Pedometer Calibration via GPS-Stride Weighted Averaging
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Solution Overview
Problem
Electronic pedometers face challenges in accurately determining distance traveled due to difficulties in measuring stride length, which can change over time, and varying accuracy based on pedometer placement on the body, leading to unreliable performance data.
Innovation Solution
The development of electronic pedometer devices that can be calibrated transparently using other pedometer devices, with automatic selection of calibration tracks based on sustained locomotion activities, utilizing GPS technology to determine distance and combining data for accurate stride length measurements through weighted averaging techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stride length is measured directly by user input, then the pedometer can convert step count to distance, but the measurement accuracy deteriorates because users find it difficult to measure accurately and stride length changes over time
Solution Approach 1:
The pedometer automatically performs calibration without requiring user intervention. The device detects sustained locomotion activities, collects step count and location data automatically, and computes calibration parameters autonomously, eliminating the need for users to manually measure and input stride length
Solution Approach 2:
The system uses GPS location data as a reference to feedback and adjust the calibration parameters. By comparing the distance calculated from step count with the actual GPS-tracked distance, the system automatically refines stride length measurements and improves accuracy over time
2Ease of operation
If pedometer is worn on different body locations, then user convenience is improved, but measurement accuracy deteriorates due to varying degrees of inaccuracy
Solution Approach 1:
The system creates separate calibration parameters for different body locations where the pedometer may be worn. By detecting the wear location and applying location-specific calibration data, the system maintains high measurement accuracy regardless of where the device is placed on the user's body
Solution Approach 2:
The calibration parameters (such as stride length and conversion factors) are adjusted based on the detected wear location. The system dynamically changes these parameters to compensate for the different motion characteristics associated with wearing the device on different parts of the body
3Measurement precision
If GPS receiver is activated continuously for calibration, then calibration accuracy is improved, but energy consumption increases
Solution Approach 1:
The GPS receiver is activated periodically only during detected sustained locomotion activities rather than continuously. The system monitors motion sensors to identify appropriate calibration opportunities, activates GPS only during these periods to collect calibration data, then deactivates it, significantly reducing overall power consumption while maintaining calibration accuracy
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 solution provides accurate and reliable distance calculations by automatically calibrating pedometer devices during sustained activities, improving the accuracy of step count and distance measurements regardless of pedometer placement, and allowing for separate calibration settings for different activities and body locations.
Implementation Method 1
a pedometer device can activate a GPS receiver (or other location-determining technology), which can be internal or external to the pedometer device, to track the user's location
Implementation Method 2
pedometry data (e.g., accelerometer data) to determine steps or strides
Data Source
AI summary
A calibration track to use for pedometer calibration can be automatically selected based on detecting sustained locomotion activity and an ability to obtain and maintain a reliable location fix over a calibration period. Calibration tracks can be generated, rated for quality, and used to compute calibration parameters to convert accelerometer data to stride length and/or distance traveled. Quality of a calibration can be assessed, and old and new calibration parameter sets can be combined based on quality weights assigned to each. Calibration parameters can be separately maintained for different locomotion activities and/or different on-body locations of the pedometers. Pedometer devices can also cooperatively calibrate each other.