Inertial sensor sensing of vibration frequency
AssigneeInvenSense, Inc.
InventorAurelio Pellegrini
Life of this patent
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Abstract
A modified version of a MEMS self-test procedure is presented that can be used to detect the amplitude and frequency of an external vibration from an ambient environment. The method implements processing circuitry that correlates an output sense signal, s(t), with a plurality of periodic signal portions and a plurality of shifted periodic signal portions to generate a plurality of correlation values. A frequency associated with the external vibration is determined based on the plurality of correlation values.
Claims21
A method for identifying a frequency of an external vibration by a microelectromechanical system (MEMS) inertial sensor, comprising:
- generating, by processing circuitry of the MEMS inertial sensor, a frequency scan signal pattern comprising a plurality of periodic signal portions each having a test frequency;
- sensing, by one or more sense electrodes of the inertial sensor, a movement of a proof mass of the inertial sensor over a period of time;
- generating, by the processing circuitry of the inertial sensor, a sense signal based on the sensed movement of the proof mass over the period of time;
- correlating, by the processing circuitry, the sense signal with the frequency scan signal pattern;
- generating, by the processing circuitry, a plurality of correlation values based on the correlating, wherein each of the plurality of correlation values is based on a correlation of the sense signal with one of the plurality of periodic signal portions;
- and
- identifying, by the processing circuitry, a frequency associated with the sense signal based on one or more of the generated plurality of correlation values.
A microelectromechanical system (MEMS) inertial sensor, comprising:
- a frequency scan generator that generates a frequency scan signal pattern, wherein the frequency scan signal pattern comprises a plurality of periodic signal portions each having a test frequency;
- a proof mass that responds to an inertial force;
- one or more sense electrodes that sense a movement of the proof mass;
- sense circuitry coupled to the proof mass, wherein the sense circuitry is configured to generate a sense signal based on the sensed movement of the proof mass detected by the one or more sense electrodes;
- and
- processing circuitry coupled to the sense circuitry;
- wherein the processing circuitry is configured to receive the sense signal generated by the sense circuitry, correlate the sense signal with the plurality of periodic signal portions to determine a plurality of correlation values, and identify a frequency associated with the sense signal based on one or more of the generated plurality of correlation values.
A method for monitoring a suspended spring-mass system and identifying a frequency of an external vibration by a microelectromechanical system (MEMS) inertial sensor, comprising:
- generating, by processing circuitry of the MEMS inertial sensor, a frequency scan signal pattern comprising a plurality of periodic signal portions each having a test frequency;
- providing the frequency scan signal pattern to a self-test drive electrode of the MEMS inertial sensor;
- driving, by the self-test drive electrode, a proof mass of the suspended spring-mass system based on the frequency scan signal pattern;
- sensing, by one or more sense electrodes of the inertial sensor, a movement of a proof mass of the inertial sensor over a period of time during which the frequency scan pattern drives the proof mass;
- generating, by the processing circuitry of the inertial sensor, a sense signal based on the sensed movement of the proof mass over the period of time;
- correlating, by the processing circuitry, the sense signal with the frequency scan signal pattern;
- identifying, by the processing circuitry, a frequency associated with the external vibration based on the correlating;
- and
- identifying, by the processing circuitry, an error associated with the suspended spring-mass system based on the correlating.
Dependencies are inferred from the claim text.