HEART MONITORS AND PROCESSES WITH ACCELEROMETER MOTION ARTIFACT CANCELLATION, AND OTHER ELECTRONIC SYSTEMS

• US 20110098583A1
• Filed: 08/24/2010
• Published: 04/28/2011
• Est. Priority Date: 09/15/2009
• Status: Abandoned Application

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Cole, Edwin Randolph, Ravindran, Sourabh, Pandia, Keya R.
• Application Number:
  US12/861,874
• Publication Number:
  US 20110098583A1
• Time in Patent Office: Days
• US Class Current: 600/508
• CPC Class Codes: A61B 2505/07 Home care
• CPC Class Codes: A61B 2560/0475 Special features of memory means, e.g. removable memory cards
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/1102 Ballistocardiography
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61B 7/008 Detecting noise of gastric tract, e.g. caused by voiding

Abstract

A heart monitor includes a single chest accelerometer (210), an analog signal conditioning and sampling section (215) responsive to said accelerometer to produce a digital signal substantially representing acceleration, and a digital processor (220) operable to filter the acceleration signal into a signal affected by body motion and to cancel the body motion signal from the acceleration signal, thereby to produce an acceleration-based cardiac-related signal. Other processes and electronic systems are also disclosed.

Claims

1. A heart monitor comprising:

a single chest accelerometer;

an analog signal conditioning and sampling section responsive to said accelerometer to produce a digital signal substantially representing acceleration; and

a digital processor operable to filter the acceleration signal into a signal affected by body motion and to cancel the body motion signal from the acceleration signal, thereby to produce an acceleration-based cardiac-related signal.

2. The heart monitor claimed in claim 1 further comprising an electronic display operable to display the cardiac-related signal.

3. The heart monitor claimed in claim 1 further comprising an accelerometer package having a broad side wherein said accelerometer has a sensor axis of sensitivity to acceleration approximately perpendicular to the broad side.

4. The heart monitor claimed in claim 1 wherein said digital processor is further operable to count peaks based on said cardiac-related signal to provide a heart rate output.

5. The heart monitor claimed in claim 4 wherein said digital processor is further operable to perform a folded correlation procedure and then threshold process the folded correlation prior to the peak count.

6. The heart monitor claimed in claim 4 wherein said digital processor is further operable to perform an envelope-based noise rejection procedure on the cardiac-related signal prior to the peak count.

7. The heart monitor claimed in claim 1 wherein said digital processor is further operable to perform a folded correlation procedure on the cardiac-related signal.

8. The heart monitor claimed in claim 1 further comprising a wireless link coupling the accelerometer with the analog signal conditioning and sampling section.

9. The heart monitor claimed in claim 1 further comprising a wireless modem fed by said digital processor.

10. The heart monitor claimed in claim 1 further comprising a wireless modem, and wherein said digital processor is further operable to count peaks based on said cardiac-related signal to provide a heart rate output to said modem.

11. A data communication system comprising:

a short range wireless circuit;

a modem; and

a digital processor operable to digitally low-pass filter in response to said short range wireless circuit with a first rolloff frequency less than about one hundred Hertz to produce a first signal, and said digital processor further operable to apply a smoothing filter procedure to produce a slow wander signal, and to cancel the slow wander signal from the first signal to produce a second signal, and to generate data based on counting peaks based on said second signal and feed a third signal representing the data to said modem.

12. The data communication system claimed in claim 11 wherein the third signal represents a bio-medical related signal.

13. The data communication system claimed in claim 11 wherein the smoothing filter procedure includes a polynomial smoothing filter.

14. The data communication system claimed in claim 11 wherein said digital processor is operable to apply a folded correlation process to said second signal and count peaks from the folded correlation process to produce the third signal.

15. The data communication system claimed in claim 11 wherein said modem includes a wireless local area network (WLAN) modem.

16. The data communication system claimed in claim 11 wherein said modem is selected from the group consisting of 1) cellular modem, 2) digital subscriber line (DSL) modem, 3) cable modem.

17. The data communication system claimed in claim 11 wherein said short range wireless circuit is selected from the group consisting of 1) Bluetooth circuit, 2) Zigbee circuit.

18. An electronic process comprising:

sensing an original signal with an accelerometer;

digitally low-pass filtering in response to the original signal and with a rolloff frequency less than about one hundred Hertz to produce a first filtered signal including components among which is a slow wander;

digitally smoothing-filtering in response to the first filtered signal according to a procedure that substantially follows the slow wander in the first filtered signal thereby to produce a slow wander signal; and

canceling the slow wander signal from said first filtered signal.

19. The process claimed in claim 18 further comprising electronically executing the smoothing-filtering with a polynomial smoothing filter procedure including multiply-accumulation of the first filtered signal with coefficients in real time.

20. The process claimed in claim 19 wherein said polynomial smoothing filter includes a filter procedure at a polynomial order at least approximately 20^th order.

21. The process claimed in claim 19 wherein said smoothing-filtering successively encompasses a portion of the first filtered signal of at least approximately 0.4 second duration and a number of points at least approximately half again an order of the polynomial.

22. The process claimed in claim 18 wherein said rolloff frequency is up to approximately 50 Hertz.

23. The process claimed in claim 18 further comprising decimating the first filtered signal prior to the smoothing-filtering.

24. The process claimed in claim 18 wherein the canceling produces a second signal, the process further comprising executing a folded correlation procedure on the second signal strengthening peaks therein.

25. The process claimed in claim 18 further comprising electronically sampling based on the original signal and converting to digital form for the digital low-pass filtering.

26. The process claimed in claim 25 further comprising anti-alias filtering based on the original signal prior to the sampling.

27. The process claimed in claim 26 further comprising coupling the original signal with approximately three Hertz cutoff for coupling mostly above cutoff to the anti-alias filtering.

28. An electronic signal processing system comprising:

a streaming data interface;

a nonvolatile memory holding instructions representing a filtering process and coefficients; and

an electronic processor coupled to said nonvolatile memory to operate in accordance with the instructions, said processor having an input coupled to said streaming data interface for a streaming data signal including noise and operable to digitally electronically execute a smoothing-filter-based procedure on the streaming data signal by a multiply-accumulation with at least some of the coefficients stored in said nonvolatile memory, the coefficients and procedure of a type adapted to reduce the noise and to largely remove slow variations thereby to produce a residue stream, said streaming data interface having an output for a signal based on the residue stream.

29. The electronic signal processing system claimed in claim 28 wherein said electronic processor is operable to electronically execute the smoothing-filter-based procedure with a polynomial transform-based smoothing filter procedure included.

30. The electronic signal processing system claimed in claim 28 further comprising a human-assistance device coupled to an output said electronic processor.

31. The electronic signal processing system claimed in claim 28 further comprising a sampling circuit with an analog to digital converter feeding said streaming data interface.

32. The electronic signal processing system claimed in claim 28 wherein said electronic processor is operable to electronically selectively combine plural streaming data signals in variable proportions to produce a combined signal for the smoothing filter procedure.

33. The electronic signal processing system claimed in claim 28 wherein the coefficients have values substantially related to C=[1 0 0 . . . 0] (A^TA)⁻

1 A^T, where A represents a matrix of a transform.

34. The electronic signal processing system claimed in claim 28 wherein said electronic processor is operable to electronically execute the smoothing-filter-based procedure selectively according to a multiply-accumulation with the streaming data signal of selected sets of coefficients representing different filters.