Pose measurement of nozzle based on laser range finders for capturing satellite

Sensors system is considered as one of the most indispensable devices to the mission of capturing a satellite for on-orbit servicing in the space. In this paper, in order to measure the pose of nozzle, six laser range finders are installed in the capturing nozzle device for entering into and capturing nozzle, and a Geometric Axis Approximation (GAA) method is proposed to estimate the pose of satellite nozzle. Six laser range finders are arranged in the configuration of emission radiated at two planes of top and bottom. The pose measurement system is composed of the six laser range finders, applicable for real-time measurement of the ranges from inner surface of nozzle. Based on the properties of nozzle shape and finders arrangement, the GAA method is used to estimate the pose of nozzle by a connecting line between two centers of circles in the top and bottom planes. In the pose estimation of GAA method, solving the nonlinear transcendental equations can be avoided and a simple explicit model is built. Therefore, the GAA method is suitable for real time measurement. In this paper, the theoretical error of GAA method is analyzed, and in the capturing nozzle experiment system, the experiments of pose measurement are carried out. The results of experiments prove the efficiency of GAA method in pose estimation to nozzle based on laser range finders.