FALLING STATE DETERMINATION FOR DATA STORAGE DEVICE
Determination of when an electronic device such as a data storage device (DSD) is falling. An input is received indicating an acceleration of the electronic device during a time period. A classifier function is calculated using the input and it is determined whether the electronic device is falling based on a calculated value of the classifier function. During a calibration process, acceleration values are recorded representing a plurality of actual falls and a plurality of false falls of the electronic device. Weight values are set for a weighted classifier function using the recorded acceleration values and the weighted classifier function is stored in a memory of the electronic device.
1 . A data storage device (DSD) comprising:
a memory for storing data; and
a controller configured to:
receive an input indicating an acceleration of the DSD during a time period;
calculate a classifier function using the input; and
determine whether the DSD is falling based on a calculated value of the classifier function.
2 . The DSD of claim 1 , wherein the classifier function includes a weighted summation of values derived from the input.
3 . The DSD of claim 2 , wherein the weighting of the classifier function is set as part of a manufacturing process of the DSD.
4 . The DSD of claim 2 , wherein the controller is further configured to adjust the weighting of the classifier function during operation of the DSD.
5 . The DSD of claim 2 , wherein the classifier function is weighted so as to improve an accuracy of actual fall determination over an accuracy of false fall determination.
6 . The DSD of claim 2 , wherein the weighting of the classifier function is determined by minimizing a cost function for inputs representing actual falls and false falls of the DSD.
7 . The DSD of claim 6 , wherein the cost function includes a logistic function.
8 . The DSD of claim 1 , wherein the input includes a series of acceleration values for an acceleration of the DSD detected during the time period.
9 . The DSD of claim 8 , wherein the controller is further configured to calculate the classifier function using absolute values of the acceleration values in the series of acceleration values.
10 . The DSD of claim 8 , wherein the controller is further configured to calculate the classifier function using squares of the acceleration values in the series of acceleration values.
11 . The DSD of claim 1 , wherein the controller is further configured to:
receive an initial input indicating an acceleration of the DSD during an initial time period before the time period; and
determine whether the initial input has reached an initial acceleration threshold before calculating the classifier function.
12 . The DSD of claim 11 , wherein the initial acceleration threshold is based on a proportion of a gravitational acceleration constant.
13 . The DSD of claim 11 , wherein the initial input includes an initial series of acceleration values for an acceleration of the DSD detected during the initial time period, and wherein the controller is further configured to determine that the initial input has reached the initial acceleration threshold when each of the acceleration values in the initial series of acceleration values is less than or equal to the initial acceleration threshold.
14 . The DSD of claim 1 , wherein the time period is based on a safe fall time corresponding to a reduced likelihood of damage to the DSD for falls lasting less than the safe fall time as compared to falls lasting longer than the safe fall time.
15 . The DSD of claim 1 , further comprising a sensor for detecting acceleration of the DSD and providing the input.
16 . A method for determining when an electronic device is falling, the method comprising:
receiving an input indicating an acceleration of the electronic device during a time period;
calculating a classifier function using the input; and
determining whether the electronic device is falling based on a calculated value of the classifier function.
17 . The method of claim 16 , wherein the classifier function includes a weighted summation of values derived from the input.
18 . The method of claim 17 , further comprising adjusting the weighting of the classifier function during operation of the electronic device.
19 . The method of claim 16 , wherein the input includes a series of acceleration values for an acceleration of the electronic device detected during the time period.
20 . The method of claim 19 , further comprising calculating the classifier function using absolute values of the acceleration values in the series of acceleration values.
21 . The method of claim 19 , further comprising calculating the classifier function using squares of the acceleration values in the series of acceleration values.
22 . The method of claim 16 , further comprising:
receiving an initial input indicating an acceleration of the electronic device during an initial time period before the time period; and
determining whether the initial input has reached an initial acceleration threshold before calculating the classifier function.
23 . The method of claim 22 , wherein the initial acceleration threshold is based on a proportion of a gravitational acceleration constant.
24 . The method of claim 22 , wherein the initial input includes an initial series of acceleration values for an acceleration of the electronic device detected during the initial time period.
25 . The method of claim 24 , further comprising determining that the initial input has reached the initial acceleration threshold when each of the acceleration values in the initial series of acceleration values is less than or equal to the initial acceleration threshold.
26 . The method of claim 16 , wherein the time period is based on a safe fall time corresponding to a reduced likelihood of damage to the electronic device for falls lasting less than the safe fall time as compared to falls lasting longer than the safe fall time.
27 . A method for calibrating an electronic device for determining when the electronic device is falling, the method comprising:
recording acceleration values representing a plurality of actual falls and a plurality of false falls of the electronic device;
setting weight values for a weighted classifier function using the recorded acceleration values; and
storing the weighted classifier function in a memory of the electronic device.
28 . The method of claim 27 , further comprising setting the weight values as part of a manufacturing process of the electronic device.
29 . The method of claim 27 , further comprising setting the weight values for the weighted classifier function by minimizing a cost function using the recorded acceleration values.
30 . The method of claim 29 , wherein the cost function includes a logistic function.
31 . The method of claim 29 , wherein the acceleration values for the actual falls are weighted more heavily than the acceleration values for the false falls when minimizing the cost function to improve an accuracy of actual fall determination over an accuracy of false fall determination by the electronic device.