Research On Automatic Docking Technology Of Spacecraft Cabins Based On Hybrid Six-degree-of-freedom Attitude Adjustment Mechanism

Spacecraft module docking assembly is an important part in the production process of spacecraft products.The traditional docking method uses professional fixed tooling,which is kind of manual docking assembly after trial assembly.Manual docking assembly has some shortcomings,such as poor assembly consistency,low docking efficiency,long assembly cycle and high labor intensity,that let it uneasy to meet actual production needs under rapid development.For the reasons above,this thesis focuses on technologies,like design of the attitude adjustment mechanism,the pose fitting solution,and the trajectory of the attitude adjustment mechanism,in the automatic docking task of the spacecraft cabins.According to requirements of automatic docking assembly tasks,this thesis presents the entire automatic docking system,introduces working principle of each sub-system,elaborates laser tracker measurement theory and coordinate transformation theory.In addition,a set of precision docking device is created,which composes two parallel mechanisms,plane adjustment mechanism and horizontal adjustment mechanism,for automatic docking and assembly tasks of spacecraft cabins.Based on the closed vector method,the mathematical model of the inverse solution of the mechanism position is solved.Besides,in accordance of the inverse mathematical model,the speed Jacobian matrix and the acceleration Hessel matrix are solved to find out the analytical expressions for the velocity and acceleration of each joint.Firstly,the laser tracker is used to measure the target ball installed on the flange of spacecraft cabins because of the even distribution and high accuracy of the flange mounting holes of the spacecraft cabins.Secondly,according to the three-point method,the initial space pose of spacecraft cabins is calculated.Thirdly,the three-point method to solve the pose is applied as the initial value of the damped least squares method to discover accurate pose of spacecraft cabins.Finally,the effectiveness and accuracy of the pose fitting solution model is verified through numerical simulation.This thesis studies construction method of non-uniform quintic B-spline curve,as well as planning the trajectory of the end in docking platform by the non-uniform quintic B-spline curve in Descartes space.Furthermore,an energy consumption model for the mechanism to complete the docking assembly task is formed based on kinematics and dynamics.Considering the kinematics and dynamics constraints,the hybrid attitude adjustment mechanism is used to dock five-fold B-spline trajectory at the end of the platform.After optimization,the energy consumption is reduced to 408.5J,which meets needs of the continuity and smoothness of the displacement,velocity and acceleration curves of each joint.