# US 6,191,576 B1 · Method of operating or constructing a geartooth sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,191,576 B1 - Document ID: US6191576B1 - Status: Granted - Kind: B1 - Application number: 09/107,798 - Filed: 1998-06-30 - Granted: 2001-02-20 - Earliest claimed: 1998-06-30 - Assignees: Honeywell Inc. - Inventors: Lamar F. Ricks; Wayne A. Lamb; Peter G. Hancock - Web page: https://patentgrep.com/patent/US6191576B1 ## CPC - G01D 5/24476: {Signal processing (G01D5/2448 - G01D5/24495 take precedence)} - G01D 3/02: with provision for altering or correcting the law of variation - G01D 5/2448: {Correction of gain, threshold, offset or phase control} - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR ## Abstract A geartooth sensor utilizes an algorithm for establishing an adaptive threshold for the switch point of the sensor to minimize drift in the point at which the sensor output changes in relation to the target features it is tracking. The algorithm utilizes measured waveform peak and average outputs and applies a separate empirically derived constant to each value to quickly obtain the major portion of the adaptive threshold value from the product of the first constant and the peak output, and to refine the threshold value further with the product of the second constant and the average output. ## Claims ### Claim 1 A method of operating a geartooth sensor comprising the steps of: (a) obtaining at least one amplified sensor transducer waveform; (b) periodically measuring the peak output (Bpeak) from the sensor transducer waveform and multiplying the peak output by a first constant (M1) resulting in a first product; (c) obtaining an average output of the sensor transducer waveform (Bavg) and multiplying the average output by a second constant (M2) resulting in a second product; (d) adding the first and second products to obtain an adaptive threshold; (e) comparing the adaptive threshold to the sensor transducer waveform to result in an output; and (f) utilizing the output as a switch point to set the operational characteristics of the geartooth sensor. ### Claim 2 (depends on 1) A method of operating a geartooth sensor according to claim 1 further comprising the step of: obtaining the average output by a running calculation of output values. ### Claim 3 (depends on 1) A method of operating a geartooth sensor according to claim 1 further comprising the step of: obtaining the average output by deriving it with a time based integrator. ### Claim 4 (depends on 1) A method of operating a geartooth sensor according to claim 1 further comprising the step of: utilizing the first constant to achieve the least drift from the true point over a range of airgap tolerances. ### Claim 5 (depends on 1) A method of operating a geartooth sensor according to claim 1 further comprising the step of: determining the second constant for multiplication with the average output value which achieves least drift from a true point over a range of airgap tolerances when added to M1 times Bpeak. ### Claim 6 (depends on 1) A method of operating a geartooth sensor according to claim 1 wherein both constants are less than 1.0. ### Claim 7 (depends on 1) A method of operating a geartooth sensor according to claim 1 wherein M1 is greater than M2. ### Claim 8 (depends on 1) A method of operating a geartooth sensor according to claim 1 further comprising the step of: determining Bpeak and Bavg by a digital processor. ### Claim 9 (depends on 1) A method of operating a geartooth sensor according to claim 1 further comprising the step of: determining Bpeak and Bavg by means of analog circuitry. ### Claim 10 A method for constructing a sensing system for a rotating target comprising the steps of: (a) graphically plotting a plurality of output waveforms from a magnetic sensor transducer over a range of airgaps within an expected operating range of airgaps between the target and the sensing system; (b) deriving a constant M1; (c) deriving a constant, M2; and; (d) acquiring Bpeak and Bavg during operation of the sensor, Bpeak corresponding to the peak Gaussian output waveform and Bavg corresponding to the average gaussian output waveform and multiplying Bpeak and Bavg times M1 and M2, respectively, resulting in a first product and a second product, and adding the first and second products thereof resulting in an adaptive threshold switch point which represents an amount of least drift of the sensor switch point from at least one reference point on the target to set the operational characteristics of the sensor. ### Claim 11 A method of operating a geartooth sensor comprising the steps of: (a) periodically obtaining a peak output (Bpeak) of a sensor transducer and applying a first constant (M1) to the peak output to derive a first value (Bmax); (b) obtaining an average output of the sensor transducer (Bavg) and applying a second constant (M2) to the average to obtain a second value (Bmin); (c) combining the first and second values, Bmax and Bmin, to obtain an adaptive threshold; and (d) applying the adaptive threshold as a switch point to set the operational characteristics of the sensor transducer. ### Claim 12 A geartooth sensor comprising: (a) means for periodically obtaining the peak output (Bpeak) of the sensor transducer and applying a first constant (M1) to Bpeak to obtain a first value (Bmax); (b) means for obtaining the average output of the sensor transducer (Bavg) and applying a second constant (M2) to Bavg to obtain a second value (Bmin); (c) means for combining Bmax and Bmin to obtain an adaptive threshold; and (d) means for applying the adaptive threshold as a switch point to set the operational characteristics of the sensor transducer. ### Claim 13 (depends on 12) The geartooth sensor according to claim 12 wherein both constants are less than 1.0. ### Claim 14 (depends on 12) The geartooth sensor according to claim 12 wherein M1 is greater than M2. ### Claim 15 (depends on 12) A method of operating a geartooth sensor according to claim 12 further comprising the step of: digital processing means for obtaining the values M1×Bpeak and M2×Bavg. ### Claim 16 (depends on 12) A method of operating a geartooth sensor according to claim 12 further comprising: analog processing means for obtaining the values M1×Bpeak and M2×Bavg.