# US 8,464,571 B1 · Systems and methods for determining resonant frequency and quality factor of overdamped systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,464,571 B1 - Document ID: US8464571B1 - Status: Granted - Kind: B1 - Application number: 12/728,867 - Filed: 2010-03-22 - Granted: 2013-06-18 - Earliest claimed: 2009-03-20 - Assignees: Analog Devices, Inc. - Applicants: Andrew Sparks; Michael Judy - Inventors: Andrew Sparks; Michael Judy - Web page: https://patentgrep.com/patent/US8464571B1 ## CPC - G01P 21/00: Testing or calibrating of apparatus or devices covered by the preceding groups - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) ## Abstract A calibration system for a MEMS system having at least one overdamped motion axis includes a measurement module for determining a location of a pole of a MEMS device in the overdamped motion axis, a closed-loop feedback system configured to change a first location of the pole to a second location of the pole, and a computation module for calculating a resonant frequency and/or a quality factor using the first and the second location of the pole as determined by the measurement module. The calibration system further includes a calibration module for calibrating the MEMS system based on the calculated resonant frequency and/or the calculated quality factor. ## Claims ### Claim 1 A calibration system for a MEMS system that is overdamped along at least one motion axis, the system comprising: a measurement module for determining a location of a pole of a MEMS device along the at least one motion axis; a closed-loop feedback system configured to change a first location of the pole to a second location of the pole; a computation module for calculating a resonant frequency, a quality factor, or both using the first and the second location of the pole as determined by the measurement module; and a calibration module for calibrating the MEMS system based on the calculated resonant frequency, the calculated quality factor, or both. ### Claim 2 (depends on 1) The calibration system of claim 1, wherein the closed-loop feedback system is configured to regulate position, velocity, or both. ### Claim 3 (depends on 1) The calibration system of claim 1, wherein the closed-loop feedback system is a positive feedback system, a negative feedback system, or both. ### Claim 4 (depends on 1) The calibration system of claim 1, wherein the MEMS device is a MEMS sensor. ### Claim 5 (depends on 1) The calibration system of claim 1, wherein the MEMS sensor is an accelerometer. ### Claim 6 A method of calibrating a MEMS system, the method comprising: providing a MEMS device that is overdamped along at least one motion axis; determining a first location of a pole of the MEMS device along the at least one motion axis; changing the first location to a second location; determining the second location of the pole; calculating a resonant frequency, a quality factor, or both using the first and the second location of the pole; and calibrating the MEMS system based on the calculated resonant frequency, the calculated quality factor, or both. ### Claim 7 (depends on 6) The method of claim 6, wherein the first location of the pole is determined by performing a localized frequency sweep. ### Claim 8 (depends on 6) The method of claim 6, wherein changing the first location is accomplished by a closed-loop feedback system. ### Claim 9 (depends on 8) The method of claim 8, wherein the closed-loop feedback system includes regulating position, velocity, or both. ### Claim 10 (depends on 8) The method of claim 8, wherein the closed-loop feedback system is a positive feedback system, a negative feedback system, or both. ### Claim 11 (depends on 6) The method of claim 6, wherein the MEMS device is a MEMS accelerometer. ### Claim 12 (depends on 6) The method of claim 6, further comprising changing an initial location of the pole to the first location before determining the first location of the pole. ### Claim 13 (depends on 12) The method of claim 12, wherein changing the initial location is accomplished by a closed-loop feedback system. ### Claim 14 (depends on 13) The method of claim 13, wherein changing the first location is accomplished by the closed-loop feedback system. ### Claim 15 (depends on 6) The method of claim 6, wherein the MEMS device has two poles, one having a higher frequency and one having a lower frequency, wherein the first location and the second location are determined for the lower frequency pole. ### Claim 16 A method of detecting a parameter with a MEMS system, the method comprising: providing a MEMS device that is overdamped along at least one motion axis; determining a first location of a pole of the MEMS device along the at least one motion axis; measuring a change in the first location to a second location of the pole; calculating a resonant frequency, a quality factor, or both using the first and the second location of the pole; and determining the parameter based on the calculated resonant frequency, the calculated quality factor, or both. ### Claim 17 (depends on 16) The method of claim 16, further comprising providing a closed-loop feedback system in the MEMS system to change the first location to the second location. ### Claim 18 (depends on 17) The method of claim 17, wherein the closed-loop feedback system is a positive feedback system, a negative feedback system, or both. ### Claim 19 (depends on 16) The method of claim 16, wherein the MEMS device is a MEMS sensor. ### Claim 20 (depends on 16) The method of claim 16, further comprising changing an initial location of the pole to the first location before determining the first location of the pole.