Detecting falls using a mobile device

1. A method comprising:

obtaining, by a mobile device, a first signal indicating an acceleration measured by an accelerometer over a time period, and a second signal indicating an orientation measured by an orientation sensor over the time period, wherein the accelerometer and the orientation sensor are physically coupled to a user;

determining, by the mobile device, rotation data indication an amount of rotation experienced by the user during the time period;

determining, by the mobile device, that the user has tumbled based on the rotation data; and

responsive to determining that the user has tumbled, generating, by the mobile device, a notification indicating that the user has tumbled.

2. The method of claim 1 , wherein the rotation data comprises a third signal indicating a rotation rate experienced by the user during the time period.

3. The method of claim 2 , wherein the rotation data indicating an indication of one or more rotational axes of the rotation in a reference coordinate system by the user during the time period.

4. The method of claim 3 , wherein the rotation data comprises an indication of an average rotational axis of the rotation by the user during the time period.

5. The method of claim 4 , wherein determining that the user has tumbled comprises:

determining a variation between the one or more rotational axes of the rotation by the user during the time period and the average rotational axis of the rotation by the user during the time period.

6. The method of claim 5 , wherein determining that the user has tumbled comprises:

determining that the variation is less than a first threshold value; and

responsive to determining that the variation is less than the first threshold value, determining a fourth signal corresponding to an angular displacement of the user during the time period based on the third signal.

7. The method of claim 6 , wherein determining the fourth signal comprises integrating the third signal with respect to the time period.

8. The method of claim 6 , wherein determining that the user has tumbled comprises:

determining that the angular displacement of the user during the time period is greater than a second threshold value;

determining that at least one of the one or more rotational axes of the rotation by the user during the time period is greater than a third threshold value; and

responsive to determining that the angular displacement experienced of the user during the time period is greater than the second threshold value and determining that at least one of the one or more rotational axes of the rotation by the user during the time period is greater than the third threshold value, determining that the user has tumbled.

9. The method of claim 1 , wherein generating the notification comprises presenting an indication that the user has tumbled on at least one of a display device or an audio device of the mobile device.

10. The method of claim 1 , wherein generating the notification comprises transmitting data to a communications device remote from the mobile device, the data comprising an indication that the user has tumbled.

11. The method of claim 1 , wherein the method is performed by one or more co-processors of the mobile device, and

wherein the one or more co-processors are configured to receive motion data obtained from one or more sensors, process the motion data, and provide the processed motion data to one or more other processors of the mobile device.

12. A system comprising:

an accelerometer configured to be physically coupled to a user

an orientation sensor configured to be physically coupled the user;

one or more processors; and

one or more non-transitory computer readable media storing instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising:

obtaining a first signal indicating an acceleration measured by the accelerometer over a time period, and a second signal indicating an orientation measured by the orientation sensor over the time period;

determining rotation data indication an amount of rotation experienced by the user during the time period;

determining that the user has tumbled based on the rotation data; and

responsive to determining that the user has tumbled, generating a notification indicating that the user has tumbled.

13. The system of claim 12 , wherein the rotation data comprises a third signal indicating a rotation rate experienced by the user during the time period.

14. The system of claim 13 , wherein the rotation data indicating an indication of one or more rotational axes of the rotation in a reference coordinate system by the user during the time period.

15. The system of claim 14 , wherein the rotation data comprises an indication of an average rotational axis of the rotation by the user during the time period.

16. The system of claim 15 , wherein determining that the user has tumbled comprises:

determining a variation between the one or more rotational axes of the rotation by the user during the time period and the average rotational axis of the rotation by the user during the time period.

17. The system of claim 16 , wherein determining that the user has tumbled comprises:

determining that the variation is less than a first threshold value; and

responsive to determining that the variation is less than the first threshold value, determining a fourth signal corresponding to an angular displacement of the user during the time period based on the third signal.

18. The system of claim 17 , wherein determining the fourth signal comprises integrating the third signal with respect to the time period.

19. The system of claim 17 , wherein determining that the user has tumbled comprises:

determining that the angular displacement of the user during the time period is greater than a second threshold value;

determining that at least one of the one or more rotational axes of the rotation by the user during the time period is greater than a third threshold value; and

responsive to determining that the angular displacement experienced of the user during the time period is greater than the second threshold value and determining that at least one of the one or more rotational axes of the rotation by the user during the time period is greater than the third threshold value, determining that the user has tumbled.

20. The system of claim 12 , further comprising least one of a display device or an audio device, and wherein generating the notification comprises presenting an indication that the user has tumbled on at least one of the display device or the audio device.

21. The system of claim 12 , wherein generating the notification comprises transmitting data to a communications device remote from the system, the data comprising an indication that the user has tumbled.

22. The system of claim 12 , wherein the one or more processors comprise one or more co-processors, and wherein the one or more co-processors are configured to receive motion data obtained from one or more sensors, process the motion data, and provide the processed motion data to another one of the one or more processors.

23. The system of claim 12 , wherein the system is a mobile device.

24. One or more non-transitory computer readable media storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:

obtaining a first signal indicating an acceleration measured by an accelerometer over a time period, and a second signal indicating an orientation measured by an orientation sensor over the time period, wherein the accelerometer and the orientation sensor are physically coupled to a user;

determining rotation data indication an amount of rotation experienced by the user during the time period;

determining that the user has tumbled based on the rotation data; and

responsive to determining that the user has tumbled, generating a notification indicating that the user has tumbled.