Image-augmented inertial navigation system (IAINS) and method
An image-augmented inertial navigation system (LAWS) mounted on a vehicle ( 10 ) includes an inertial navigation system (INS) configured to estimate a navigation state vector and an imager ( 12 ) configured to output pixel signals associated with terrain features passing through a field of view (x, y, z) of the imager. The system (IAINS) further includes a processing unit operatively connected to the inertial navigation system (INS) and the imager ( 12 ). The processing unit is configured to sense a distance from the imager to a centroid of one or more of the terrain features passing though a field of view of the imager for a given image frame associated with the feature pixel signals. The processing unit is also configured to track each terrain feature as the terrain features pass through the field of view of the imager. The processing unit is further configured to update the navigation state vector of the inertial navigation system (INS) based on calculated NED (North, East, Down) coordinates position information of the inertial navigation system (INS) relative to the tracked terrain features.
1. An image-augmented inertial navigation system comprising:
an inertial navigation system configured to estimate a navigation state vector;
an imager configured to output pixel signals associated with terrain features passing through a field view of the imager over a plurality of image frames; and
a processing unit operatively connected to the inertial navigation system and the imager, the processing unit being configured to
sense a distance from the imager to a centroid of one or more of the terrain features passing through the field of view of the imager for a given image frame based on the pixel signals,
track each terrain feature from a first image frame containing the terrain feature to any subsequent image frame while the terrain features remain within the field of view of the imager,
calculate NED coordinates position information of the inertial navigation system relative to first tagged coordinates of each tracked terrain feature, and
update the navigation state vector of the inertial navigation system based on the calculated inertial navigation system position information.
2. The system of claim 1 , wherein the processing unit is configured to track new terrain features as they pass within the field of view of the imager by determining the distance between the imager and the new terrain features and by predicting a distance between the new terrain features and the imager based on a current known location of the inertial navigation system.
3. The system of claim 1 , wherein the processing unit is configured to determine and tag NED coordinates position information for new terrain features a first time the new terrain features enter into the field of view of the imager, based on the current inertial navigation system position, range to the new terrain feature, orientation and offset of the imager with respect to the inertial navigation system.
4. A vehicle comprising the system of claim 1 .
5. A method of updating a navigation state vector of an inertial navigation system associated with a vehicle, the method comprising:
sensing a distance from an imager associated with the vehicle to a centroid of one or more terrain features passing through a field of view of the imager for a given image frame;
tracking each terrain feature from a first image frame to a subsequent image frame as the terrain features pass through the field of view of the imager;
calculating NED coordinates position information for each of the tracked terrain features; and
updating the navigation state vector of the inertial navigation system based on the calculated NED coordinates position information.
6. The method of claim 5 , further comprising tracking new terrain features as they pass within the field of view of the imager by determining the distance between the imager and the new terrain features and by predicting a distance between the new terrain features and the imager based on a current known location of the inertial navigation system.
7. The method of claim 5 , further comprising determining and tagging NED coordinates position information for new terrain features a first time the new terrain features enter into the field of view of the imager based on a current inertial navigation system position, range to the terrain new feature, orientation and offset of the imager with respect to the inertial navigation system.