EM Tracking Power Management via Jitter Metrics

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Solution Overview

Problem

Conventional electromagnetic (EM) tracking systems consume high power due to the need for strong EM fields to maintain accurate tracking, which limits their utility in battery-powered devices and applications where power efficiency is crucial.

Innovation Solution

The EM tracking system adjusts its power mode based on metrics correlated with jitter and sleep conditions, such as distance and communication status, to reduce power consumption by dynamically adjusting transmit power and placing modules into sleep modes when not needed, thereby conserving energy without compromising tracking accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the transmitter generates the EM field at high signal strength to minimize jitter and ensure accurate tracking, then tracking accuracy is improved, but power consumption increases

Engineering Contradiction:
Improvetracking accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the transmit power adjustable rather than fixed. The system dynamically changes the EM field signal strength based on real-time jitter metrics and sleep conditions, transitioning between high power (when jitter is high) and low power (when jitter is acceptable or sleep conditions are met), thereby resolving the contradiction between maintaining tracking accuracy and reducing power consumption

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the physical parameter of EM field signal strength (power level) based on measured jitter conditions. By monitoring jitter metrics and adjusting the transmit power parameter accordingly, the system maintains sufficient tracking accuracy only when necessary, reducing overall power consumption while preserving measurement precision when required

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the transmitter continuously operates at high power to maintain tracking accuracy, then tracking reliability is improved, but battery life deteriorates

Engineering Contradiction:
Improvetracking reliabilityVSAvoidbattery life
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent implements periodic action by continuously monitoring jitter metrics and sleep conditions, then periodically adjusting the transmit power level. The system operates in cycles of high power (when jitter exceeds threshold or sleep conditions are not met) and low power (when jitter is acceptable and sleep conditions are satisfied), maintaining tracking reliability only when necessary and extending battery life through periodic power adjustments

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent employs feedback by measuring jitter conditions and using this information to control transmit power levels. The system creates a closed-loop control where jitter metrics feed back to the power management module, which adjusts power consumption accordingly, ensuring tracking reliability is maintained only when jitter conditions require it, thereby preserving battery life

Inventive Principle:
Principle #23Feedback

3Measurement precision

If the EM tracking system operates continuously to maintain accurate tracking, then tracking precision is improved, but power consumption increases

Engineering Contradiction:
Improvetracking precisionVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by stationary object

Solution Approach 1:

The patent applies partial action by operating the EM tracking system at reduced power levels when jitter conditions permit, rather than continuously operating at full power. The system performs sufficient tracking function to maintain acceptable precision only when necessary, allowing partial operation (low power mode) when full power is not required, thereby reducing overall energy consumption while maintaining adequate tracking precision

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent changes the operational parameter of power consumption based on real-time jitter measurements. By adjusting the EM field signal strength parameter according to measured precision requirements, the system maintains adequate tracking precision only when jitter exceeds acceptable thresholds, reducing power consumption during periods when lower precision is acceptable or sleep conditions are met

Inventive Principle:
Principle #35Parameter changes

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 approach reduces overall power consumption while maintaining jitter within acceptable limits, enabling the use of EM tracking systems in a wider range of devices, including those relying on battery power, and enhancing user experience by optimizing power usage based on real-time requirements.

Implementation Method 1

The transmitter (Tx) and receiver (Rx) are distributed over different devices, including a 'base device' that tracks the position and/or orientation of a 'mobile device'... The transmitter generates an EM field on a tri-axis coil to induce a current on a second tri-axis coil at a receiver

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Conventional EM tracking systems typically consume a relatively high amount of power. In particular, because an EM tracking system depends on near-field magnetic coupling, EM signal strength falls off sharply with distance

Methodology Applied
Scientific EffectNear-field magnetic coupling:

Data Source

PatentEP3589967B1Power management for electromagnetic position tracking systems
Publication Date: 2022.03.23 GOOGLE LLC
  • EP3589967B1 patent drawingFigure 1
  • EP3589967B1 patent drawingFigure 2
  • EP3589967B1 patent drawingFigure 3

AI summary

An EM pose tracking system (100) controls a power mode by adjusting a transmit power of an EM transmitter (103) based on a metric correlated with jitter in the EM readings. Such a metric includes metrics such as estimated noise computed from received EM data, a computed distance between the transmitter and a receiver (105), a measured signal power between the transmitter and the receiver, and the like. By adjusting the transmit power based on the jitter metric, the EM tracking system can reduce overall power consumption at a device that employs the EM tracking system, thus allowing the system to be used in a wider variety of devices and improving the user experience with those devices.