Gyroscope noise reduction and drift compensation
First Claim
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1. A system for processing the output of an angular rate sensor, comprising:
- means for reducing noise in the sensor output; and
compensation means for compensating for drift, the compensation means comprisingmeans for initially adjusting the sensor output for a pre-determined rate of drift; and
means for subsequently computing a new rate of drift when the angular rate is less than a pre-defined threshold and adjusting the sensor output in response to the new rate of drift.
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Abstract
A low-cost gyroscope can provide an output approaching the accuracy of more precise instruments by processing the gyroscope output signal. First, a calibration algorithm develops a set of coefficients to predict drift. Second, an adaptive operational algorithm updates the coefficients during periods of inactivity and filters out high and low frequency noise components. An accurate, low-cost, rugged aiming device for a weapon can be realized with a simple, relatively-inexpensive gyroscope by utilizing the foregoing algorithms.
41 Citations
11 Claims
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1. A system for processing the output of an angular rate sensor, comprising:
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means for reducing noise in the sensor output; and compensation means for compensating for drift, the compensation means comprising means for initially adjusting the sensor output for a pre-determined rate of drift; and means for subsequently computing a new rate of drift when the angular rate is less than a pre-defined threshold and adjusting the sensor output in response to the new rate of drift. - View Dependent Claims (2, 3)
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4. A system for processing the output of an angular rate sensor, comprising:
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(a) means for calibrating the sensor output, the means for calibrating including an analog-to-digital converter for converting the sensor output to a digital signal; averaging means for averaging the digital signal; an integrator for integrating the averaged signal; and curve-fitting means, responsive to the integrated signal, for determining an initial set of coefficients of drift through a least-squares curve-fit method; and (b) means for determining the angular movement of the sensor, the means for determining the angular movement including an analog-to-digital converter for converting the sensor output to a digital signal; averaging means for averaging the digital signal; calculation means for calculating drift based on the initial set of coefficients of drift; means for subtracting the calculated drift from the averaged signal; an integrator for integrating the averaged signal less the calculated drift to provide a system output; computation means, responsive to the system output, for computing a new set of coefficients when the angular rate is less than a pre-defined threshold; and means for adjusting the system output in response to the new set of coefficients.
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5. A system for accurately determining the position of a device rotatable about an axis, comprising:
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(a) an angular rate sensor, the sensor having an output; (b) means for mounting the sensor to the device and orienting the sensor to sense rotation of the device; and (c) means for processing the sensor output, comprising; means for reducing noise in the sensor output; and compensation means comprising means for initially adjusting the sensor output for a pre-determined rate of drift; and means for subsequently computing a new rate of drift when the angular rate is less than a pre-defined threshold and adjusting the sensor output in response to the new rate of drift. - View Dependent Claims (6, 7)
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8. A system for accurately determining the azimuth of a rotatable weapon, comprising:
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(a) an angular rate sensor, the sensor having an output; (b) means for mounting the sensor to the weapon and orienting the sensor to sense rotation of the weapon; and (c) means for processing the sensor output, comprising; i) means for calibrating the sensor output, the means for calibrating including an analog-to-digital converter for converting the sensor output to a digital signal; averaging means for averaging the digital signal; an integrator for integrating the averaged signal; and curve-fitting means, responsive to the integrated signal, for determining an initial set of coefficients of drift through a least-squares curve-fit method; and ii) means for determining the angular movement of the sensor, the means for determining the angular movement including an analog-to-digital converter for converting the sensor output to a digital signal; averaging means for averaging the digital signal; calculation means for calculating drift based on the initial set of coefficients of drift; means for subtracting the calculated drift from the averaged signal; an integrator for integrating the averaged signal less the calculated drift to provide a system output; computation means, responsive to the system output, for computing a new set of coefficients when the angular rate is less than a pre-defined threshold; and means for adjusting the system output in response to the new set of coefficients.
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9. A method of processing the output of an angular rate sensor, comprising the steps of:
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reducing noise in the sensor output; and compensating for drift, the step of compensating comprising the steps of initially adjusting the sensor output for a pre-determined rate of drift; and subsequently computing a new rate of drift when the angular rate is less than a pre-defined threshold and adjusting the sensor output in response to the new rate of drift. - View Dependent Claims (10, 11)
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Specification