measurement are used, then insensitivity to dust and condensation is improved, but measurement stability with temperature and time deteriorates due to parasitic impedances

Engineering Contradiction:

Improveinsensitivity to dust and condensationVSAvoidmeasurement stability with temperature and time

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback mechanism where the received signal from the receiver coil is processed to generate a detection signal that compensates for temperature and time variations. The system continuously monitors and adjusts for parasitic impedances through signal processing, maintaining measurement stability while preserving the advantage of dust and condensation insensitivity.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the measurement parameter from direct impedance measurement to voltage measurement across the receiver coil. By measuring the voltage generated in response to changing magnetic flux rather than direct impedance, the system eliminates the influence of parasitic resistances and achieves stable measurements despite temperature and time variations.

Inventive Principle:

Principle #35Parameter changes

3Difficulty of detecting and measuring

If traditional inductive sensors with coils connected to zero impedance are used, then eddy current measurement capability is improved, but measurement stability deteriorates due to superimposed parasitic impedances

Engineering Contradiction:

Improveeddy current measurement capabilityVSAvoidposition measurement stability

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent inverts the traditional inductive sensor configuration by placing the receiver coil with high impedance rather than zero impedance. This inversion allows the receiver to measure voltage directly without the parasitic impedances that plague traditional designs, while still utilizing eddy current principles for detecting relative position through changes in magnetic flux.

Inventive Principle:

Principle #13The other way round (Inversion)

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 provides stable and precise measurement of relative displacement, insensitive to dust and condensation, and maintains high accuracy in temperature and time, suitable for large segmented mirror telescopes.

Implementation Method 1

The voltage generated across the receiver coil is proportional to the mutual inductance

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

An alternating voltage is generated across the terminals of the receiving coil proportional to the mutual inductance

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP1904806B2Inductive non-contact measurement of a relative movement or relative positioning of a first object relative to a second object

Publication Date: 2016.11.16 NANOTEC SOLUTION

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AI summary

The invention concerns a method for non-contact measurement of a relative movement or relative positioning of a first object with respect to a second object such as segmented mirrors of a giant telescope, which consists in: exciting at least one transmitter coil, placed on the first object, through an alternating current signal; detecting at least one alternating current voltage (va), generated by mutual inductance in at least one receiver coil placed on said second object, said at least one receiver coil being placed in a magnetic field generated by said at least one transmitter coil; and determining the relative movement of the first object with respect to the second object based on said at least one voltage generated on said at least one receiver coil.