Pose Estimation of Large Non-cooperative Spacecraft Based on Extended PNP Model

The space robotic system is expected to perform the on orbit servicing mission. It is a challenging task to estimate the pose of the non-cooperative spacecraft (no facilities are mounted onboard for relative pose measurement) during the phase of closing, capturing, and maintenance. In addition, the spacecraft with a high value is always very large, which pose difficulties for the cameras to photo the whole scene in close range. This paper propose a new approach using combined vision system to estimate the relative position and attitude of a large non-cooperative spacecraft in close range. Based on investigation of the characteristics of spacecraft, a series of the feature point is selected as the recognized object. Then, rendezvous camera and eye-in-hand camera share the recognition task in a collaborative behavior, i.e. each traces one or two feature points on the target. In order to fuse the information, an extended PnP model is established. Lastly, the pose estimation algorithm by solving the extended PnP problem is addressed. Results of computer simulation validate the proposed approach.