Navigation system for a vehicle, especially a land craft
First Claim
1. In a navigation system for a vehicle of the type having at least one single-axis gyro for the vehicle vertical axis z, and x and y axis accelerometers in the horizontal vehicle plane, a vehicle-fixed velocity measurement device and an augmentation device, especially at least one of satellite navigation receiver or a map device, for augmenting position or velocity of the vehicle or both and a controller for correcting at least one of the calculated vehicle position and direction of travel via a suitable Kalman filter using measured signals supplied from said augmentation device comprising, in combination:
- a) a Kalman filter partitioned into at least a first partial filter for dynamic levelling; and
b) and a second partial filter designated as a position filter for providing track calibration, position calibration and sensor calibration.
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Accused Products
Abstract
The invention relates to a navigation system for a vehicle, in particular for a land vehicle, having at least one single-axis gyro for the vehicle vertical axis (z axis), having two accelerometers in the horizontal vehicle plane (x axis, y axis), and having a vehicle-axis velocity measurement device, for example, a distance-travelled sensor. In addition, supporting signal devices, in particular a satellite receiver and/or a map, are available as well as a controller, which uses a suitable Kalman filter to determine the vehicle position and/or the direction of travel from the measured and stored signals. The Kalman filter is assigned at least one partial filter, of which a first partial filter is used for dynamic levelling and/or a second partial filter is designed as a position filter which provides track calibration, position calibration and sensor calibration.
104 Citations
16 Claims
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1. In a navigation system for a vehicle of the type having at least one single-axis gyro for the vehicle vertical axis z, and x and y axis accelerometers in the horizontal vehicle plane, a vehicle-fixed velocity measurement device and an augmentation device, especially at least one of satellite navigation receiver or a map device, for augmenting position or velocity of the vehicle or both and a controller for correcting at least one of the calculated vehicle position and direction of travel via a suitable Kalman filter using measured signals supplied from said augmentation device comprising, in combination:
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a) a Kalman filter partitioned into at least a first partial filter for dynamic levelling; and
b) and a second partial filter designated as a position filter for providing track calibration, position calibration and sensor calibration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
a) said partial filter for dynamic levelling being arranged to carry out rotation rate estimation in the vehicle-fixed horizontal plane; and
b) said estimated values obtained being fed back almost continuously to said navigation system.
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3. A navigation system as recited in claim 2 further including means for providing that said estimated values are fed back with a suitable bandwidth for a predetermined application.
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4. A navigation system as recited in claim 2 further including means for providing that estimated values equivalent to the rotation rate estimated values are fed back.
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5. A navigation system as recited in claim 4 further including means for providing that estimated values of the discrete angular increments in said horizontal vehicle x and y agues are fed back.
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6. A navigation system as recited in claim 2 wherein the order of the partial filter matches a definition of the error states.
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7. A navigation system as recited in claim 6, characterized in that the partial filter for dynamic levelling is based on a discrete sixth order error model formulated as follows:
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8. A navigation system as recited in claim 1 characterized in that:
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a) said partial filter for dynamic levelling comprises two stationary third order Kalman filters; and
b) couplings between said third order partial filters comprise deterministic input signals.
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9. A navigation system as recited in claim 8 characterized in that said partial filter for dynamic levelling is integrated in said Kalman filter.
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10. A navigation system as recited in claim 1 characterized in that the stochastic model in the Kalman filter is adaptive, having frequency-band-selective assessment of the translational disturbances in the acceleration measurements.
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11. A navigation system as recited in claim 1 further including:
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a) means for checking the probability of supporting positions used in said second partial filter, designed as a position filter; and
b) means for resetting said position filter to a defined status using stored and verified sensor calibration values if the augmentation positions are not probable.
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12. A navigation system as recited in claim 11 further including means for setting the position filter to default status when said position filter is first switched on.
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13. A navigation system as recited in claim 11 further including means for azimuth monitoring.
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14. A navigation system as recited in claim 13 further including:
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a) means for performing statistical error assessment steps for said plausibility check and said azimuth monitoring; and
b) said statistical error assessment means employs said covariance information calculated in said Kalman filter for said filter estimated parameters as self diagnosis.
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15. A navigation system as recited in claim 11 further including:
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a) means for carrying out an unaided control navigation calculation in addition to said aided navigation calculation; and
b) means for matching said unaided control navigation calculation to said aided navigation calculation at each control point; and
c) means for using said stored and verified sensor calibration values from the last control navigation calculation that did not lead to said resetting of said position filter.
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16. A navigation system as recited in claim 11 further including:
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a) means for performing a position filter changeover when an algorithm detects said vehicle is stationary; and
b) said last-named means includes means for connecting a measured value from a z gyro as observations to said Kalman filter.
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Specification