Pedestrian Dead Reckoning Heading via Accelerometer Pattern Matching

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Solution Overview

Problem

Conventional mobile devices struggle to accurately determine the walking direction of a user, as the heading provided by a digital compass does not align with the user's actual movement direction, especially when the device is held by a person walking, and existing techniques using MEMS magnetic sensors and accelerometers are not effective in all scenarios.

Innovation Solution

The method employs MEMS inertial sensors to collect accelerometer data, processes it to determine the walking angle by pattern matching with reference patterns, and adjusts parameters to predict the walking angle accurately, even when the device placement position is unknown, using a combination of pattern matching and dynamic time warping techniques to account for individual variations in walking patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a digital compass is used to provide heading, then the device heading is obtained, but it does not align with the user's actual walking direction

Engineering Contradiction:

Improveheading accuracyVSAvoidapplicability to walking scenarios

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces the magnetic field-based digital compass with an inertial measurement system using MEMS accelerometers and gyroscopes to determine walking direction. This mechanical substitution allows the system to calculate heading based on motion dynamics rather than magnetic orientation, resolving the mismatch between device heading and user walking direction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system dynamically changes parameters including sampling frequency, integration time constants, and filter coefficients based on detected walking states. By adjusting these parameters in real-time according to motion characteristics, the system achieves accurate heading determination adapted to various walking scenarios.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If tilt compensated heading techniques are used, then device orientation is corrected, but it remains ineffective for pedestrian walking applications

Engineering Contradiction:

Improveheading compensation accuracyVSAvoidsuitability for ambulatory motion

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic pedestrian dead reckoning system that continuously adapts to changing walking conditions. The system uses real-time accelerometer and gyroscope data to dynamically calculate heading, contrasting with static tilt compensation methods. This dynamic approach enables accurate heading determination during ambulatory motion by continuously updating based on motion patterns.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system incorporates feedback mechanisms where detected walking motion characteristics are fed back into the heading calculation algorithm. The accelerometer and gyroscope measurements provide continuous feedback about device orientation and motion state, allowing the system to adjust and refine heading estimates in real-time during pedestrian movement.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If pattern matching with reference patterns is implemented, then individual walking variations are accounted for, but computational complexity increases

Engineering Contradiction:

Improvewalking angle determination accuracyVSAvoidprocessing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent performs preliminary actions by pre-processing accelerometer data to extract walking pattern features and creating reference patterns before final heading calculation. This preliminary pattern extraction and comparison approach simplifies the main computation by reducing raw data to essential characteristics, thereby managing computational complexity while maintaining accuracy.

Inventive Principle:

Principle #10Preliminary action

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 allows for accurate determination of the walking direction, improving navigation accuracy by dynamically adjusting to the user's specific walking context and device placement, enhancing the reliability of position determination in ambulatory motion scenarios.

Implementation Method 1

collecting accelerometer data in a device associated with a person while the person is walking

Methodology Applied

Scientific EffectAccelerometer: Accelerometer

Implementation Method 2

collecting gyroscope data in the device while the person is walking

Methodology Applied

Scientific EffectGyroscope: Gyroscope

Implementation Method 3

collecting magnetometer data in the device while the person is walking

Methodology Applied

Scientific EffectMagnetometer: Magnetometer

Data Source

PatentUS10302434B2Method and apparatus for determining walking direction for a pedestrian dead reckoning process

Publication Date: 2019.05.28 QUALCOMM INC

AI summary

The present invention relates generally to position determination, and more particularly to methods and apparatuses to determine the walking direction (heading of a user) using MEMS inertial sensors commonly found in mobile devices such as cellphones. According to some aspects, the invention includes a methodology to allow the walking angle to be determined dynamically. In embodiments, the methodology includes pattern matching accelerometer measurement data to a reference acceleration pattern.