Body-Worn Tracking Device Boundary Compliance via Motion Sensor Net Distance

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Solution Overview

Problem

Body-worn tracking devices (BWTDs) used for monitoring criminal offenders often face challenges in determining compliance with geographic boundaries when they lose connectivity to Global Navigation Satellite Systems (GNSS), leading to unnecessary notifications and resource burdens on both the device and law enforcement.

Innovation Solution

The BWTD determines whether it is within a bounded geographic area by calculating the net distance between the last known location and the current location using data from motion sensors, rather than relying solely on GNSS signals, thereby reducing unnecessary notifications and conserving resources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the BWTD continuously monitors location using GNSS and outputs notifications whenever GNSS signal is lost, then compliance detection coverage is improved, but device computing resources are excessively consumed and unnecessary notifications are generated

Engineering Contradiction:

Improvecompliance detection coverageVSAvoiddevice computing resources

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system uses motion sensor data to self-determine location changes when GNSS is unavailable, allowing the device to autonomously assess boundary compliance without external assistance or continuous GNSS signaling, thereby conserving energy while maintaining monitoring capability

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system switches between different location determination methods based on GNSS signal availability - using GNSS coordinates when available and motion sensor-derived net distance when unavailable - optimizing resource usage by adapting to environmental conditions

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the BWTD outputs notifications every time it loses GNSS connectivity, then real-time compliance monitoring is improved, but the number of notifications and data transfers increases unnecessarily

Engineering Contradiction:

Improvereal-time compliance monitoringVSAvoidnumber of notifications

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The system performs partial monitoring using motion sensors only when necessary (when GNSS is unavailable), rather than continuously using both methods or notifying on every GNSS loss, thereby reducing notification quantity while maintaining essential monitoring coverage

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system uses feedback from motion sensor data to determine whether a boundary violation actually occurred during GNSS outages, enabling intelligent notification generation based on actual compliance status rather than mere signal loss

Inventive Principle:

Principle #23Feedback

3Measurement precision

If the BWTD calculates total distance traveled instead of net distance, then movement tracking is improved, but false violations are generated when the offender returns to the bounded area

Engineering Contradiction:

Improvemovement trackingVSAvoidcompliance detection accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

Instead of tracking the cumulative path length (total distance), the system inverts the approach by tracking the straight-line displacement from the last known valid position (net distance), which directly indicates whether the offender has left the permitted area without false positives from circular movement

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

This approach accurately determines when the offender is outside permitted areas, reducing the number of notifications and data transfers, enhancing battery life, and minimizing the time and resources required for supervision.

Implementation Method 1

A body-worn tracking device (BWTD) determines whether it is within a bounded geographic area when the BWTD is unable to determine its current location by using a Global Navigation Satellite System (GNSS)

Methodology Applied

Scientific EffectSatellite-based navigation:

Implementation Method 2

The BWTD may lose connectivity to one or more GNSS satellites (e.g., GPS satellites) when the monitored person wearing the BWTD enters his or her place of employment

Methodology Applied

Scientific EffectMotion sensing: Accelerometer

Data Source

PatentEP3638118B1Geographic boundary compliance detection using body-worn offender monitoring electronic devices

Publication Date: 2024.02.14 ATTENTI ELECTRONIC MONITORING LTD

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AI summary

A body-worn tracking device (BWTD) includes a global navigation satellite system (GNSS) device, at least one motion sensor, at least one processor, and at least one memory device. The at least one memory device includes instructions that, when executed by the at least one processor, cause the at least one processor to determine, based on data generated by the at least one motion sensor, a net distance between the last known location of the BWTD and a current location of the BWTD. The instructions further cause the at least one processor to determine, based on the net distance, whether the BWTD is within a bounded area that includes the last known location; and responsive to determining that BWTD is not within the bounded area, output an indication that the BWTD is not within the bounded area.