Cadence detection based on inertial harmonics
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Publication Number
US-11363987-B2
Publication Date
2022-06-21
Expiration Date
Abstract
The method and apparatus disclosed herein determine a user cadence from the output of an inertial sensor mounted to or proximate the user's body. In general, the disclosed cadence measurement system determines the user cadence based on frequency measurements acquired from an inertial signal output by the inertial sensor. More particularly, a cadence measurement system determines a user cadence from an inertial signal generated by an inertial sensor, where the inertial signal comprises one or more frequency components. The cadence measurement system determines a peak frequency of the inertial signal, where the peak frequency corresponds to the frequency component of the inertial signal having the largest amplitude. After applying the peak frequency to one or more frequency threshold comparisons, the cadence measurement system determines the user cadence based on the peak frequency and the frequency threshold comparison(s).
Core Innovation
The invention relates to a wearable device configured to be worn by a subject. The device includes an inertial sensor that generates an inertial signal responsive to body motion of the subject, the inertial signal including a plurality of frequency components, and an optical emitter and an optical detector configured to generate a first output signal based on light scattered from or through skin of the subject. A processor circuit uses the inertial sensor and optical detector to determine a spectral signal from a frequency transform of the inertial signal and to determine a peak spectral signal having a peak frequency and a peak magnitude.
The processor circuit determines at least one frequency threshold responsive to a previous cadence of the subject and compares the peak frequency, corresponding to a frequency component of the inertial signal having a largest magnitude, to the at least one frequency threshold. The cadence of the subject is determined responsive to the comparison and responsive to the inertial signal and an inertial power threshold by comparing a power of the inertial signal to the inertial power threshold.
The device includes a noise circuit configured to attenuate motion artifact noise from the first output signal responsive to the determined cadence to generate a second output signal for output. The document further describes handling cadence harmonics using test cadences formed from fractions and multiples of a peak frequency, and selecting cadence determination rules based on frequency-threshold comparisons combined with inertial power thresholds to distinguish walking vs running/cycling and sprinting conditions.
Claims Coverage
The partial content contains two independent claims. The independent claims include inertial-signal spectral peak determination tied to frequency thresholds based on previous cadence, cadence determination combined with inertial power thresholding, and motion-artifact noise attenuation of an optical output signal.
Wearable inertial and optical device with peak spectral frequency cadence determination and cadence-conditioned motion-artifact attenuation
A device configured to be worn by a subject including an inertial sensor generating an inertial signal comprising a plurality of frequency components; an optical emitter and optical detector generating a first output signal from light interacting with skin; and at least one processor circuit determining a spectral signal from a frequency transform of the inertial signal, determining a peak spectral signal having a peak frequency corresponding to a frequency component of the inertial signal having a largest magnitude, determining at least one frequency threshold responsive to a previous cadence of the subject, comparing the peak frequency to the at least one frequency threshold, and determining a cadence of the subject responsive to the comparison; and a noise circuit configured to attenuate motion artifact noise from the first output signal responsive to the determined cadence to generate a second output signal for output.
Wearable inertial and optical device with frequency-threshold comparison and inertial power-threshold cadence determination plus motion-artifact attenuation
A device configured to be worn by a subject including an inertial sensor generating an inertial signal comprising a plurality of frequency components; an optical emitter and optical detector generating a first output signal from light interacting with skin; and at least one processor circuit determining at least one frequency threshold responsive to a previous cadence of the subject, comparing a peak frequency to the at least one frequency threshold, and determining, responsive to the comparison of the peak frequency and responsive to the inertial signal and an inertial power threshold, a cadence of the subject based on a comparison between a power of the inertial signal and the inertial power threshold; and a noise circuit configured to attenuate motion artifact noise from the first output signal responsive to the determined cadence to generate a second output signal for output.
Across the independent claims, the core claim coverage is directed to wearable cadence detection using an inertial sensor with spectral peak frequency determination compared against frequency thresholds based on previous cadence, combined with inertial power thresholding to determine cadence, and using the determined cadence to attenuate motion artifact noise from an optical detector output.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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