Actuator Position Sensor Using Screw-Nut Linear Measurement

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Solution Overview

Problem

Conventional actuator systems for position measurement are complex, bulky, and prone to inaccuracies due to the need for movement conversion via amplification or reduction gear mechanisms, making them difficult and expensive to manufacture.

Innovation Solution

The system replaces the reduction gearbox with a screw shaft and nut system, using a linear sensor to directly measure the axial position of the nut, mirroring the screw shaft and nut assembly, eliminating the need for rotary-to-linear conversion gears.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a reduction gearbox is used to convert rotary motion to linear motion for position sensing, then position measurement can be achieved, but the system becomes complex and bulky

Engineering Contradiction:
Improveposition measurement capabilityVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical reduction gearbox with a screw shaft and nut mechanism combined with a linear sensor. The screw shaft converts rotary motion to linear motion directly, eliminating the need for complex gear trains while maintaining position measurement capability through the linear sensor that reads the nut's position.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the reduction gearbox from the system, replacing it with a simpler screw-nut-linear sensor arrangement. This extraction eliminates unnecessary mechanical complexity while preserving the essential function of position sensing.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If multi-stage gear mechanisms are used for movement conversion, then position sensing is achieved, but manufacturing cost and difficulty increase

Engineering Contradiction:
Improveposition sensing accuracyVSAvoidmanufacturing difficulty
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent substitutes complex multi-stage gear mechanisms with a simple screw shaft and nut assembly paired with a linear sensor. This replacement dramatically simplifies manufacturing while maintaining accurate position sensing through direct linear measurement of the nut's position on the screw shaft.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a linear sensor to directly copy and measure the position information from the screw-nut mechanism, eliminating the need for complex intermediate gear conversions. This direct copying approach simplifies the system while preserving measurement accuracy.

Inventive Principle:
Principle #26Copying

3Measurement precision

If reduction gear mechanisms are used in the position sensor train, then position measurement is possible, but the system size increases

Engineering Contradiction:
Improveposition measurement capabilityVSAvoidsystem size
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent extracts and removes the bulky reduction gear mechanisms from the position sensor train, replacing them with a compact screw-nut-linear sensor arrangement. This extraction significantly reduces system volume while maintaining position measurement capability through the linear sensor's direct reading of nut position.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces volume-intensive gear mechanisms with a compact screw shaft and nut system combined with a linear sensor. The linear sensor provides accurate position measurement in a compact form factor, eliminating the need for large reduction gears.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If conventional position sensor assemblies with gear mechanisms are used, then position sensing is achieved, but inaccuracies occur in position sensing

Engineering Contradiction:
Improveposition sensing accuracyVSAvoidposition sensing accuracy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces gear-based position sensing with a direct linear sensing approach using a linear sensor on the screw-nut mechanism. This substitution eliminates gear backlash and mechanical play that cause inaccuracies, providing more reliable and accurate position sensing through direct linear measurement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a linear sensor to directly copy the position information from the screw-nut mechanism without intermediate mechanical conversions. This direct copying eliminates cumulative errors from multiple gear stages, improving position sensing accuracy and reliability.

Inventive Principle:
Principle #26Copying

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

This results in a smaller, simpler, and more accurate position sensor train that is easier and less costly to manufacture, providing reliable and precise position measurement.

Implementation Method 1

a screw shaft and nut system wherein the position of the nut feeds into a linear sensor that determines the stabilizer position based on the nut position. The screw shaft and nut system in the position sensor train is reflective of the screw shaft and nut system and the stabilizer movement end of the assembly whereby rotation of the shaft causes axial movement of the nut along the shaft.

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP3457091B1Actuator position sensor mechanism
Publication Date: 2023.04.19 RATIER FIGEAC SAS
  • EP3457091B1 patent drawingFigure 1
  • EP3457091B1 patent drawingFigure 2
  • EP3457091B1 patent drawingFigure 3

AI summary

The system of the present disclosure replaces the reduction gearbox of a conventional system with a screw shaft and nut system wherein the position of the nut feeds into a linear sensor that determines the stabilizer position based on the nut position. The screw shaft and nut system in the position sensor train is reflective of the screw shaft and nut system and the stabilizer movement end of the assembly whereby rotation of the shaft causes axial movement of the nut along the shaft.