Fall Detection Methods and Devices

• US 20120259577A1
• Filed: 09/29/2011
• Published: 10/11/2012
• Est. Priority Date: 04/11/2011
• Status: Active Grant

• Current Assignee: Fidelity Investments Corporation (FMR LLC)
• Original Assignee: Transrex AG
• Inventors: Ganyi, Tibor
• Granted Patent: US 9,427,177 B2
• Time in Patent Office: Days
• US Class Current: 702/139
• CPC Class Codes: A61B 2560/0257 using atmospheric pressure
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/1117 Fall detection
• CPC Class Codes: A61B 5/1122 of movement trajectories
• CPC Class Codes: A61B 5/6822 Neck
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses
• CPC Class Codes: G08B 21/043 detecting an emergency event, e.g. a fall
• CPC Class Codes: G08B 21/0446 worn on the body to detect changes of posture, e.g. a fall, inclination, acceleration, gait

Abstract

A fall detection device includes a fall detection circuit to detect a fall by a user and a verification circuit to verify the initial indication of a fall from the fall detection circuit. The device is sized to be worn by the user and includes an orientation sensor to track the orientation of the device relative to one or more axes. The device averages the average inclination values for one or more axes for time periods before, during, and after the fall. A fall is determined to have occurred when differences in the average values of the inclination values exceed threshold values.

Claims

1. A method of using a device to separate correct and incorrect user fall detections, said method comprising:

receiving an initial indication of a potential fall;

measuring, by the device, an inclination of the device worn by the user relative to one or more different axes at a first plurality of time instants before the initial indication of the potential fall and for a second plurality of time instants during the potential fall;

responsive to the initial indication, comparing, by the device, the inclination of the device during the potential fall to the inclination of the device before the potential fall; and

verifying, by the device, that a correct fall detection and a fall has occurred based on said comparison.

2. The method of claim 1, wherein comparing the inclination of the device during the potential fall to the inclination of the device before the potential fall comprises:

calculating an average inclination of the device before the potential fall from the first plurality of measurements;

calculating an average inclination of the device during the potential fall from the second plurality of measurements; and

calculating a difference between the average inclination of the device during the potential fall and the average inclination of the device before the potential fall.

3. The method of claim 2, wherein verifying that a correct fall detection occurred based on said comparing the inclination of the device during the potential fall to the inclination of the device before the potential fall comprises:

determining that the fall detection is correct and a fall has occurred if the difference exceeds a threshold; and

determining that the fall detection is incorrect and a fall has not occurred if the difference is less than a threshold.

4. The method of claim 1 further comprising:

measuring, by the device, an inclination of the device relative to one or more different axes for a third plurality of time instants after the potential fall;

responsive to the initial indication, comparing the inclination of the device after the potential fall to the inclination of the device before the potential fall; and

verifying, by the device, that a correct fall detection and a fall has occurred based on said second comparison.

5. The method of claim 4, wherein comparing the inclination of the device after the potential fall to the inclination of the device before the potential fall comprises:

calculating an average inclination of the device after the potential fall from the third plurality of measurements; and

calculating a difference between the average inclination of the device after the potential fall and the average inclination of the device before the potential fall.

6. The method of claim 5, wherein verifying that a correct fall detection occurred based on said comparing the inclination of the device after the potential fall to the inclination of the device before the potential fall comprises:

determining that the fall detection is correct and a fall has occurred if the difference exceeds a threshold; and

determining that the fall detection is incorrect and a fall has not occurred if the difference is less than a threshold.

7. The method of claim 1, wherein measuring an inclination of the device relative to one or more different axes comprises measuring an inclination of the device relative to three orthogonal axes.

8. The method of claim 7, wherein measuring an inclination of the device comprises measuring the inclination of the device relative to the three orthogonal axes using a single three-axis accelerometer.

9. A method of using a device to separate correct from incorrect user fall detections, said method comprising:

receiving an initial indication of a potential fall;

measuring, by the device, an inclination of the device worn by the user relative to one or more different axes at a first plurality of time instants in a first time period before the initial indication of the potential fall, a second plurality of time instants in a second time period during the potential fall including the initial indication, and a third plurality of time instants in a third time period after the initial indication of the potential fall;

calculating, by the device from said measurements, an average inclination for each of the one or more axes for the first time period, the second time period, and the third time period;

calculating, by the device, a first difference between the average inclination for the second time period and the average inclination for the first time period for at least one of the axes;

calculating, by the device, a second difference between the average inclination for the third time period and the average inclination for the first time period for at least one of the axes; and

verifying, by the device, that a correct fall detection has occurred if the first or second difference exceeds a threshold.

10. The method of claim 9, wherein receiving the initial indication of the potential fall includes receiving a signal from the device worn by the user.

11. The method of claim 10, wherein the device comprises at least one of a pressure sensor, gyroscope, magnetometer, or accelerometer.

12. The method of claim 9, wherein measuring an inclination of the device relative to one or more different axes comprises measuring an inclination of the device relative to three orthogonal axes.

13. The method of claim 12, wherein measuring an inclination of the device comprises measuring the inclination of the device relative to the three orthogonal axes using a single three-axis accelerometer.

14. A fall detection device that is worn by a user comprising:

a fall detection circuit to provide an initial indication of a potential fall;

an orientation sensor to measure an inclination of the user;

a verification circuit for verifying that a correct fall detection has occurred, said verification circuit configured to;

receive an initial indication of the potential fall from the fall detection circuit;

from measurements of the orientation sensor, determine an inclination of the device relative to one or more different axes for a first plurality of time instants before the potential fall and for a second plurality of time instants during the potential fall;

compare, responsive to the initial indication, the inclination of the device during the potential fall to the inclination of the device before the potential fall; and

verify that a correct fall detection occurred based on said comparison.

15. The fall detection device of claim 14, wherein the verification circuit compares the inclination of the device during the potential fall to the inclination of the device before the potential fall by:

calculating an average inclination of the device before the potential fall from the first plurality of measurements;

calculating an average inclination of the device during the potential fall from the second plurality of measurements; and

calculating a difference between the average inclination of the device during the potential fall and the average inclination of the device before the potential fall.

16. The fall detection device of claim 15, wherein the verification circuit verifies that the correct fall detection occurred based on a comparison of the inclination of the device during the potential fall to the inclination of the device before the potential fall by:

determining that the fall detection is correct and a fall has occurred if the difference exceeds a threshold; and

determining that the fall detection is incorrect and a fall has not occurred if the difference is less than a threshold.

17. The fall detection device of claim 14, wherein the verification circuit is further configured to:

measure an inclination of the device relative to one or more different axes for a third plurality of time instants after the potential fall;

compare, responsive to the initial indication, the inclination of the device after the potential fall to the inclination of the device before the potential fall; and

verify that a correct fall detection occurred based on said second comparison.

18. The fall detection device of claim 17, wherein the verification circuit compares the inclination of the device after the potential fall to the inclination of the device before the potential fall by:

calculating an average inclination of the device after the potential fall from the third plurality of measurements; and

calculating a difference between the average inclination of the device after the potential fall and the average inclination of the device before the potential fall.

19. The fall detection device of claim 18, wherein the verification circuit verifies that a correct fall detection occurred based on a comparison of the inclination of the device after the potential fall to the inclination of the device before the potential fall by:

determining that the fall detection is correct and a fall has occurred if the difference exceeds a threshold; and

determining that the fall detection is incorrect and a fall has not occurred if the difference is less than a threshold.

20. The fall detection device of claim 14 wherein the fall detection circuit and orientation sensor are contained in a common housing.