Pedestrian Dead Reckoning Direction Calculation via Deceleration Vector
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Solution Overview
Problem
Existing pedestrian dead reckoning techniques face challenges in accurately calculating the advancement direction of a user due to high memory requirements, resource consumption, and difficulty in separating relevant acceleration components from unnecessary horizontal components, leading to inaccurate calculations.
Innovation Solution
An advancement direction calculation device equipped with an acceleration sensor that detects three-axis acceleration, a period specifying unit to identify stable deceleration periods, and a deceleration vector calculation unit to determine the advancement direction based on the deceleration vector in these periods, allowing for accurate determination of the user's movement direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor values of several steps are accumulated in a portable device to calculate advancement direction, then measurement precision is improved, but memory capacity requirement is tremendously increased
Solution Approach 1:
The patent extracts only the essential deceleration period information from the walking cycle using vertical acceleration changes, rather than accumulating and processing all sensor data. By identifying specific time periods where the foot lands (deceleration periods) through vertical acceleration peaks, the system calculates advancement direction from a minimal subset of data, dramatically reducing memory requirements while maintaining accuracy.
Solution Approach 2:
The walking cycle is segmented into distinct phases (deceleration period when foot lands, acceleration period when foot kicks off) based on vertical acceleration changes. By processing only the deceleration period data rather than the entire walking cycle, the system reduces the data volume needed for calculation while improving directional accuracy through focused analysis of the most informative segment.
2Measurement precision
If horizontal components related to walk are extracted from acceleration vectors, then advancement direction calculation is enabled, but separation from unnecessary horizontal components (body shake) becomes difficult
Solution Approach 1:
The patent uses vertical acceleration as an intermediary to identify the deceleration period, which then serves as a temporal marker for extracting horizontal acceleration components. By first detecting the foot landing event through vertical acceleration peaks, the system can then selectively process horizontal components only during the identified deceleration period, effectively separating relevant walk-related signals from body shake noise.
Solution Approach 2:
The system exploits the periodic nature of walking by identifying regular patterns in vertical acceleration (peaks corresponding to foot landings) to define deceleration periods. This periodic detection allows the system to consistently extract horizontal acceleration components at the correct phases of the walking cycle, improving separation accuracy between relevant and irrelevant signals.
3Measurement precision
If cloud service resources are increased to improve calculation accuracy, then measurement precision is improved, but resource consumption is greatly increased
Solution Approach 1:
The patent implements self-service by performing all advancement direction calculations locally on the portable device using simple processing of deceleration period data. The system independently identifies foot landing events through vertical acceleration and computes direction without requiring external cloud service assistance, eliminating resource consumption associated with cloud processing while maintaining high accuracy.
Data Source
AI summary
An advancement direction of a user who is walking is calculated with high accuracy. A period specifying unit specifies at least a part of a deceleration period, during which a horizontal component of acceleration is negative, as a stable deceleration period on the basis of a change of a vertical component of the acceleration, a deceleration vector calculation unit calculates a deceleration vector which indicates a deceleration direction in the stable deceleration period, and an advancement direction determination unit determines an advancement direction of a user on the basis of the deceleration vector.