Terrestrial land air and sea navigation system

A process comprising:

• setting an initial state position and angular position for a vehicle;
• receiving a measured change in velocity for the vehicle and a measured change in angular rate for the vehicle based on data from an inertial measurement unit;
• receiving a measured magnetic field from a magnetometer for the vehicle;
• determining an estimated position based on the change in velocity or angular rate;
• determining an expected magnetic field measurement based on the estimated position;
• determining a difference between the measured magnetic field from the magnetometer and the expected magnetic field measurement;
• and
• determine a state estimate of the vehicle utilizing an optimal reduced state estimate (ORSE) filter to update a time propagation of state and covariance with a measurement update of the state and covariance;
• wherein the measured change in velocity, the measured change in angulate rate, and the measured magnetic field are transformed from a vehicle reference frame to an Earth-centered inertial reference frame for the ORSE filter in accordance with at least one transform factor for the vehicle.

A vehicle navigation system comprising:

• an inertial measurement unit comprising one or more gyros and one or more accelerometers, the inertial measurement system configured to determine, for a sensor platform, one of an absolute velocity and an absolute angular rate or a change in velocity and a change in angular rate;
• a magneto-optical defect center magnetometer configured to measure a magnetic field;
• and
• a processing system comprising an optimal reduced state estimate (ORSE) filter and configured to:
• determine an estimated position of the sensor platform based on data received from the inertial measurement unit,
• determine an expected magnetic field measurement for the sensor platform based on the estimated position,
• determine a difference between the measured magnetic field from the magnetometer and the expected magnetic field measurement, and
• determine a state estimate of the sensor platform using the ORSE filter by updating a time propagation of state and covariance with a measurement update of the state and covariance,
• wherein the processing system is configured to transform the measured magnetic field from a sensor platform reference frame to an Earth-centered inertial reference frame for the ORSE filter in accordance with at least one transform factor for the sensor platform,
• wherein the ORSE filter measurement noise matrix accounts for alignment bias, wherein an enhanced magnetic model (EMM) map is parameterized with respect to inertial coordinates.

A vehicle navigation system comprising:

• means for determining one of an absolute velocity and an absolute angular rate or a change in velocity and a change in angular rate of a sensor platform;
• means for measuring a magnetic field;
• and a processing system comprising:
• means for determining a difference between the measured magnetic field and the expected magnetic field measurement, and
• means for determining a state estimate of the sensor platform by updating a time propagation of state and covariance with a measurement update of the state and covariance;
• wherein the processing system is configured to transform the measured magnetic field from a sensor platform reference frame to an Earth-centered inertial reference frame for the means for determining the state estimate in accordance with at least one transform factor for the sensor platform.