Step Measurement Device Using Dynamic Time Width Thresholds
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Solution Overview
Problem
Existing measurement devices for tracking steps taken by users through acceleration sensors face challenges in accurately differentiating between walking and running states due to reliance on amplitude of acceleration waveforms alone, leading to errors in step counting, especially in complex activities like running downstairs.
Innovation Solution
The device employs a combination of acceleration sensors, processors, and algorithms that analyze time-series acceleration data to determine reference ranges for time widths of partial waveforms, considering both amplitude and first piece count, to accurately discriminate between walking and running states and adjust threshold values accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If amplitude of acceleration waveform is used to determine user state and time width threshold, then device complexity is reduced, but measurement precision deteriorates due to inability to accurately differentiate between walking and running states in complex activities
Solution Approach 1:
The patent changes the determination parameters from relying solely on amplitude to using a combination of amplitude and time width parameters. By dynamically adjusting the time width threshold based on amplitude values, the system achieves more accurate state differentiation without significantly increasing device complexity. The processor calculates time width between zero-crossing points and compares it against amplitude-based thresholds to determine walking vs. running states.
2Ease of operation
If simple amplitude-based threshold is used for time width determination, then ease of operation is improved, but measurement precision deteriorates leading to errors in complex activities like running downstairs
Solution Approach 1:
The patent implements dynamic threshold adjustment where the time width threshold is not fixed but varies based on the measured amplitude of acceleration waveform. The system calculates amplitude values and corresponding time width thresholds dynamically, allowing the measurement criteria to adapt to different activity intensities and types. This dynamic approach maintains ease of operation while significantly improving measurement precision in complex activities.
3Device complexity
If fixed time width threshold is used regardless of user state, then device complexity is reduced, but measurement precision deteriorates due to inability to adapt to different walking and running characteristics
Solution Approach 1:
The system changes from a fixed threshold parameter to a dynamic parameter that varies with amplitude measurements. The processor determines time width thresholds based on the relationship between amplitude values and temporal characteristics of acceleration waveforms. This parameter adaptation allows accurate discrimination between walking and running states without requiring complex machine learning models or multiple sensors.
Data Source
AI summary
A measurement device includes an acceleration sensor, a memory, and one or more processors that follow instructions saved in the memory to execute following processing of: acquiring time-series acceleration data output by the acceleration sensor; specifying, based on the acquired time-series acceleration data, first and second timing at which acceleration goes above and below an acceleration reference value; determining a reference range for a time width from the first to second timing based on amplitude of an acceleration waveform corresponding to the time-series acceleration data and a first piece count of at least either the first or second timing within predetermined time; determining whether the time width falls within the determined reference range; and counting one step for a partial waveform from the first to second timing in the acceleration waveform when the time width is determined as falling within the reference range.