Pedestrian Vehicle Mode Detection via Inertial Sensor

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Solution Overview

Problem

Existing navigation systems face challenges in accurately distinguishing between pedestrian and road navigation modes, especially in urban environments with multi-path signal reception and low-speed traffic congestion, leading to incorrect mode selection and false guidance.

Innovation Solution

A portable device uses an inertial sensor to differentiate between pedestrian and road modes by analyzing the frequency band power spectrum density of inertial sensor excitations, with low frequencies indicating pedestrian mode and high frequencies indicating road mode, employing threshold comparisons and a delay timer to stabilize mode switching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If GNSS switches between pedestrian mode and road mode based on speed, then mode selection is automated, but incorrect mode selection occurs in urban environments with traffic congestion where vehicle speeds resemble pedestrian speeds

Engineering Contradiction:

Improveautomated mode selectionVSAvoidmode selection accuracy

Core Design Contradiction:

Extent of automationVSReliability

Solution Approach 1:

The patent replaces speed-based mode selection with acceleration-based mode selection using an inertial sensor. Instead of relying on GNSS speed calculations which are inaccurate in urban environments, the system uses the accelerometer to detect characteristic acceleration patterns that distinguish pedestrian movement from vehicle movement, eliminating the fundamental limitation of speed-based detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from speed to acceleration characteristics. By analyzing acceleration magnitude, direction changes, and temporal patterns rather than linear speed, the system can reliably distinguish between pedestrian and vehicle modes even when speeds are similar, as the acceleration profiles of these two modes are fundamentally different.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If GNSS relies on satellite signal reception to determine position, then position can be calculated, but multi-path signal reflection in urban environments causes position errors leading to incorrect mode selection

Engineering Contradiction:

Improveposition accuracyVSAvoidmulti-path signal error

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an inertial sensor as an intermediary measurement system to complement GNSS. The accelerometer provides independent motion detection that is not affected by satellite signal reflections. By fusing inertial measurement data with GNSS position data, the system can detect when GNSS position errors occur and use inertial data to correct or override incorrect mode selections.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses feedback from the inertial sensor to continuously monitor and validate GNSS-derived position and speed data. When the inertial sensor detects acceleration patterns inconsistent with the current mode (e.g., vehicle-like accelerations during pedestrian mode), it triggers mode re-evaluation, creating a feedback loop that corrects errors caused by multi-path signaling.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If the device uses accelerometer signals to distinguish pedestrian and road modes, then mode differentiation is possible, but device handling in vehicles generates signals similar to pedestrian mode causing incorrect switching

Engineering Contradiction:

Improveautomatic mode detectionVSAvoidmode detection accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies local quality analysis by examining specific temporal and spectral characteristics of acceleration signals rather than overall signal magnitude. It analyzes the frequency spectrum of accelerometer data, focusing on characteristic frequency ranges that distinguish pedestrian gait patterns from vehicle vibrations and handling motions, enabling accurate mode detection despite similar overall signal intensities.

Inventive Principle:

Principle #3Local quality

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

The system effectively distinguishes between pedestrian and road navigation modes, even in challenging environments, reducing incorrect mode selection and providing accurate navigation instructions, while maintaining a constant processor load.

Implementation Method 1

a portable mobile device incorporating a global navigation satellite system receiver and an inertial sensor

Methodology Applied

Scientific EffectInertial sensing: Accelerometer

Data Source

PatentEP2762834B1An integrated global navigation satellite system and inertial navigation system

Publication Date: 2017.03.22 INTEL CORP

AI summary

A cell phone (1) or similar portable device includes a global navigation satellite subsystem (5) and an inertial navigation subsystem (7) responsive to an inertial sensor (6). The inertial sensor (6) is used in a navigation mode discrimination routine to sample the frequency of inertial disturbances of the device and the sampled frequencies are processed to determine if the device is being carried by a pedestrian or carried in a vehicle. By reliably determining the mode of transport, erroneous navigation can be avoided.