Identification of Relative Position of Two Objects in Space Using Image Processing

Determination of relative position between two objects is an important task during space activities like automated space rendezvous and docking. The relative orientation measured in terms of six Degree of Freedom (6DOF) vector. The six Degree of Freedom vector can be determined by using a sensor system consists of a passive reflective pattern on the target vehicle, imaging this reflective pattern using two Charge Coupled Device (CCD) cameras mounted on the chaser vehicle, illuminating the target pattern using an array of laser diodes and other image processing units. This paper contains a brief description of the sensor system and the algorithm for determination of relative state vector between two objects using five spot passive reflective target patterns. The algorithm starts with measurement of azimuth and elevation angles from the camera image. Then the ranges to each spot in the target pattern can be measured. Finally the rotational angles yaw, roll and pitch are determined using QUEST algorithm.