Rotational Speed and Position Detection Using RFID Transponders

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Solution Overview

Problem

Existing methods for determining the rotational speed and position of rotating devices, such as crankshafts, rely on pattern recognition which is limited to when the device is rotating and may not provide accurate position determination when stationary.

Innovation Solution

A system utilizing radio-frequency identification (RFID) technology with a transceiver module and transponders arranged along the perimeter of the rotating device, generating an electromagnetic field that is damped as transponders pass through, allowing for speed and position determination based on the number of damped field occurrences during a period.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pattern recognition methods are used to determine rotational position, then position can be determined during rotation, but the method fails when the device is stationary

Engineering Contradiction:

Improveposition determination reliabilityVSAvoidoperational condition coverage

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical pattern recognition system with an electromagnetic field-based detection system. The transceiver generates an electromagnetic field that interacts with transponders on the rotating device, allowing detection of both stationary and rotating positions through field damping effects rather than mechanical pattern analysis.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes the detection parameter from analyzing pulse patterns during rotation to measuring electromagnetic field damping characteristics. This parameter change enables the system to detect transponder positions whether the device is stationary or rotating, as the electromagnetic field interaction occurs in both states.

Inventive Principle:

Principle #35Parameter changes

2Speed

If Hall-effect sensors with gear teeth are used, then rotational speed can be measured during operation, but the system complexity increases

Engineering Contradiction:

Improverotational speed measurementVSAvoidsensor system complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent extracts the measurement function from a complex mechanical sensor system and implements it through a simpler electromagnetic field interaction. The transceiver and transponders replace the Hall-effect sensor and gear tooth mechanism, maintaining speed measurement capability while reducing mechanical complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The electromagnetic field acts as an intermediary between the transceiver and the transponders on the rotating device. This field-based mediation simplifies the direct mechanical coupling required in Hall-effect sensor systems, reducing overall system complexity while maintaining measurement functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If multiple transponders are arranged on the rotating device, then position resolution is improved, but the quantity of components increases

Engineering Contradiction:

Improveposition determination precisionVSAvoidnumber of transponders

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

Each transponder serves multiple functions: it provides position identification, enables speed calculation through timing, and works with the electromagnetic field for detection. This multi-functionality allows the system to achieve high measurement precision with a reasonable number of components, as each transponder contributes to multiple measurement aspects simultaneously.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 determination of rotational speed and position of rotating devices, including when stationary, with improved resolution and consistency, applicable to various systems like vehicles and industrial machinery.

Implementation Method 1

The transceiver module generates an electromagnetic (EM) field using an antenna

Methodology Applied

Scientific EffectElectromagnetic field generation: Electromagnetic Induction

Implementation Method 2

Each of the N transponders damps the EM field when passing through the EM field

Methodology Applied

Scientific EffectElectromagnetic field damping: Electromagnetic Induction

Data Source

PatentUS8334687B2Systems and methods for measuring rotational speed and position of a rotating device

Publication Date: 2012.12.18 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A system includes a transceiver module and a rotating device. The transceiver module generates an electromagnetic (EM) field using an antenna. The rotating device includes N transponders arranged such that each of the N transponders passes through the EM field during one revolution of the rotating device. Each of the N transponders damps the EM field when passing through the EM field. The transceiver module determines a rotational speed of the rotating device based on a number of times the EM field is damped during a period. N is an integer greater than or equal to 1.