초록 ▼

Concurrent determinations of errors for application of corrections to sensor data signals from an orbiting space vehicle to reduce or to eliminate the three components of boresight error. To locate more accurately the geographical position of targets detected by the sensors of an orbiting satellite,

Concurrent determinations of errors for application of corrections to sensor data signals from an orbiting space vehicle to reduce or to eliminate the three components of boresight error. To locate more accurately the geographical position of targets detected by the sensors of an orbiting satellite, the pitch, roll, and yaw boresight errors caused by distortions or misalignments in the focal plane of the sensors are compensated for by comparing known position coordinates of an object (such as a star) to the observed position coordinates. The known position coordinates are converted to sensor coordinates by a series of intermediate coordinate conversions, essentially from the celestial frame of reference to an earth-centered frame of reference to a satellite attitude frame of reference to the satellite frame of reference to the sensor frame of reference. The corrections are applied frequently enough to take into account the change of the satellite's position relative to the sun to compensate for the thermal effects, inter alia, causing the boresight error. An optimal estimator increases the accuracy of the results.

대표청구항 ▼

[ What is claimed is:] [1.] In a spacecraft imaging system, a boresight correction system comprising, in combination:an array of a plurality of sensing elements for producing signals indicative of an imposed image thereon;means for predicting the position of a known image in terms of given ones of s

[ What is claimed is:] [1.] In a spacecraft imaging system, a boresight correction system comprising, in combination:an array of a plurality of sensing elements for producing signals indicative of an imposed image thereon;means for predicting the position of a known image in terms of given ones of said sensing elements;means for determining a sensing element receiving the known image imposed on said array;spacecraft attitude determining means;means responsive to the predicting means, to the spacecraft attitude determining means, and to the sensing element determining means for supplying error signals representative of the differences between the actual locations and predicted locations of said images on the array; andestimator means for supplying best-estimate correction offsets to be applied to observation data from said array of sensing elements.