Determining angular rate for line-of-sight to a moving object, with a body-fixed imaging sensor

Abstract

Apparatus/method estimate LOS rotation, to track, approach, pursue, intercept or avoid objects. Vehicle-fixed imagers approach/recede-from objects, recording image series with background. Computations, from images exclusively, estimate rotation vs. the vehicle, applying the estimate. Preferably, recording/estimating provide proportional navigation; scan mirrors extend strapdown-sensor FOR; applying includes measuring 'range rate over range', exclusively from interimage optical flow, using results to optimize proportional-navigation loop gain; estimating includes evaluating interframe optical flow, preregistering roughly as first approximation, selecting sequence anchor points, and applying a second, finer technique developing output registration that's a coordinate translation, aligning inertial surroundings. The approximation operates optical flow with efficient embedded registration/mapping, applying a homography matrix to nearby imagery. Alternatively, inexpensive low-quality inertial sensors establish preregistration, deriving a homography matrix. When contrast in the object direction is inadequate, dual sensors yield accurate virtual imaging with an object centroid superposed into background.