Step-Based Positioning With Range and Inertial Data Fusion

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Solution Overview

Problem

Existing positioning systems using acoustic signals face challenges in environments with high signal-to-noise ratios due to uncertainty in identifying the source of acoustic signals, leading to inaccurate position estimates for mobile devices.

Innovation Solution

A positioning system that combines external-range data with acceleration data from a mobile device's accelerometer to determine step-distance data, using an optimization problem with cost terms that enhance positioning accuracy by integrating both sources of information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If acoustic signals are used for positioning in environments with highly reflective surfaces, then positioning coverage is improved, but measurement precision deteriorates due to uncertainty in identifying the source of acoustic signals

Engineering Contradiction:

Improvepositioning coverageVSAvoidposition estimate accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent combines acoustic signal-based positioning with inertial sensor-based positioning (accelerometer, gyroscope, magnetometer) into a unified positioning system. The inertial measurement unit (IMU) provides complementary positioning data that does not depend on acoustic signal identification, thereby maintaining measurement precision while preserving the extended positioning coverage provided by acoustic transmitters in reflective environments.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces an intermediary fusion algorithm that processes both acoustic positioning data and inertial sensor data. This intermediary processing layer reconciles the two data sources, using the inertial data to disambiguate acoustic signal sources and maintain accurate position estimates even when acoustic signal identification is uncertain due to reflections.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If traditional acoustic positioning methods are used, then positioning accuracy is maintained, but processing power requirements increase and update frequency decreases

Engineering Contradiction:

Improveposition estimate accuracyVSAvoidposition update frequency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces computationally intensive acoustic signal processing with lighter inertial sensor-based position tracking. The inertial measurement unit provides continuous position updates with minimal processing requirements, enabling high update frequencies while maintaining acceptable accuracy. This substitution is particularly beneficial for resource-constrained mobile devices.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental measurement parameters from acoustic signal characteristics (which require complex processing) to inertial sensor measurements (acceleration, rotation, magnetic field). This parameter change enables more frequent updates with reduced processing power while maintaining positioning functionality through fusion with occasional acoustic corrections.

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

Enables accurate position estimation of mobile devices even in environments with impaired communication, requiring less processing power and allowing more frequent updates than traditional methods, particularly beneficial for resource-constrained devices.

Implementation Method 1

transmitting acoustic signals from a plurality of acoustic transmitter units... The signals encode identifiers of the respective transmitters units. These signals are received by the mobile devices... the times at which a mobile device receives signals transmitted by the respective transmitter units (i.e. the times of arrival) can be used to estimate the position of the mobile device

Methodology Applied

Scientific EffectAcoustic signal propagation: Sound

Implementation Method 2

receive acceleration data, determined from an accelerometer of the mobile device, wherein the acceleration data is representative of acceleration of the mobile device due to a movement of the mobile device as it is carried by a person

Methodology Applied

Scientific EffectAcceleration measurement: Accelerometer

Data Source

PatentUS12474169B2Step-based positioning

Publication Date: 2025.11.18 SONITOR TECH AS

AI summary

In a positioning system (100) for estimating the position of a mobile device (7), a processing system (9) receives external-range data, representative of a range between the mobile device and an external unit (2, 3, 4, 5), and acceleration data representative of acceleration of the mobile device due to its movement as it is carried by a person (6). The acceleration data is processed in a step-detection algorithm to determine step-distance data representative of a time series of step-data-based distances travelled by the mobile device, and step-distance data is processed to determine a step-data-based position estimate for the mobile device. A position estimate for the mobile device is determined by solving an optimisation problem comprising a first cost term based on distance to positions located at said range from the external unit, and a second cost term based on distance to the step-data-based position estimate or to positions located at a step-data-based distance from said step-data-based position estimate.