Calibrating Accelerometer Stride Length Using Map Data
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Solution Overview
Problem
Existing activity monitoring systems face challenges in accurately calibrating distance measurements, particularly in areas with obstructed GPS signals and failure to account for altitude changes and physiological parameters, leading to inaccuracies in distance tracking.
Innovation Solution
A method and system that utilize map data to identify a calibration route with a known length, allowing users to collect step data using an accelerometer, and calculate a calibration factor based on this data to accurately determine physiological parameters such as stride length, thereby calibrating distance measurements without relying on GPS signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS calibration is used to determine distance, then calibration can be performed using readily available GPS signals, but GPS signals are blocked in urban canyon environments leading to inaccurate calibration
Solution Approach 1:
The patent introduces map data as an intermediary to replace GPS signals for calibration. Instead of relying on GPS to provide distance information, the system uses pre-stored map data containing known route lengths as a mediator to enable calibration when GPS is unavailable, thus resolving the contradiction between calibration reliability and GPS signal availability
Solution Approach 2:
The patent changes the calibration parameter source from GPS-derived distance to map data-derived known route length. By switching the reference parameter from satellite-based positioning to pre-mapped route information, the system maintains calibration accuracy in environments where GPS signals are blocked
2Ease of operation
If standard GPS calibration is used, then the calibration process is simple and straightforward, but it does not account for altitude changes and physiological parameters affecting stride length
Solution Approach 1:
The patent performs preliminary actions by pre-storing map data with known route lengths and elevation information before calibration is needed. This allows the system to have calibration reference data ready in advance, maintaining operational simplicity while enabling more accurate calibration that accounts for altitude changes and route-specific characteristics
Solution Approach 2:
The patent adds the elevation/altitude dimension to the calibration process. By incorporating vertical elevation changes from map data alongside horizontal distance, the system creates a three-dimensional calibration model that accounts for altitude effects on stride length, improving measurement precision without significantly complicating the user experience
3Productivity
If accelerometer data is processed without calibration, then distance can be estimated quickly, but the distance measurement lacks accuracy due to user-specific physiological variations
Solution Approach 1:
The patent implements feedback by using the known route length from map data to calculate a calibration factor that adjusts the accelerometer-based distance estimates. The system measures actual performance against the known reference and uses this feedback to refine future distance calculations, maintaining speed while improving accuracy through user-specific calibration
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 provides accurate and reliable distance tracking by accounting for user-specific physiological parameters and environmental factors, improving the precision of activity monitoring systems in various environments.
Implementation Method 1
One type of measuring device comprises an activity or distance measuring device which includes an accelerometer for determining the distance traversed by the runner. The accelerometer generates accelerometer data based on the detected movements associated with each stride taken by the runner.
Data Source
AI summary
Apparatus and method for using map data of a known route to calibrate an accelerometer to one or more physiological parameters of a user. In one embodiment, the calibration comprises determining a current position of a user; consulting map data to identify a route having a starting and/or ending position within a predefined proximity to the current position, the route having a known length; collecting data with the accelerometer as the user traverses the route; calculating a calibration factor based on one or more physiological qualities specific to the user; and causing the calibration factor to be stored and applied to subsequently collected data from the accelerometer.