System and method for fall detection
A system and method is provided for electronic device fall detection. The system and method provides the ability to reliably detect falls even in the presence of other motion in the electronic device. The fall detection system includes a plurality of accelerometers and a processor. The plurality of accelerometers provides acceleration measurements to the processor, with these measurements describing the current acceleration of the electronic device in all directions. The processor receives the acceleration measurements and compares the acceleration measurements to a value range to determine if the device is currently falling. Furthermore, the system and method can reliably detect a non-linear fall, such as when the fall is accompanied with device rotation or initiated by additional external force. To detect a non-linear fall, the processor compares combinations of acceleration measurements to a value range and further determines the smoothness of the acceleration measurement combinations.
1. A system for determining if an electronic device is falling, the system comprising:
a plurality of accelerometers, the plurality of accelerometers adapted to measure electronic device acceleration in a plurality of directions and produce a plurality of acceleration measurements; and
a processor, the processor adapted to receive the plurality of acceleration measurements from the plurality of accelerometers and compare the plurality of acceleration measurements to a value range, and wherein the processor is adapted to determine a fall is occurring if the plurality of acceleration measurements are within the value range, and wherein the processor is further adapted to determine if a non-linear fall is occurring by calculating a combination of the plurality of acceleration measurements and determining a rate of change of the combination of the plurality of acceleration measurements.
2. The system of claim 1 wherein the processor further determines a fall is occurring if the plurality of acceleration measurements are within the value range for a predetermined number of consecutive acceleration measurements.
3. The system of claim 2 wherein the predetermined number of consecutive acceleration measurements comprises 10 consecutive acceleration measurements.
4. The system of claim 1 wherein the processor determines a rate of change of the combination of the plurality of acceleration measurements determining if a selected number of consecutive combinations of the plurality of acceleration measurements each has a change less than a threshold delta value.
5. The system of claim 1 wherein the plurality of accelerometers comprise a first accelerometer providing a first acceleration measurement x, a second accelerometer providing a second acceleration measurement y, and a third accelerometer providing a third acceleration measurement z, and wherein the combination of the plurality of acceleration measurements comprises x 2 +y 2 +z 2 .
6. The system of claim 1 wherein the plurality of accelerometers comprise micro machined accelerometers.
7. The system of claim 1 wherein the plurality of accelerometers comprise a first accelerometer measuring acceleration in a X direction, a second accelerometer measuring acceleration in a Y direction, and a third accelerometer measuring acceleration in a Z direction, where X, Y and Z are perpendicular to each other.
8. The system of claim 1 wherein the processor further determines if a detected fall was accompanied by external force by determining if the combination of the acceleration measurements exceeded a threshold value in a time period prior to the detected fall.
9. A system for determining if an electronic device is falling, the system comprising:
a first accelerometer providing a first acceleration measurements x;
a second accelerometer providing a second acceleration measurements y;
a third accelerometer providing a third acceleration measurements z;
a processor, the processor receiving the first acceleration measurements x, the second acceleration measurements y, and the third acceleration measurements z; the processor comparing the first acceleration measurements x, the second acceleration measurements y, and the third acceleration measurements z to a value range, and wherein the processor determines a fall is occurring if the first acceleration measurements x, the second acceleration measurements y, and the third acceleration measurements z are each within the value range for a first selected number of measurement samples, and wherein the processor further determines if a fall with rotation is occurring if x 2 +y 2 +z 2 is within a second value range and has a rate of change determined as an amount of change less than a threshold delta value for a second selected number of measurement samples.
10. The system of claim 9 wherein the process further determines if a detected fall was accompanied by external force by determining if the combination of x 2 +y 2 +z 2 values exceeded a threshold value in a time period prior to the detected fall.
11. A method for determining if an electronic device is falling, the method comprising the steps of:
measuring electronic device acceleration in a plurality of directions and producing a plurality of acceleration measurements;
comparing the plurality of acceleration measurements to a value range to determine if the plurality of acceleration measurements are within the value range;
determining if a fall with rotation is occurring by calculating a combination of the plurality of acceleration measurements and determining a rate of change of the combination of the plurality of acceleration measurements; and
notifying the electronic device responsive to a determined fall with rotation.
12. The method of claim 11 wherein the step of comparing the plurality of acceleration measurements to a value range comprises comparing a predetermined number of consecutive acceleration measurements.
13. The method of claim 12 wherein the predetermined number of consecutive acceleration measurements comprises 10 consecutive acceleration measurements.
14. The method of claim 11 wherein the step of determining if a fall with rotation is occurring by calculating a combination of the plurality of acceleration measurements and determining a rate of change of the combination of the plurality of acceleration measurements comprises determining if a selected number of consecutive combinations of the plurality of acceleration measurements each has a change less than a threshold delta value.
15. The method of claim 11 wherein the plurality acceleration measurement comprises a first acceleration measurement x, a second acceleration measurement y, and a third acceleration measurement z, and wherein the combination of the plurality of acceleration measurements comprises x 2 +y 2 +z 2 .
16. The method of claim 11 wherein the plurality acceleration measurements are received from a plurality of accelerometers comprise micro machined accelerometers.
17. The method of claim 11 wherein the plurality acceleration measurements are received from the plurality of accelerometers that comprise a first accelerometer measuring acceleration in a X direction, a second accelerometer measuring acceleration in a Y direction, and a third accelerometer measuring acceleration in a Z direction, where X, Y and Z are perpendicular to each other.
18. The method of claim 11 further comprising the step of determining if a detected fall was accompanied by external force by determining if the combination of the acceleration measurements exceeded a threshold value in a time period prior to the detected fall.
19. A method for determining if an electronic device is falling, the method comprising the steps of:
measuring first acceleration measurements x;
measuring second acceleration measurements y;
measuring third acceleration measurements z;
comparing the first acceleration measurements x, the second acceleration measurements y, and the third acceleration measurements z to a value range, wherein a fall is determined to be occurring if the first acceleration measurements x, the second acceleration measurements y, and the third acceleration measurements z are each within the value range for a first selected number of measurements;
combining the first acceleration measurements x, the second acceleration measurements y, and the third acceleration measurements z into a combination of x 2 +y 2 +z 2 values;
comparing the combination of x 2 +y 2 +z 2 values to a second value range, and determining if the combination of x 2 +y 2 +z 2 values has a rate of change determined as an amount of change less than a threshold delta value for a second selected number of measurements; and
notifying the electronic device responsive to the combination of x 2 +y 2 +z 2 values having a rate of change determined as an amount of change less than a threshold delta value for a second selected number of measurements.
20. The method of claim 19 further comprising the step of determining if a detected fall was accompanied by external force by determining if the combination of x 2 +y 2 +z 2 values exceeded a threshold value in a time period prior to the detected fall.