| The automatic docking and assembling technology is an effective means to realize the automatic docking assembly,the high-mobility of erection,folding and transfer of large array radar antennas at battlefields to improve the battlefield support and survivability of radar systems.The hybrid serial-parallel mechanism integrating the advantages of large workspace in the serial mechanism and large load capacity,high precision and high rigidity in the parallel mechanism,with diverse combinations of structure modes,convenient arrangement for vehicle transportation,is a new attitude adjustment mechanism suitable for the automatic docking system of large radar antenna.In this paper,a novel 6-DOF hybrid serial-parallel mechanism used for pose adjustment applied to the automatic docking system of radar antenna will be studied in aspects of kinematics,mechanism dexterity,workspace characteristics,dynamics and stiffness characteristics with methods of theoretical modeling and simulation analysis,so as to lay a theoretical foundation for the engineering design and applications of this configuration hybrid mechanism.Firstly,according to the characteristics of the automatic docking tasks of large radar antenna,the overall configuration design and analysis of the 6-DOF hybrid mechanism used pose adjustment were carried out.The overall kinematic model of the hybrid mechanism was established by using position vector method and homogeneous coordinate transformation theory,and the simulation verification of overall kinematic model was carried out in Adams.Based on the theoretical model,the kinematic characteristics of the mechanism under different working conditions were analyzed.Then on the basis of the established kinematic model,the velocity vector method was used to analyze the speed of each motion platform of the mechanism,and the overall speed Jacobian matrix of the hybrid mechanism was established,and simulation verification of the overall Jacobian matrix was performed in Adams.Based on the kinematic model and the overall Jacobian matrix,the influence of the main structural scale parameters of the mechanism on its dexterity and working space range characteristics was studied,and the workspace characteristics of the hybrid mechanism under different working conditions were analyzed with examples.Then the vector method was used to analyze the linear and angular velocities of each driving branch chain.Six independent parameters describing the kinematics of the hybrid mechanism were selected as its generalized coordinates.Combined with the overall speed Jacobian matrix of the hybrid mechanism,the dynamic analysis of the driving branches and motion platforms in the hybrid mechanism carried out with Lagrange method,the overall closed dynamic model of the hybrid mechanism was established,and the driving force of the mechanism under different working conditions was simulated and analyzed.Finally,based on the overall speed Jacobian matrix of the hybrid mechanism,the static transfer matrix and the deformation transfer matrix including constraints were analyzed through appling the velocity constraint equation at the end of the mechanism and the principle of virtual work,and the full stiffness models of each layer of the pose adjusting mechanism and the 6-DOF hybrid mechanism were established.Based on the full stiffness models,the stiffness characteristics in six directions and the maximum and minimum stiffness characteristics of the mechanism with the change of key dimension parameters and its distribution characteristics in the working space were simulated.The force characteristics of the hybrid mechanism in the application process were analyzed. |
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