Method and apparatus for adaptive filter based attitude updating
First Claim
Patent Images
1. A method, comprising the steps of:
- determining an acceleration mode;
adapting a filter with parameters matching the determined acceleration mode; and
applying the adapted filter to a correction value to determine an estimated error.
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Abstract
A six state Kalman filter is adapted based on a current acceleration mode of an INS device. Gyro measurements are used to determine the acceleration mode and the Kalman filter estimates bias and small angle error of the measurements based on the acceleration mode. The bias error corrects the gyro measurement and the small angle error is used along with the corrected gyro measurement to update an attitude sensed by the gyro.
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Citations
51 Claims
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1. A method, comprising the steps of:
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determining an acceleration mode;
adapting a filter with parameters matching the determined acceleration mode; and
applying the adapted filter to a correction value to determine an estimated error. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method, comprising the steps of:
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determining an acceleration mode;
adapting a Kalman filter with parameters consistent with the determined acceleration mode; and
applying the adapted Kalman filter to a correction value to determine an estimated error of an inertial navigation device;
wherein;
the correction value comprises a difference between a measured inertia value of the inertial navigation device and a predicted inertia value;
the determined acceleration mode comprises one of a non-acceleration mode, a low acceleration mode, and a high acceleration mode; and
the parameters comprise non-acceleration Kalman filter parameters when the determined acceleration mode is the non-acceleration mode, the parameters comprise low acceleration Kalman filter parameters when the determined acceleration mode is the low acceleration mode, and the parameters comprise high acceleration Kalman filter when the determined acceleration mode is the non-acceleration mode. - View Dependent Claims (9, 10)
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11. An attitude determination device, comprising:
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an inertial measurement device;
an error estimator configured to produce an estimated error of the inertial measurement device; and
an attitude update device configured to update an attitude based on measurements from the inertial measurement device and the estimated error;
wherein the estimated error is based on a relationship that relates a dynamic model of error of the inertial measurement device and a measurement model of the inertial measurement device to the estimated error. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method, comprising the steps of:
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measuring at least one inertia based force acting on a body;
identifying a set of parameters that define operation of a characteristic model under the measured inertia;
applying the set of parameters to the model; and
determining the characteristic under the measured inertia from the model. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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38. A six state dynamic model, comprising:
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an input mechanism configured to retrieve small angle and bias information;
a dynamic model comprising a 3 axis small angle rotation vector and a 3-axis bias error defined as wherein δ
ρ
is the 3-axis small angle rotation error vector defined as δ
ρ
=[ε
N,ε
E,ε
D]T and xg is the 3-axis bias error being the small rotation angle error vector, and xg=[gx,gy,gz]T; and
a processing device configured to calculate the model to produce δ
x. - View Dependent Claims (37, 39, 40, 41)
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42. An adaptive filter, comprising a set of states for estimating errors;
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a time transition matrix for updating the states; and
an adaptive update mechanism configured to adapt operation of the time transition matrix based on an operational mode of the adaptive filter. - View Dependent Claims (43, 44, 45, 46, 47)
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- 48. An adaptive filter configured to determine gyro and bias errors for use in an inertial device comprising 3 gyroscopes wherein the adaptive filter has at least six states comprising three tilt angles detected by the gyroscopes and a bias error for each gyroscope and the adaptive filter includes at least three adaptive states including a no acceleration mode, a low acceleration mode, and a high acceleration mode.
Specification