Heading inconsistency mitigation for inertial navigation using low-performance inertial measurement units with relative aiding
First Claim
1. A method of mitigating filter inconsistency of a heading estimate in an inertial navigation, the method comprising:
- inputting inertial measurements from at least one inertial measurement unit (IMU) in the inertial navigation system;
inputting an initial-heading from at least one heading-information source;
inputting an initial-heading uncertainty level associated with an error in the inputted initial-heading;
initializing an initial-heading estimate with the inputted initial-heading;
initializing an initial-heading uncertainty estimate with the inputted initial-heading uncertainty level;
initializing an accumulated heading-change estimate to zero at a startup of the at least one IMU;
initializing an accumulated heading-change uncertainty estimate with an initial accumulated heading-change uncertainty level that is a value less than the inputted initial-heading uncertainty level; and
periodically updating the accumulated heading-change estimate with the inertial measurements input from the at least one IMU.
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Abstract
A method of mitigating filter inconsistency of a heading estimate in an inertial navigation system is provided. The method includes inputting inertial measurements from at least one low-performance inertial measurement unit (IMU) in the inertial navigation system; inputting an initial-heading from at least one heading-information source; inputting an initial-heading uncertainty level associated with an error in the inputted initial-heading; initializing an initial-heading estimate with the inputted initial-heading; initializing an initial-heading uncertainty estimate with the inputted initial-heading uncertainty level; initializing an accumulated heading-change estimate to zero at a startup of the at least one low-performance IMU; and initializing an accumulated heading-change uncertainty estimate with an initial accumulated heading-change uncertainty level that is a value less than the inputted initial-heading uncertainty level; and periodically updating the accumulated heading-change estimate with the inertial measurements input from the at least one low-performance IMU.
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Citations
15 Claims
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1. A method of mitigating filter inconsistency of a heading estimate in an inertial navigation, the method comprising:
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inputting inertial measurements from at least one inertial measurement unit (IMU) in the inertial navigation system; inputting an initial-heading from at least one heading-information source; inputting an initial-heading uncertainty level associated with an error in the inputted initial-heading; initializing an initial-heading estimate with the inputted initial-heading; initializing an initial-heading uncertainty estimate with the inputted initial-heading uncertainty level; initializing an accumulated heading-change estimate to zero at a startup of the at least one IMU; initializing an accumulated heading-change uncertainty estimate with an initial accumulated heading-change uncertainty level that is a value less than the inputted initial-heading uncertainty level; and periodically updating the accumulated heading-change estimate with the inertial measurements input from the at least one IMU. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An inertial navigation system with mitigated heading inconsistency, the system comprising:
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at least one processor to execute algorithms in a strapdown navigation module and in a navigation filter to; estimate an initial-heading error using a state that is independent of an estimated error in an accumulated heading-change since a startup of at least one inertial measurement unit (IMU) in the inertial navigation system; estimate an initial-heading error using a first filter error state; estimate an accumulated heading-change error using a second filter error state; wherein the first error state is an independent and distinct error state from the second filter error state; and ensure the first error state and the second error state directly correspond to navigation quantities explicitly computed in the inertial navigation system; and the at least one IMU to input inertial measurement to the strapdown navigation module; at least one relative aiding sensor to input at least one measurement of navigation data to the navigation filter, wherein the at least one relative aiding sensor is unable to directly sense the initial-heading. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification