Pedestrian Dead Reckoning Direction Calculation Using Acceleration Sensor
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Solution Overview
Problem
Existing pedestrian dead reckoning (PDR) systems struggle to accurately discriminate between walking and running and detect traveling direction with high accuracy, especially when GPS signals are unavailable, due to limitations in existing technologies that rely on gyro sensors, magnetic field sensors, and acceleration sensors.
Innovation Solution
A traveling direction calculation apparatus equipped with an acceleration sensor, a period identification unit, an action determination unit, and a vector calculator, which identifies stable measurement periods and idling leg periods based on vertical acceleration components to differentiate between walking and running, and calculates velocity vectors from horizontal acceleration components to determine the traveling direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency analysis is used to determine traveling direction from acceleration sensor data, then traveling direction can be detected, but memory space and computational resources are considerably increased
Solution Approach 1:
The patent extracts only the essential features needed for action recognition (vertical acceleration patterns during specific gait phases) rather than performing comprehensive frequency analysis on all acceleration data. This selective extraction of critical information reduces computational burden and memory requirements while maintaining accurate discrimination between walking and running.
Solution Approach 2:
The patent segments the gait cycle into distinct phases (stable measurement period and idling leg period) and analyzes acceleration characteristics separately for each phase. By dividing the continuous acceleration data into discrete, meaningful segments, the system achieves accurate action recognition without requiring resource-intensive continuous frequency analysis.
2Measurement precision
If gyro sensor and magnetic field sensor are used to calculate traveling direction, then turning angle can be calculated, but lateral steps and other movements are not detected
Solution Approach 1:
The patent makes the acceleration sensor serve multiple functions: it detects both forward motion (through horizontal acceleration integration) and action type (through vertical acceleration pattern recognition). This multi-functional use of a single sensor replaces the need for separate gyro and magnetic field sensors, enabling detection of all movement types including lateral steps while reducing device complexity.
3Measurement precision
If all acceleration data items are used to obtain distribution for direction estimation, then statistical analysis can be performed, but directions related to running and walking are not discriminated
Solution Approach 1:
The patent applies different analysis methods to different portions of the acceleration data based on the gait phase. Vertical acceleration during the idling leg period is used specifically for action discrimination, while horizontal acceleration during the stable measurement period is used for direction calculation. This localized, phase-specific analysis preserves the distinctive characteristics of running versus walking that would be lost in overall statistical distribution.
Data Source
AI summary
A travelling direction calculation apparatus includes an acceleration sensor, a period identification unit, an action determination unit, a vector calculator, and a travelling direction decision unit. The period identification unit identifies a stable measurement period and an idling leg period based on change in a vertical component of acceleration detected by the acceleration sensor. The action determination unit discriminates between walking and running by using the minimum value of the vertical component of the acceleration in the idling leg period. The vector calculator calculates a velocity vector from a horizontal component of the acceleration in the stable measurement period. The travelling direction decision unit decides a direction of traveling of a user based on a result of determination performed by the action determination unit and the velocity vector calculated by the vector calculator.