Research On Satellite Nozzle Docking Device And Capture Strategy

With the progress and development of space science and technology,more and more artificial satellites are launched into space.In space,a large number of satellites need to be maintained.A lot of space junk needs to be cleaned up.More valuable space resources need to be protected.Human being urgently need to master the technology of on-orbital service.Autonomous capture technology to non-cooperative target in space is the premise and key technology to carry out on-orbital service.This thesis studies the docking device and the capture nozzle strategies based on satellite capture.Satellite nozzle docking device is used to capture non-cooperative satellite installed nozzle.These satellites,taking up valuable orbit resources and very expensive,run mainly in the geostationary orbit or high orbit.Capturing these satellites for on-orbital service obtains significant economic benefits but also protects orbit resources.The largest tolerance probe–drogue docking mechanism and berthing operations scenario are adopted to capture the satellite from the inner surface of satellite nozzle to achieve docking with a space non-cooperative satellite.The docking device is developed base on capturing satellite nozzle,including locking system,sensors system and electrical system.Locking mechanism of locking system is developed in order to achieve capture and lock the satellite nozzle throat structure.The correctness of the design is verified by simulation and experiment.The contact shell of docking device is developed.Microminiature laser range finders are developed for pose measurement of satellite nozzle.The sensors system of docking device consists of the laser range finders,six-axis force / torque sensor,position sensors,a miniature surveillance camera and sensors inside the motor-driven system.The electrical control system of docking device is developed based on FPGA.Annular electrical circuits are developed to achieve electromechanical control integrated design.Docking device can measure the nozzle position and orientation after entering satellite nozzle at very close range.The laser range finders are reasonably arranged.Pose measurement algorithm is developed to make docking device autonomously measure non-cooperative satellite.Pose measurement principle based on laser ranging is analyzed.Double planes and emission in radiation shape(SDDPER)is introduced.The relative pose of revolution surface can be measured based on SDDPER configuration.In order to avoid the calculations of complicated nonlinear implicit transcendental equations,GAA method is proposed for real-time calculation of the relative pose of revolution surface.Characteristics of GAA Method is analyzed.Its effectiveness is verified by experimental methods.Pose measurement is implemented after docking device entering satellite nozzle at very close range.Non-contact capture potential field method is developed on the basis of laser range finders and the nozzle pose measurement.Based on artificial potential field method,a capture potential field method of coordinate directions anisotropy is proposed.Specified motion capture trajectory is impemented by the capture potential field.The role of the capture potential field are as following: adjusted simultaneously the position and orientation,collision avoidance by capture trajectory based on anisotropy in different cooridinate directions,changeable moving speed in the capture process,making the locking mechanism pass through and lock the nozzle throat structure to aviod collision and stuck phenomenon,priority adjusted coaxial position error and orientation error based on nozzle structural characteristics.Capture potential field method is analyzed and validated by computer simulation and experimental methods.Capture potential field method combines admittance control strategy,speed strategy and searching strategy.The different strategies are chosen depending on the results of sensor measurements.The capture strategy is completed for capturing satellite nozzle.Ground hardware-in-the-loop(HIL)testbed based on robots is set up.On this testbed,experiments are carried out,including pose measurement based on laser ranging,capturing nozzle based on capture potential field method and demonstrations based on capture strategies.The experiments show the validity and efficiency of study contents.The satellite nozzle docking device can capture and lock nozzle.The pose measurement method based on laser ranging can effectively measure the nozzle pose.The capture trajectory of power function is planned by capture potential field method for capturing nozzle.The overall capture strategy is designed for capturing satellite nozzle.