Activity Detection in MEMS Accelerometers
First Claim
1. A method for detecting activity and inactivity in a MEMS accelerometer, the method comprising:
- using circuitry to measure a dynamic component of acceleration;
using circuitry to compare the dynamic component to an activity threshold to detect activity;
using circuitry to detect inactivity once activity is detected, comprising;
measuring a dynamic component of acceleration; and
using circuitry to determine if the dynamic component of acceleration is less than an inactivity threshold and to determine if a predetermined period of time has elapsed to detect inactivity,wherein the accelerometer is implemented as an integrated circuit and wherein a pin of the integrated circuit is configured to present a first value when the last state detected is activity and to present a second value when the last state detected is inactivity, andwherein using circuitry to compare the dynamic component of acceleration to an activity threshold to detect activity determines if the dynamic component of acceleration exceeds the activity threshold at a plurality of intervals and only detects activity if the dynamic component of acceleration exceeds the threshold during each interval.
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Abstract
A method of detecting activity with a MEMS accelerometer stores a value of acceleration, then measures acceleration at a later time, calculates a change in acceleration using the measured acceleration and the stored acceleration, and compares the change in acceleration to an activity threshold to detect activity. A method of detecting inactivity uses a similar technique along with a timer. The method of detecting inactivity with a MEMS accelerometer stores an acceleration value, then measures acceleration at a later time, calculates a change in acceleration using the measured acceleration and the stored acceleration, and compares the change in acceleration to an inactivity threshold. If the change in acceleration is less than the inactivity threshold and, if a predetermined period of time has elapsed, then inactivity is detected.
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Citations
16 Claims
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1. A method for detecting activity and inactivity in a MEMS accelerometer, the method comprising:
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using circuitry to measure a dynamic component of acceleration; using circuitry to compare the dynamic component to an activity threshold to detect activity; using circuitry to detect inactivity once activity is detected, comprising; measuring a dynamic component of acceleration; and using circuitry to determine if the dynamic component of acceleration is less than an inactivity threshold and to determine if a predetermined period of time has elapsed to detect inactivity, wherein the accelerometer is implemented as an integrated circuit and wherein a pin of the integrated circuit is configured to present a first value when the last state detected is activity and to present a second value when the last state detected is inactivity, and wherein using circuitry to compare the dynamic component of acceleration to an activity threshold to detect activity determines if the dynamic component of acceleration exceeds the activity threshold at a plurality of intervals and only detects activity if the dynamic component of acceleration exceeds the threshold during each interval. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A device for detecting activity and inactivity in a MEMS accelerometer, the device comprising:
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circuitry configured to measure a dynamic component of acceleration; circuitry configured to compare the dynamic component to an activity threshold to detect activity; circuitry configured to detect inactivity once activity is detected, comprising, circuitry configured to measure a dynamic component of acceleration; and circuitry configured to determine if the dynamic component of acceleration is less than an inactivity threshold and to determine if a predetermined period of time has elapsed to detect inactivity, wherein the device is implemented as an integrated circuit and wherein a pin of the integrated circuit is configured to present a first value when the last state detected is activity and to present a second value when the last state detected is inactivity, and wherein circuitry configured to compare the dynamic component of acceleration to an activity threshold to detect activity is configured to determine if the dynamic component of acceleration exceeds the threshold at a plurality of intervals and only detect activity if the dynamic component of acceleration exceeds the threshold during each interval. - View Dependent Claims (8)
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9. A device for detecting activity in a MEMS accelerometer, the device comprising:
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circuitry configured to store a first acceleration value as measured by the accelerometer in a memory at a first time; circuitry configured to then measure a second acceleration value with the accelerometer at a predetermined time, the predetermined time later than the first time; circuitry configured to calculate a change in acceleration equal to the difference between the second acceleration value and the stored first acceleration value from the memory; and circuitry configured to compare the change in acceleration to a threshold to detect activity. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification