US 5,894,323 AGranted

Airborne imaging system using global positioning system (GPS) and inertial measurement unit (IMU) data

AssigneeTasc Ltd.

InventorsJames E. Kain, Charles Yates

Life of this patent

Estimating the term…

Loading patent…

Abstract

A remote data collection system, which may be used in a vehicle such as an aircraft or a ground vehicle, includes a directional sensor, such as one or more cameras, for sensing a characteristic of interest and providing sensor data. The system further includes a global positioning system (GPS) receiver for providing GPS data representative of the position of the sensor, an inertial measurement unit (IMU) for providing IMU data representative of the attitude of the sensor, a processing unit and a storage unit. The processing unit determines geographic data referenced to the sensor data in response to the GPS data and the IMU data. The processing unit may utilize an error model to determine IMU errors which may be used in determining the geographic data with high accuracy. The sensor data and the geographic data are stored in the data storage unit for subsequent use. The system may include a stabilized platform on which the sensor and the IMU are mounted. The stabilized platform is rotated about at least one axis of rotation to control the sensing direction of the sensor as the vehicle moves.

Claims17

Dependent claims

An imaging system for use in an aircraft, said imaging system comprising:

a stabilized platform that is carried by the aircraft and is rotatable, relative to the aircraft, about at least one axis of rotation;
a camera system rigidly mounted to said stabilized platform for providing image data representative of a ground survey area, said camera system having a boresight direction;
an inertial measurement unit (IMU) rigidly mounted to said stabilized platform for providing IMU data representative of attitude of said camera system, said IMU having IMU coordinate axes;
a global positioning system (GPS) receiver for providing GPS data representative of position of said camera system;
a processing unit comprising means for generating an IMU error model for use determining attitude errors, means responsive to said IMU data and said IMU error model for providing attitude data that is corrected for said attitude errors, comprising a strapdown navigation routine that propagates position, velocity and attitude of the IMU coordinate axes forward in time using measurements of change in angle, and a transfer alignment Kalman filter that merges the velocity measurement and an output of the strapdownn navigation routine to produce an estimate of the attitude errors in the IMU attitude data, and means responsive to said GPS data, said attitude data and said image data for providing georegistered image data comprising corresponding sets of said image data, said GPS data and said attitude data, wherein each frame of said image data is registered by said GPS data and said attitude data to said ground survey area;
a control unit responsive to said attitude data for rotating said stabilized platform relative to the aircraft about said at least one axis of rotation to control the boresight direction of said camera system during flight;
and
a data storage unit for storing said georegistered image data for subsequent use.

5 more elements

Dependencies are inferred from the claim text.