Mobile Device Step Count Compensation for Arm Swing
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Solution Overview
Problem
Mobile devices struggle to accurately count steps when worn on the arm due to interference from arm swing movements, which can lead to inaccurate step detection using existing threshold crossing and frequency analysis methods.
Innovation Solution
The mobile device transforms motion signals from a time domain to a frequency domain, identifies dominant and harmonic peaks within a pedestrian frequency band, and adjusts the step count by compensating for arm swing interference by multiplying the preliminary step count if the dominant frequency corresponds to the arm swing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the mobile device uses threshold crossing or frequency analysis methods to detect steps, then step counting functionality is provided, but arm swing movements cause inaccurate step detection
Solution Approach 1:
The patent segments the frequency spectrum into distinct bands (pedestrian frequency band for steps, arm swing frequency band for arm movements). By separating these frequency components, the system can independently analyze and count steps without interference from arm swing signals, thus resolving the accuracy issue while maintaining step counting functionality.
2Ease of operation
If the mobile device is worn on the arm for convenient step tracking, then ease of use is improved, but arm swing interference degrades measurement accuracy
Solution Approach 1:
The patent converts the harmful arm swing signal into a beneficial component by identifying its characteristic frequency band and using it as a reference. The system detects arm swing frequency and uses this information to adjust or filter the step detection algorithm, thereby compensating for the interference and improving measurement accuracy while keeping the device worn on the arm.
3Measurement precision
If frequency analysis is used to identify step frequency, then step detection is enabled, but arm swing frequency interferes with accurate identification
Solution Approach 1:
The patent introduces a frequency domain dimension to distinguish between step signals and arm swing signals. By transforming the time-domain acceleration signal into the frequency domain and analyzing spectral components, the system can differentiate between the two types of movements based on their characteristic frequencies, thereby eliminating interference while maintaining accurate step frequency identification.
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 ensures accurate step counting by distinguishing between step and arm swing frequencies, providing a corrected step count that is not affected by arm movement when the device is worn on the arm, thus improving the reliability of step tracking.
Implementation Method 1
The mobile device can transform the motion signal from a time domain signal into a frequency domain signal
Data Source
AI summary
In some implementations, a mobile device can receive a motion signal from a motion sensor on the mobile device. The mobile device can determine a step count based on the motion signal. The mobile device can transform the motion signal from a time domain signal into a frequency domain signal. The mobile device can determine a dominant peak and harmonic peaks of the motion signal within a pedestrian frequency band. The mobile device can determine that the dominant peak corresponds to an arm swing of a user and adjust the step count to compensate for the arm swing.