A vision system for autonomous satellite grapple with attitude thruster

This paper describles an experiment of a binocular vision-based system for positioning the thruster nozzle on the satellite mockup. Images of the thruster are obtained using two cameras in order to determine the thruster's 3D position. At the beginning the thruster is selected manually, and then a local image region is extracted from the raw image. Subsequently, a Canny detector algorithm is used in the local image region to acquire the edge roadmap, and a Hough Transform algorithm is performed to detect the features with circles. Then, a curving fitting method is employed to determine the position of the center of the thruster nozzle., The end effector keeps tracking the target thruster to the distance of 0.1 meter and grasps the target by prodicting its trajectory. The experiment has shown that the system is robust to camera/target relative motions and performs approaching and grappling procedures on satellite mockup successfully.