Inertial Navigation Walk Detection via Angular Velocity Filtering
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Solution Overview
Problem
Inertial positioning devices face accuracy issues with walk detection and error accumulation, particularly when the device is rotated or shaken, leading to misidentification of the user's walk state and displacement estimation.
Innovation Solution
A novel walk detection method using an inertial measurement unit (IMU) that measures triaxial components of gravitational acceleration, calculates triaxial angular velocity, filters data, and compares differences with thresholds to determine the user's motion state, distinguishing between walking and shaking states, thereby improving displacement vector calculation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If inertial positioning device uses IMU to detect walk state, then positioning can be performed without infrastructure, but walk detection accuracy deteriorates when device is rotated or shaken
Solution Approach 1:
The patent introduces an intermediary processing mechanism that separates the raw IMU signals into two independent detection channels: one for detecting walk state through angular velocity patterns, and another for detecting shake state through acceleration variations. This intermediary processing layer resolves the contradiction by enabling the system to distinguish between legitimate walk movements and shake disturbances, thereby maintaining high measurement precision while preserving the infrastructure-free positioning capability.
Solution Approach 2:
The patent segments the motion detection task into distinct functional modules: a walk detection module that analyzes angular velocity for walking patterns, and a shake detection module that monitors acceleration for shake states. This segmentation allows each module to specialize in detecting specific motion characteristics, improving overall detection accuracy without compromising the portability and versatility of the positioning system.
2Ease of operation
If inertial positioning device continuously tracks displacement, then navigation is enabled, but error accumulation increases
Solution Approach 1:
The patent implements a feedback mechanism where the shake detection module continuously monitors the device's motion characteristics and provides real-time feedback to the walk detection module. When shake states are detected, the system adjusts its displacement calculation parameters or pauses accumulation, preventing error propagation. This feedback loop maintains navigation capability while significantly reducing error accumulation over time.
Solution Approach 2:
The patent performs preliminary detection and classification of motion states before initiating displacement accumulation. By pre-identifying whether the device is in a walk state, shake state, or stationary state, the system can selectively activate displacement tracking only when appropriate, preventing erroneous accumulation during shake or stationary periods while maintaining continuous navigation during valid walk detections.
3Device complexity
If device uses threshold-based walk detection, then processing is simple, but misdetection occurs during rotation or shaking
Solution Approach 1:
The patent transforms the static threshold-based detection into a dynamic multi-parameter evaluation system. Instead of relying on a single fixed threshold, the system dynamically adjusts detection criteria based on real-time analysis of both angular velocity and acceleration patterns. This dynamic approach maintains processing simplicity through automated pattern recognition while significantly improving walk state identification accuracy during complex motion scenarios like rotation and shaking.
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 method accurately detects the user's walk state and generates precise displacement vectors, enhancing navigation without relying on positioning infrastructure, reducing electromagnetic interference and infrastructure costs.
Implementation Method 1
measuring, by the IMU 110, the triaxial components of gravitational acceleration vector of the device worn on the user
Implementation Method 2
calculating, by the displacement processing unit 120, the triaxial angular velocity of the device via the triaxial components of gravitational acceleration vector detected in step a) and kinematics
Data Source
AI summary
A walk detection method for detecting a motion state of a user includes: measuring a number of triaxial components of gravitational acceleration vector of the device; calculating a triaxial angular velocity of the device; recording data inputs of the triaxial angular velocity, and recording the data inputs not larger than a filtered threshold as effective data inputs; calculating a mean of effective data inputs; calculating a difference value between the effective data inputs and a mean thereof; and determining that, when the difference value is smaller than a threshold of walking state, the user is in a walking state. Otherwise, the user is determined to be in a shaking state at the same location.