Pedometer Arm Swing Noise Filtering via Band-Pass Signal Segmentation
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Solution Overview
Problem
Conventional pedometers worn on the arm inaccurately measure steps due to acceleration signals being affected by arm swinging motions, leading to errors in counting.
Innovation Solution
Incorporation of two band-pass filters that remove frequency components associated with arm swinging during walking and running, allowing the pedometer to isolate and count only the walking or running components of the acceleration signal, using a configuration that includes an acceleration sensor, band-pass filters, step counters, and a control unit to differentiate between walking and running.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pedometer is worn on the arm for ease of operation, then the pedometer is more convenient to wear, but the measurement precision deteriorates due to arm swinging motion interference
Solution Approach 1:
The acceleration signal is segmented by frequency components using band-pass filters. The filter separates the arm swinging frequency component from the walking/running frequency component, allowing independent processing of each motion type to resolve the measurement accuracy issue while maintaining arm-wearing convenience
Solution Approach 2:
The system changes the parameter of frequency selection by adjusting band-pass filter characteristics. By changing the center frequency and bandwidth of the filter based on detected motion patterns, the system can selectively amplify walking/running signals while suppressing arm swinging signals, thereby improving measurement precision without changing the wearing position
2Productivity
If the pedometer uses acceleration sensor to detect walking motion, then the pedometer can measure steps, but the measurement precision deteriorates when worn on arm due to interference from arm swinging acceleration
Solution Approach 1:
The harmful arm swinging frequency component is extracted and removed from the acceleration signal using band-pass filtering. By taking out the interfering frequency component and retaining only the walking/running frequency component, the system maintains step counting functionality while eliminating the source of measurement errors
Solution Approach 2:
The band-pass filter acts as an intermediary between the acceleration sensor and the step counting logic. It mediates the signal by selectively passing desired frequency components while attenuating unwanted ones, thereby enabling accurate step detection despite the presence of arm swinging interference
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
The solution enables accurate step counting on the arm, with the pedometer accurately measuring steps without being influenced by arm movements, as demonstrated by a significant reduction in error compared to conventional pedometers, with the pedometer accurately tracking both walking and running steps.
Implementation Method 1
an acceleration sensor which detects acceleration in one or more directions and outputs an acceleration signal
Implementation Method 2
a first band-pass filter configured to remove, from the acceleration signal, a frequency component generated by arm swinging during walking and included in the acceleration signal
Data Source
AI summary
According to an embodiment, a pedometer includes an acceleration detecting circuit configured to detect acceleration from an output of an acceleration sensor and output an acceleration signal, a band-pass filter configured to remove, from the acceleration signal, a frequency component generated by arm swinging during walking and included in the acceleration signal, and a step counter configured to count a number of steps based on the acceleration signal outputted from the band-pass filter.