Pedestrian Dead Reckoning Gravity Axis Selection
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Solution Overview
Problem
Existing pedestrian dead reckoning technologies face challenges in accurately determining the traveling direction of a pedestrian carrying a mobile device, as they rely on sensor orientations and can result in erroneous direction determination due to varying mounting directions of acceleration sensors, limiting their effectiveness.
Innovation Solution
A traveling direction determination device and method that uses a triaxial acceleration sensor to select a gravity axis and a travel axis based on moving average values of acceleration signals, allowing for accurate direction determination irrespective of the sensor's mounting direction, by distinguishing between the gravity and travel axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional pedestrian dead reckoning technologies use sensor orientation and acceleration sensor output to determine traveling direction, then the system can function with basic sensors, but the traveling direction determination becomes erroneous when the acceleration sensor mounting direction varies
Solution Approach 1:
Instead of determining traveling direction directly from acceleration sensor output assuming a fixed mounting orientation, the invention inverts the approach by first determining the gravity axis (which is orientation-independent) and then using that as a reference to correctly interpret the acceleration sensor data. This inversion resolves the contradiction by making the system robust to mounting variations while maintaining accuracy.
Solution Approach 2:
The invention changes the reference parameter from assumed mounting orientation to dynamically determined gravity axis orientation. By using the gravity axis (determined from the acceleration component parallel to gravity) as the reference frame, the system adapts to any mounting direction, thereby maintaining measurement precision regardless of how the sensor is installed.
2Measurement precision
If the system uses complex sensor fusion algorithms involving multiple sensors and calculations to determine traveling direction, then directional accuracy may improve, but computational complexity and processing requirements increase
Solution Approach 1:
The invention extracts and utilizes only the essential component - the gravity axis determination from acceleration sensor data - to establish a reference frame. By taking out this key element and building the traveling direction determination around it, the system achieves good accuracy without requiring complex multi-sensor fusion algorithms, thus reducing computational complexity while maintaining precision.
3Device complexity
If the acceleration sensor is mounted in a fixed orientation assumption, then the calculation process is simple, but the system fails when the actual mounting direction differs from the assumed orientation
Solution Approach 1:
The invention makes the reference frame dynamic by continuously determining the gravity axis orientation from the acceleration sensor data itself, rather than relying on a fixed assumed orientation. This dynamic adaptation allows the system to automatically adjust to any mounting direction, significantly improving reliability while keeping the calculation process relatively simple through the use of moving average filtering.
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 enables simple and accurate determination of the traveling direction using only the output of an acceleration sensor, improving pedestrian positioning accuracy and reducing computational complexity compared to existing methods.
Implementation Method 1
uses an acceleration sensor that generates acceleration signals indicating acceleration in three axial directions together with a direction of the acceleration
Data Source
AI summary
Provided is a traveling direction determination device that determines, using an acceleration sensor that generates acceleration signals indicating acceleration in three axial directions together with a direction of the acceleration, a traveling direction of a moving object mounted with the acceleration sensor, the traveling direction determination device comprising a determination unit that executes a first determination process in which the determination unit selects, using the acceleration signals, any of the three axes as a gravity axis, the gravity axis being closest to an actual gravity direction of the moving object to determine a gravity direction of the moving object and a second determination process in which the determination unit selects either of the two axes excluding the axis selected as the gravity axis, as a travel axis, the travel axis being closest to an actual traveling direction of the moving object based on moving average values of the acceleration signals to determine the traveling direction of the moving object.