Signal detection device and signal detection method

• US 10,426,408 B2
• Filed: 02/16/2017
• Issued: 10/01/2019
• Est. Priority Date: 08/26/2015
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Nakanishi, Masahiro, Hirose, Yoshifumi, Araki, Shoichi
• Primary Examiner(s): Bloss, Stephanie E
• Assistant Examiner(s): Islam, Mohammad K
• Application Number:
  US15/434,582
• Publication Number:
  US 20170156677A1
• Time in Patent Office: 957 Days
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/2415 Measuring direct current [DC] or slowly varying biopotentials
• CPC Class Codes: A61B 5/332 Portable devices specially adapted therefor
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/6804 Garments; Clothes
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F

Abstract

A signal detection device includes a measurer, an arithmetic operation unit, and signal period detector, and detects information such as a cardiac cycle with high accuracy by causing resonance of only a signal such as a heartbeat, the signal having strong pulse characteristics. The measurer measures a signal. The arithmetic operation unit performs nonlinear arithmetic operation processing for amplifying a pulse-like component of the signal measured by the measurer and suppressing a component other than the pulse-like component of the signal measured by the measurer. The signal period detector detects a periodic signal from an output of the arithmetic operation unit.

Claims

1. A signal detection device comprising:

a measurer that measures an electrocardiogram signal of a subject;

an arithmetic operation unit that receives the electrocardiogram signal, performs nonlinear arithmetic operation processing on the electrocardiogram signal for amplifying a pulse-like component of the electrocardiogram signal and suppressing a component other than the pulse-like component of the electrocardiogram signals and outputs an output signal of the nonlinear arithmetic operation processing; and

a signal period detector that detects a periodic signal and a frequency of the periodic signal from the output signal of the arithmetic operation unit, wherein;

the arithmetic operation unit selects a time difference term of the nonlinear arithmetic operation processing, based on the frequency of the periodic signal, and

the arithmetic operation unit detects a cardiac cycle of the subject by performing the nonlinear arithmetic operation processing on the electrocardiogram signal with the selected time difference term;

wherein the nonlinear arithmetic operation processing is arithmetically operated based on an input variable corresponding to an input of the nonlinear arithmetic operation processing and based on an output variable corresponding to an output of the nonlinear arithmetic operation processing,

when the input variable is constant at a first value, the output variable becomes a self-oscillation waveform, which is a periodic waveform,

when the input variable is constant at a second value, the output variable becomes a constant value,

when the input variable is a waveform mainly containing a periodic pulse-like component, the output variable becomes a resonating signal waveform, and

a period of the resonating signal waveform is equal to a period of the waveform mainly containing the periodic pulse-like component.

2. The signal detection device according to claim 1, wherein

the arithmetic operation unit performs the nonlinear arithmetic operation processing after performing direct current (DC) removal for the electrocardiogram signal measured by the measurer.

3. The signal detection device according to claim 1, wherein the signal period detector detects the periodic signal by detecting a point of time when the resonating signal waveform intersects a predetermined detection threshold value.

4. The signal detection device according to claim 1, wherein

the arithmetic operation unit performs the nonlinear arithmetic operation processing a plurality of times.

5. The signal detection device according to claim 1, wherein

the nonlinear arithmetic operation processing is performed by using a FitzHugh-Nagumo equation.

6. The signal detection device according to claim 1, wherein

the nonlinear arithmetic operation processing is performed by a following expression:

7. The signal detection device according to claim 1, wherein

the periodic signal is a cycle of a heartbeat.

8. A signal detection method performed by a signal detection device, the signal detection method comprising:

measuring an electrocardiogram signal of a subject;

performing nonlinear arithmetic operation processing on the electrocardiogram signal for amplifying a pulse-like component of the electrocardiogram signal and suppressing a component other than the pulse-like component of the electrocardiogram signal and outputting an output signal of the nonlinear arithmetic operation processing;

detecting a periodic signal and a frequency of the periodic signal from the output signal of the nonlinear arithmetic operation processing;

setting selecting a time difference term of the nonlinear arithmetic operation processing, based on the frequency of the periodic signal; and

detecting a cardiac cycle of the subject by performing the nonlinear arithmetic operation processing with the selected time difference term;

wherein the nonlinear arithmetic operation processing is arithmetically operated based on an input variable corresponding to an input of the nonlinear arithmetic operation processing and based on an output variable corresponding to an output of the nonlinear arithmetic operation processing,

when the input variable is constant at a first value, the output variable becomes a self-oscillation waveform, which is a periodic waveform,

when the input variable is constant at a second value, the output variable becomes a constant value,

when the input variable is a waveform mainly containing a periodic pulse-like component, the output variable becomes a resonating signal waveform, and

a period of the resonating signal waveform is equal to a period of the waveform mainly containing the periodic pulse-like component.

9. The signal detection method according to claim 8, wherein

the electrocardiogram signal is subjected to direct current (DC) removal before the nonlinear arithmetic operation processing is performed.

10. The signal detection method according to claim 8, wherein:

the nonlinear arithmetic operation processing is arithmetically operated based on an input variable corresponding to an input of the nonlinear arithmetic operation processing and based on an output variable corresponding to an output of the nonlinear arithmetic operation processing,

when the input variable is constant at a first value, the output variable becomes a self-oscillation waveform, which is a periodic waveform,

when the input variable is constant at a second value, the output variable becomes a constant value,

when the input variable is a waveform mainly containing a periodic pulse-like component, the output variable becomes a resonating signal waveform, and

a period of the resonating signal waveform is equal to the period of the waveform mainly containing the periodic pulse-like component.

11. The signal detection method according to claim 10, wherein

the periodic signal is detected by detecting a point of time when the resonating signal waveform intersects a predetermined detection threshold value.

12. The signal detection method according to claim 8, wherein

the nonlinear arithmetic operation processing is performed a plurality of times.

13. The signal detection method according to claim 8, wherein

the nonlinear arithmetic operation processing is performed by using a FitzHugh-Nagumo equation.

14. The signal detection method according to claim 8, wherein

the nonlinear arithmetic operation processing is performed by a following expression:

15. The signal detection method according to claim 8, wherein

the periodic signal is a cycle of a heartbeat.

16. A method of detecting a cardiac cycle of a subject, the method comprising:

obtaining an electrocardiogram signal of the subject;

generating a first processed signal by performing nonlinear arithmetic operation processing on the electrocardiogram signal with an initial time difference term;

detecting a first periodic signal from the first processed signal and detecting a first frequency of the first periodic signal;

determining a new time difference term based on the first frequency; and

detecting the cardiac cycle of the subject by performing the nonlinear arithmetic operation processing on the electrocardiogram signal with the new time difference term;

wherein the nonlinear arithmetic operation processing is arithmetically operated based on an input variable corresponding to an input of the nonlinear arithmetic operation processing and based on an output variable corresponding to an output of the nonlinear arithmetic operation processing,

when the input variable is constant at a first value, the output variable becomes a self-oscillation waveform, which is a periodic waveform,

when the input variable is constant at a second value, the output variable becomes a constant value,

when the input variable is a waveform mainly containing a periodic pulse-like component, the output variable becomes a resonating signal waveform, and

a period of the resonating signal waveform is equal to a period of the waveform mainly containing the periodic pulse-like component.

17. The method according to claim 16, further comprising:

generating a second processed signal by performing the nonlinear arithmetic operation processing on the electrocardiogram signal with the new time difference term;

detecting a second periodic signal from the second processed signal; and

detecting a second frequency of the second periodic signal as the cardiac cycle of the subject.

18. The method according to claim 16, further comprising measuring the electrocardiogram signal of the subject.

19. The method according to claim 16, wherein renewal of the time difference term and performing the nonlinear arithmetic operation processing are repeated.