Vision Measurement for the Pose of Cannon Barrel

The pose measurement of cannon barrel (vertical angle and azimuth angle) is a difficulty and emphasis in the precision analysis of SPAAG fire control system. To solve this problem, this paper presents a contactless measuring method based on computer vision. Before measurement, fix a checked planar faceplate on the cannon barrel as a marker. Firstly, get the coordinate of X corner points using Harris Corner Detection Algorithm to calibrate the camera, and chalk up the cameras intrinsic parameters based on Extended Kalman Filter. Secondly, get the corner points from the image of test position, then calculate the extrinsic parameter matrix of the corresponding position combining with LSE algorithm. Finally, according to the motion model of cannon barrel and the position relative to the marker, derive the constraint equations between extrinsic parameter and vertical angle and azimuth angle, then figure out the two angles. Experiment validate the maneuverability and veracity of this method, and the results indicate that the measuring precision of this method is less than 1mil.