Ultra Low Power Actigraphy Based On Dynamic Threshold

• US 20140215246A1
• Filed: 01/31/2013
• Published: 07/31/2014
• Est. Priority Date: 01/31/2013
• Status: Active Grant

• Current Assignee: Salutron, Inc.
• Original Assignee: Salutron, Inc.
• Inventors: Lee, Yong Jin, Hui, Eddy, Chen, Kaiping
• Granted Patent: US 9,146,605 B2
• Time in Patent Office: Days
• US Class Current: 713/323
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: G04C 10/00 Arrangements of electric power supplies in time pieces circuits G04G19/00; mounting, assembling of components of electromechanical watches G04C3/008, of electronic watches G04G17/00
• CPC Class Codes: G04G 19/12 Arrangements for reducing power consumption during storage
• CPC Class Codes: G04G 21/025 for measuring physiological data
• CPC Class Codes: G06F 1/163 Wearable computers, e.g. on a belt
• CPC Class Codes: G06F 1/1694 the I/O peripheral being a single or a set of motion sensors for pointer control or gesture input obtained by sensing movements of the portable computer
• CPC Class Codes: G06F 1/3206 Monitoring of events, devices or parameters that trigger a change in power modality
• CPC Class Codes: G06F 1/3231 Monitoring the presence, absence or movement of users
• CPC Class Codes: G06F 3/03 Arrangements for converting the position or the displacement of a member into a coded form
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A processor for an activity monitor for a user has a reduced power mode in which it does not process data samples from an accelerometer. A wake up circuit or logic evaluates an output from the accelerometer and determines whether the output exceeds a threshold, indicating a threshold amount of activity of the user. If the threshold is exceeded, the wake up circuit or logic causes the processor to enter an active mode. The processor evaluates samples of the accelerometer in an evaluation period and decides whether to continue in the active mode or return to the reduced power mode. If the user is deemed to be sufficiently active, the processor continues in the active mode. In another aspect, the threshold can be set based on an activity level of the user before the reduced power mode or sensor data such as ambient light level or skin temperature.

Claims

1. An activity monitor, comprising:

an accelerometer, the accelerometer is adapted to be worn by a user;

a circuit, the circuit is in communication with the accelerometer and determines whether an output from the accelerometer exceeds a threshold; and

a processor, the processor is in communication with the accelerometer and the circuit, the processor is adapted to process samples from the accelerometer in an active mode of the processor but not in a reduced power mode of the processor, the circuit causes the processor to enter the active mode from the reduced power mode when the output exceeds the threshold, the processor, upon entering the active mode, evaluates samples from the accelerometer in an evaluation period, and based on the evaluation, determines an activity level of the user, and based on the activity level, determines whether to remain in the active mode or to transition back to the reduced power mode.

2. The activity monitor of claim 1, wherein:

based on the activity level, the processor determines whether to remain in the active mode for a minimum time period.

3. The activity monitor of claim 2, wherein:

the minimum time period is based on the activity level.

4. The activity monitor of claim 1, wherein:

the evaluation period is predetermined.

5. The activity monitor of claim 1, further comprising:

an ambient light sensor, the processor determines whether to remain in the active mode based on an ambient light level indicated by the light sensor.

6. The activity monitor of claim 1, further comprising:

a skin temperature sensor, the processor determines whether to remain in the active mode based on a skin temperature of the user indicated by the skin temperature sensor.

7. The activity monitor of claim 1, wherein:

the output comprises an analog signal from the accelerometer.

8. The activity monitor of claim 1, wherein:

the activity level is determined based on at least one of amplitudes or frequencies of the samples.

9. The activity monitor of claim 1, wherein:

the accelerometer comprises a multiple axis accelerometer, and the output is from one or more axes of the multiple axis accelerometer.

10. The activity monitor of claim 1, wherein:

the circuit, to cause the processor to enter the active mode from the reduced power mode, sends an interrupt request to the processor.

11. A method for determining activity of a user, comprising:

determining if an output from an accelerometer adapted to be worn by a user exceeds a threshold;

if the output exceeds the threshold, evaluating samples from the accelerometer in an evaluation period to analyze an activity level of the user, the samples from the accelerometer are not evaluated to analyze the activity level of the user during the determining; and

based on the activity level of the user, determining whether to continue to evaluate samples from the accelerometer.

12. The method of claim 11, further comprising:

setting the threshold based on a characteristic of the user.

13. The method of claim 11, further comprising:

setting the threshold based on previous activity of the user.

14. The method of claim 11, further comprising:

determining whether to continue to evaluate samples from the accelerometer based on a skin temperature of the user.

15. The method of claim 11, further comprising:

determining whether to continue to evaluate samples from the accelerometer based on an ambient light level.

16. The method of claim 11, further comprising:

determining whether to continue to evaluate samples from the accelerometer based on a time of day.

17. A computer-readable storage apparatus having computer-readable software embodied thereon for programming a processor to perform a method, the method comprising:

obtaining an output from an accelerometer adapted to be worn by a user;

determining if the output exceeds a threshold; and

if the output exceeds the threshold, processing samples of the accelerometer using an active mode of a processor;

receiving data from a sensor adapted to be worn by the user; and

based on the processing of the samples and the data, determining whether to continue the active mode of the processor.

18. The computer-readable storage apparatus of claim 17, wherein:

the sensor comprises an ambient light sensor.

19. The computer-readable storage apparatus of claim 17, wherein:

the sensor comprises a skin temperature sensor.

20. The computer-readable storage apparatus of claim 17, wherein the method performed further comprises:

determining whether to continue the active mode of the processor based on a time of day.

21. An activity monitor, comprising:

an accelerometer, the accelerometer is adapted to be worn by a user; and

a processor, the processor comprises activity analysis logic and wake up logic, the processor is in communication with the accelerometer and the wake up logic determines whether an output from the accelerometer exceeds a threshold, the activity analysis logic is adapted to process samples from the accelerometer in an active mode of the processor but not in a reduced power mode of the processor, the wake up logic causes the processor to enter the active mode from the reduced power mode based on whether the output exceeds the threshold, the processor, upon entering the active mode, uses the activity analysis logic to evaluate samples from the accelerometer in an evaluation period, and based on the evaluation, determine an activity level of the user, and based on the activity level, determine whether to remain in the active mode or to transition back to the reduced power mode.

22. The activity monitor of claim 21, further comprising:

a sensor, the processor uses an input from the sensor to decide whether to remain in the active mode or to transition back to the reduced power mode.

23. The activity monitor of claim 22, wherein:

the sensor comprises a skin temperature sensor.

24. The activity monitor of claim 22, wherein:

the sensor comprises an ambient light sensor.