Method and device for detecting anomalous events for an electronic apparatus, in particular a portable apparatus

• US 7,979,235 B2
• Filed: 01/22/2009
• Issued: 07/12/2011
• Est. Priority Date: 01/22/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Pasolini, Fabio, Ressia, Alberto
• Primary Examiner(s): TEIXEIRA MOFFAT, JONATHAN CHARLES
• Application Number:
  US12/357,620
• Publication Number:
  US 20090187370A1
• Time in Patent Office: 901 Days
• Field of Search: 702/141
• US Class Current: 702/141
• CPC Class Codes: G01P 1/006 used for thermal compensation
• CPC Class Codes: G01P 15/00 Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G11B 19/042 due to external shock or vibration
• CPC Class Codes: G11B 19/043 by detecting a free-fall condition

Abstract

Detection of an anomalous event in an electronic apparatus includes detecting accelerations acting on the electronic apparatus, establishing a normal-mode range of accelerations that corresponds to normal operation of the apparatus, and detecting the anomalous event when a level of acceleration of the electronic apparatus exits the normal-mode range and remains outside the normal mode range for more than a defined duration. The method includes displacing the normal-mode range toward a current level of acceleration of the electronic apparatus while the level of acceleration remains outside the normal-mode range. Additionally, the normal-mode range is increased toward a maximum size while the level of acceleration remains outside the normal-mode range, and is decreased toward a minimum size while the level of acceleration is within the normal-mode range.

Claims

1. A method, comprising:

generating an acceleration signal indicative of an acceleration acting on an electronic apparatus;

detecting an anomalous event of the apparatus as a function of said acceleration signal, including;

monitoring a normal-mode condition of said electronic apparatus;

detecting exits of said electronic apparatus from said normal-mode condition,

determining durations of residence of said electronic apparatus outside said normal-mode condition,

detecting said anomalous event as a function of a sum of two successive ones of said durations of residence outside of said normal-mode condition, provided an intervening duration of residence of said electronic apparatus within said normal-mode condition is less than a selected threshold; and

acting to protect the electronic apparatus upon detection of the anomalous event.

2. The method according to claim 1 wherein said step of monitoring a normal-mode condition comprises:

determining a variation of acceleration associated with said acceleration signal;

executing a comparison between said variation of acceleration and an acceleration threshold; and

determining residence in, or exit from, said normal-mode condition according to the result of said comparison.

3. The method according to claim 2 wherein said step of monitoring a normal-mode condition further comprises setting the value of said acceleration threshold as a function of given characteristics of said electronic apparatus.

4. The method according to claim 2 wherein said step of determining said variation of acceleration comprises determining a variation between a current value and a previous value of said acceleration signal.

5. The method according to claim 2 wherein said step of determining said variation of acceleration comprises:

filtering said acceleration signal with a filter having a given cut-off frequency so as to obtain a filtered acceleration signal; and

determining said variation of acceleration as a difference between a signal correlated to said acceleration signal and said filtered acceleration signal.

6. The method according to claim 5 wherein said step of determining said variation of acceleration further comprises filtering said acceleration signal with a further filter having a cut-off frequency higher than said given cut-off frequency so as to obtain said signal correlated to said acceleration signal.

7. The method according to claim 2 wherein said step of detecting said anomalous event further comprises:

varying dynamically the value of said acceleration threshold according to the result of said comparison.

8. The method according to claim 7 wherein said step of varying dynamically the value of said acceleration threshold comprises increasing the value of said acceleration threshold from a lower value to a higher value upon exit from said normal-mode condition, and decreasing the value of said acceleration threshold from said higher value to said lower value, upon entry into said normal-mode condition.

9. The method of claim 1 wherein the step of determining a first duration of residence comprises determining that the first duration of residence is greater than a selected duration threshold.

10. A device for detecting an anomalous event in an electronic apparatus, comprising:

an accelerometer sensor, configured to produce at least one acceleration signal indicative of an acceleration acting on said electronic apparatus; and

a processing circuit, including;

a monitoring stage, configured to monitor a normal-mode condition of said electronic apparatus; and

a detection stage, coupled to said monitoring stage, and configured to detect an exit of said electronic apparatus from said normal-mode condition, to determine a duration of residence of said apparatus outside said normal-mode condition, and to detect said anomalous event as a function of said exit from and duration of residence of said electronic apparatus outside said normal-mode condition and configured to detect said anomalous event as a function of a sum of durations of two periods of residence outside said normal-mode condition provided an intervening return to said normal-mode condition is for a period of less than a selected duration.

11. The device according to claim 10 wherein said monitoring stage comprises determination means for determining a variation of acceleration associated with said acceleration signal, and comparison means for comparing said variation of acceleration with an acceleration threshold;

and wherein said detection stage is configured to determine residence in, or exit from, said normal-mode condition according to the result of said comparison.

12. The device according to claim 11 wherein said monitoring stage further comprises setting means, operable to set the value of said acceleration threshold according to given characteristics of said electronic apparatus.

13. The device according to claim 11 wherein said determination means are configured so as to determine a variation between a substantially current value and a previous value of said acceleration signal.

14. The device according to claim 11 wherein said determination means comprise:

filtering means configured to filter said acceleration signal with a given cut-off frequency so as to generate a filtered acceleration signal; and

subtractor means, configured to determine said variation of acceleration as a difference between a signal correlated to said acceleration signal and said filtered acceleration signal.

15. The device according to claim 14 wherein said determination means further comprise further filtering means configured to generate said signal correlated to said acceleration signal;

said filtering means having a cut-off frequency lower than said further filtering means.

16. The device according to claim 15 wherein said filtering means include an IIR filter and said further filtering means include a FIR filter.

17. The device according to claim 11 wherein said detection stage further comprises a counter stage, configured to determine the duration of residence of said apparatus outside said normal-mode condition.

18. The device according to claim 11 wherein said detection stage further comprises a threshold-variation stage, configured to vary dynamically the value of said acceleration threshold according to the result of said comparison.

19. The device according to claim 18 wherein said threshold-variation stage is configured to increase the value of said acceleration threshold from a lower value toward a higher value upon exit from said normal-mode condition, and decrease the value of said acceleration threshold toward said lower value upon entry into said normal-mode condition.

20. The device according to claim 11 for an electronic apparatus, further comprising protection means configured to perform operations of protection of said device upon detection of said anomalous event.

21. The device of claim 10 wherein the detection stage is configured to determine that the duration of residence of the apparatus outside the normal-mode condition is at least a period equal to a selected duration threshold.

22. An electronic apparatus, comprising:

a microprocessor control circuit;

a detection device including;

an accelerometer sensor, configured to produce at least one acceleration signal indicative of an acceleration acting on said electronic apparatus; and

a processing circuit, separate from the microprocessor control circuit, configured to detect an anomalous event as a function of said acceleration signal, the processing circuit configured to monitor a normal-mode condition of said electronic apparatus and to detect said anomalous event based on duration of residence of said electronic apparatus outside said normal-mode condition, and also to detect said anomalous event based on a sum of the duration of residence outside said normal-mode condition and of a second duration of residence outside said normal-mode condition if an intervening period of residence within said normal-mode condition is less than a threshold duration, the processing circuit further configured to increase, toward a maximum value, a threshold defining the normal mode condition if the electronic apparatus exits the normal mode region.

23. The apparatus according to claim 22, further comprising a hard-disk device and a control circuit connected to said hard-disk device;

said detection device being configured to supply to said control circuit a detection signal upon detection of said anomalous event, and said control circuit being configured to activate a protective action of said hard-disk device upon reception of said detection signal.

24. A method, comprising:

detecting acceleration of an electronic apparatus;

establishing a range of accelerations that defines a normal-mode region of the electronic apparatus based on a first detected level of acceleration;

detecting an acceleration that falls outside the normal-mode region;

determining a first duration of residence of the electronic apparatus outside, the normal-mode region;

signaling detection of an anomalous event if the first duration of residence exceeds a first duration threshold;

determining a duration of residence of the electronic apparatus within the normal-mode region following the first residence of the electronic apparatus outside the normal-mode region;

if the duration of residence of the electronic apparatus within the normal-mode region is less than a second duration threshold, then determining a second duration of residence of the electronic apparatus outside the normal-mode region that follows the residence of the electronic apparatus within the normal-mode region; and

signaling detection of an anomalous event if a sum of the first duration of residence and the second duration of residence exceeds the first duration threshold.

25. The method of claim 24, comprising:

increasing, while the electronic apparatus resides outside the normal-mode region, the range of accelerations that defines the normal-mode region of the electronic apparatus toward a maximum range; and

decreasing, while the electronic apparatus resides within the normal-mode region, the range of accelerations that defines the normal-mode region of the electronic apparatus toward a minimum range.

26. The method of claim 24, comprising:

displacing, while the electronic apparatus resides outside the normal-mode region, the range of accelerations that defines the normal-mode region toward a current value of acceleration of the electronic apparatus.