Adaptive GPS and INS integration system
First Claim
1. A method of integrating inertial navigation system and satellite navigation system data in a tightly coupled architecture by means of a Kalman filter, the satellite navigation data being received on a receiver comprising tracking loops having adaptive bandwidths, comprisingmonitoring the tracking loop bandwidths or modelling them as a function of the receiver measured signal to noise density ratio (c/n0) outputs, and varying the rate of response of the Kalman filter to measurements from the satellite navigation system in response to changes in the tracking loop bandwidths such that correlated measurement noise in the Kalman filter is avoided.
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Abstract
This invention relates to the field of Inertial Navigation Systems (INS) and satellite navigation systems such as the Global Positioning System (GPS) and in particular relates to methods of integrating GPS and INS data in order to provide more accurate navigation solutions. The invention provides a method of improving the accuracy of a tightly coupled integrated INS and satellite radio navigation system in cases where the satellite navigation receiver has adaptive tracking loop bandwidths.
37 Citations
13 Claims
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1. A method of integrating inertial navigation system and satellite navigation system data in a tightly coupled architecture by means of a Kalman filter, the satellite navigation data being received on a receiver comprising tracking loops having adaptive bandwidths, comprising
monitoring the tracking loop bandwidths or modelling them as a function of the receiver measured signal to noise density ratio (c/n0) outputs, and varying the rate of response of the Kalman filter to measurements from the satellite navigation system in response to changes in the tracking loop bandwidths such that correlated measurement noise in the Kalman filter is avoided. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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7. A method as claimed in claim 1, the Kalman filter comprising a Kalman gain matrix having a measurement noise covariance, R, and wherein said measurement noise covariance, R, is divided by an adaption matrix A as claimed in claim 5.
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8. A method as claimed in claim 1, wherein the measurement noise covariance, R, is weighted by multiplying by the time between successive uncorrelated measurements divided by the time between successive measurements.
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9. A method as claimed in claim 1, wherein the satellite navigation system is a Global Positioning System.
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10. A method of integrating inertial navigation system and satellite navigation system data in a tightly coupled architecture by means of a Kalman filter, the satellite navigation data being received on a receiver comprising tracking loops having adaptive bandwidths, comprising
monitoring the tracking loop bandwidths or modelling them as a function of the receiver measured signal to noise density ratio (c/n0) outputs , and modelling time-correlated measurement noise within the Kalman filter explicitly such that the assumed correlation time within the Kalman filter is varied in inverse proportion to the tracking loop bandwidths.
Specification