Gyroscope noise reduction and drift compensation
AssigneeAlliedSignal Inc.
InventorsPei-hwa Lo, Peter Halatyn, Eric Geoca, James B. Archibald
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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.
Claims11
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 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.
A system for processing the output of an angular rate sensor, comprising:
- (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.
A system for accurately determining the position of a device rotatable about an axis, comprising:
- (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.
A system for accurately determining the azimuth of a rotatable weapon, comprising:
- (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.
A method of processing the output of an angular rate sensor, comprising the steps of:
- 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.
Dependencies are inferred from the claim text.