Technology for detecting a fall of a person

• US 9,898,914 B2
• Filed: 01/15/2015
• Issued: 02/20/2018
• Est. Priority Date: 02/17/2014
• Status: Active Grant

• Current Assignee: Henning Marchfeld, Thomas Von Chossy
• Original Assignee: Henning Marchfeld, Thomas Von Chossy
• Inventors: Von Chossy, Thomas, Marchfeld, Henning
• Primary Examiner(s): Kim, Kevin
• Application Number:
  US15/119,360
• Publication Number:
  US 20170061762A1
• Time in Patent Office: 1,132 Days
• Field of Search: 3405737
• 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
• CPC Class Codes: G08B 21/0453 worn on the body to detect health condition by physiological monitoring, e.g. electrocardiogram, temperature, breathing detecting, measuring or recording for diagnostic purposes A61B5/00
• CPC Class Codes: G08B 29/185 Signal analysis techniques for reducing or preventing false alarms or for enhancing the reliability of the system

Abstract

A technology for detecting a fall of a person is provided. A corresponding device (100) comprises an interface (102) which is designed for capturing a time-dependent air pressure signal (600) that is determined by means of at least one air pressure sensor (104, 106) worn on the body of the person. The device (100) also comprises an evaluation unit (108) which is designed for determining a fall height (λ) with respect to an evaluation time (t_e) by means of a window-based signal analysis of the time-dependent air-pressure signal. The window-based signal analysis includes a first time window (702) before the evaluation time and a second time window (704), which does not overlap with the first time window, after the evaluation time. The fall height is determined from a difference between a first filter value that is computed based on the time-dependent air pressure signal in the first time window, and a second filter value that is computed based on the time-dependent air pressure signal in the second time window.

Claims

1. A device (100) for detecting a fall of a person, comprising:

an interface (102) which is designed for capturing a time-dependent air pressure signal (600) that is determined by means of at least one air pressure sensor (104;

104, 106;

104, 106-1, 106-2) worn on the body of the person, and

an evaluation unit (108) which is designed for determining a fall height (λ

) with respect to an evaluation time (t_e) by means of a window-based signal analysis of the time-dependent air-pressure signal, wherein the window-based signal analysis includes a first time window (702) before the evaluation time and a second time window (704), which does not overlap with the first time window, after the evaluation time, and wherein the fall height is determined from a difference between a first filter value that is computed based on the time-dependent air pressure signal in the first time window, and a second filter value that is computed based on the time-dependent air pressure signal in the second time window;

wherein the time-dependent air pressure signal (600) includes a sequence of values associated in each case with a measuring time (706), and the fall height (λ

) is determined with respect to a plurality of evaluation times by incrementally shifting the evaluation time (t_e), the first time window (702), and the second time window (704) by a measuring time of the sequence, to later points in time, and the fall height is determined for each of the evaluation times.

2. The device according to claim 1, wherein the air pressure signal (600) is periodically sampled, and the first time window (702) is temporally separate from the second time window (704) by at least one sampling period.

3. The device according to claim 1, wherein the determination of the fall height disregards the time-dependent air pressure signal (600) between the first time window (702) and the second time window (704).

4. The device according to claim 1, wherein the first filter value and/or the second filter value are/is an average value of the time-dependent air pressure signal.

5. The device according to claim 1, wherein the computation of the first filter value or of the second filter value compensates for a time dependency (800;

900) of the time-dependent air pressure signal.

6. The device according to claim 5, wherein the time dependencies (900) for the first time window (702) and for the second time window (704) are each compensated for independently of one another.

7. The device according to claim 5, wherein in the first time window (702) a first time dependency (902;

F₁(t)) is fitted to the time-dependent air pressure signal, and in the second time window a second time dependency (904;

F₂(t)) is fitted to the time-dependent air pressure signal, the fall height being determined from the difference between the first time dependency (F₁(t_1,max)) at the end time of the first time window, and the second time dependency (F₂(t_2,min)) at the start time of the second time window.

8. The device according to claim 5, wherein for the first time window (702) and for the second time window (704) the same time dependency (800) is compensated for.

9. The device according to claim 5, wherein in the first time window, the time dependency (802;

F(t)), having a first time-independent offset value (C₁) as a fit parameter, is fitted to the time-dependent air pressure signal, and in the second time window, the same time dependency (804;

F(t)), having a second time-independent offset value (C₂) as a fit parameter, is fitted to the time-dependent air pressure signal, the fall height being determined from the difference between the first offset value and the second offset value.

10. The device according to claim 1, wherein for each of the evaluation times, it is checked whether the determined fall height exceeds a first significance criterion (z₁).

11. The device according to claim 1, wherein for each of the evaluation times, it is checked whether the difference between the determined fall height and a height threshold value exceeds a second significance criterion (z₂).

12. The device according to claim 11, wherein an alarm state is set if the second significance criterion (z₂) is exceeded.

13. The device according to claim 12, further comprising a trigger unit (402) which is designed for outputting an alarm signal if, in the alarm state, a fit of the time-dependent air pressure signal in the second time window exceeds a predefined quality criterion (Q).

14. The device according to claim 11, wherein for each evaluation time (t_e), the first time window (702) is incrementally extended toward earlier measuring times (706) until a maximum length of the first time window (702) is reached, until the second significance criterion (z₂) is exceeded, or until the determined fall height falls below the height threshold value by a third significance criterion (z₃).

15. The device according to claim 1, wherein the device further comprises a temperature sensor which is worn on the body and thermally decoupled from the body, and wherein an alarm signal is outputted only if the temperature sensor detects a drop in temperature.

16. A device (100) for detecting a fall of a person, comprising:

an interface (102) which is designed for capturing a time-dependent air pressure signal (600) that is determined by means of at least one air pressure sensor (104;

104, 106;

104, 106-1, 106-2) worn on the body of the person, and

an evaluation unit (108) which is designed for determining a fall height (λ

) with respect to an evaluation time (t_e) by means of a window-based signal analysis of the time-dependent air-pressure signal, wherein the window-based signal analysis includes a first time window (702) before the evaluation time and a second time window (704), which does not overlap with the first time window, after the evaluation time, and wherein the fall height is determined from a difference between a first estimation value that is computed based on the time-dependent air pressure signal in the first time window, and a second estimation value that is computed based on the time-dependent air pressure signal in the second time window;

wherein the computation of the first estimation value or of the second estimation value compensates for a time dependency (800;

900) of the time-dependent air pressure signal; and

wherein at least one of;

in the first time window (702) a first time dependency (902;

F₁(t)) is fitted to the time-dependent air pressure signal, and in the second time window a second time dependency (904;

F₂(t)) is fitted to the time-dependent air pressure signal, the fall height being determined from the difference between the first time dependency (F₁(t_1,max)) at the end time of the first time window, and the second time dependency (F₂(t_2,min)) at the start time of the second time window; and

in the first time window, the time dependency (802;

F(t)), having a first time-independent offset value (C₁) as a fit parameter, is fitted to the time-dependent air pressure signal, and in the second time window, the same time dependency (804;

F(t)), having a second time-independent offset value (C₂) as a fit parameter, is fitted to the time-dependent air pressure signal, the fall height being determined from the difference between the first offset value and the second offset value.

17. A device for detecting a fall of a person, the device comprising:

an interface capturing a time-dependent air pressure signal that is determined using at least one air pressure sensor worn on the body of the person;

and an evaluation unit that determines a fall height (λ

) with respect to an evaluation time (t_e) using a window-based signal analysis of the time-dependent air-pressure signal, wherein the window-based signal analysis includes a first time window (702) before the evaluation time and a second time window (704), which does not overlap with the first time window, after the evaluation time, and wherein the fall height is determined from a difference between a first filter value computed based on the time-dependent air pressure signal in the first time window, and a second filter value computed based on the time-dependent air pressure signal in the second time window;

wherein in the first time window (702) a first time dependency (902;

F₁(t)) is fitted to the time-dependent air pressure signal, and in the second time window a second time dependency (904;

F₂(t)) is fitted to the time-dependent air pressure signal, the fall height being determined from the difference between the first time dependency (F₁(t_1,max)) at the end time of the first time window, and the second time dependency (F₂(t_2,min) at the start time of the second time window.

18. A device for detecting a fall of a person, the device comprising:

an interface capturing a time-dependent air pressure signal that is determined using at least one air pressure sensor worn on the body of the person; and

an evaluation unit that determines a fall height (λ

) with respect to an evaluation time (t_e) using a window-based signal analysis of the time-dependent air-pressure signal, wherein the window-based signal analysis includes a first time window (702) before the evaluation time and a second time window (704), which does not overlap with the first time window, after the evaluation time, and wherein the fall height is determined from a difference between a first filter value computed based on the time-dependent air pressure signal in the first time window, and a second filter value computed based on the time-dependent air pressure signal in the second time window;

wherein the computation of the first filter value or of the second filter value compensates for a time dependency (800;

900) of the time-dependent air pressure signal;

wherein in the first time window, the time dependency (802;

F(t)), having a first time-independent offset value (C₁) as a fit parameter, is fitted to the time-dependent air pressure signal, and in the second time window, the same time dependency (804;

F(t)), having a second time-independent offset value (C₂) as a fit parameter, is fitted to the time-dependent air pressure signal, the fall height being determined from the difference between the first offset value and the second offset value.