TIGHTLY-COUPLED GNSS/IMU INTEGRATION FILTER HAVING CALIBRATION FEATURES
First Claim
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1. An apparatus comprising:
- an integration filter for a sensor-assisted global navigation satellite system (GNSS) receivera GNSS measurement engine for providing GNSS measurement data to said integration filter;
an inertial measurement unit (IMU); and
an inertial navigation system (INS) block for calculating INS navigation information using a plurality of inertial sensor outputs,wherein said integration filter performs a blending operation for combining said GNSS measurement data and said INS navigation information, and for estimating and compensating a speed bias and a heading bias.in the INS measurement.
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Abstract
Embodiments of the invention provide a blending filter based on extended Kalman filter (EKF), which optimally integrates the IMU navigation data with all other satellite measurements (tightly-coupled integration filter). Two more states in the EKF for estimating/compensating the speed bias and the heading bias in the INS measurement are added. The integration filter has no feedback loop for INS calibration, and can estimate/compensate the navigation error in the INS measurement within the integration filter.
23 Citations
26 Claims
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1. An apparatus comprising:
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an integration filter for a sensor-assisted global navigation satellite system (GNSS) receiver a GNSS measurement engine for providing GNSS measurement data to said integration filter; an inertial measurement unit (IMU); and an inertial navigation system (INS) block for calculating INS navigation information using a plurality of inertial sensor outputs, wherein said integration filter performs a blending operation for combining said GNSS measurement data and said INS navigation information, and for estimating and compensating a speed bias and a heading bias.in the INS measurement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of calibration comprising:
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creating a coordinate transformation matrix using a latest position fix (latitude and longitude); transforming said state variables (for user velocity) to a local navigation coordinate using said coordinate transformation matrix; including a plurality of INS measurements in said local navigation coordinate in a measurement equation in a way that said INS measurements are a function of a plurality of velocity variables and speed and/or heading bias variables of an integration filter state with a plurality of measurement noises; estimating said state variables (which include speed bias and/or heading bias) of said integration filter. outputting a blended calibrated position fix. - View Dependent Claims (19, 20, 21, 22, 23)
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24. A method of calibration comprising:
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creating a coordinate transformation matrix using a latest position fix (latitude and longitude); transforming said state variables (for user velocity) to a local navigation coordinate using said coordinate transformation matrix; including a heading measurement using an angle of said INS velocity vector on horizontal navigation plane; estimating said state variables (which include speed bias and/or heading bias) of said integration filter. outputting a blended calibrated position fix.
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25. A method of calibration comprising:
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creating a coordinate transformation matrix using a latest position fix (latitude and longitude); transforming said state variables (for user velocity) to a local navigation coordinate using said coordinate transformation matrix; including a speed measurement using a magnitude of an INS velocity vector on horizontal navigation plane; estimating said state variables (which include speed bias and/or heading bias) of said integration filter. outputting a blended calibrated position fix. - View Dependent Claims (26)
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Specification