Research On Impact Dynamics Of Rigid-flexible Coupled Flexible Manipulator

Due to the limitation of launch cost and carrying capacity,space manipulator is a kind of flexible robot which is made up of slender and light rods in space,the flexible deformation of the structure can not be ignored.In the process of large-scale motion,the flexible manipulator will vibrate,and when the target is captured,the dynamic characteristics of the flexible manipulator will be changed due to the impact force and its flexible deformation.In this thesis,the modeling theory of flexible manipulator and the modeling method of Impact Dynamics are studied,and the related theories are applied to the modeling of Impact Dynamics of multi-link flexible manipulator.In this thesis,a rigid-flexible coupling dynamic model is established by using the assumed mode method to discretize the flexible manipulator,and a simplified dynamic model which neglects the axial tension and compression deformation is compared,the results show that there is no difference in the dynamic characteristics between the primary model and the primary model.Based on a simplified model,the forward Impact dynamics of a flexible manipulator is studied.In this thesis,impulse-momentum method,continuous contact method and contact constraint method are studied.The difference and dynamic characteristic of different Impact modeling methods of flexible manipulator are found.Furthermore,the influence of material distribution index of FGM flexible manipulator on the impact dynamics is studied.Secondly,based on the theory of forward Impact dynamics modeling and the condition of trial and error judgment,a friction modeling method is proposed to deal with the different characteristics of the three forward Impact modeling methods.The concept of viscous impulse potential is proposed in impulse-momentum method and its dynamic characteristics are studied.In the continuous contact method,a method is proposed to solve the tangential viscous friction according to the kinematic conditions and the dynamic characteristics are compared with the general smoothing model.According to the initial condition ?t ?0,an impulse-momentum method is proposed to solve the contact constraint problem,which takes into account the initial conditions of slip and viscosity.Then,two modeling methods based on LuGre model with dynamic friction are proposed,and the dynamic characteristics of the model are compared with that of Coulomb model with contact constraint.In the study of complementary algorithm modeling for contact constraint method,the initial conditions can be solved by complementary algorithm of stepping impulse method,in the calculation of continuous Impact force and friction force,a complementary algorithm model considering the maximum static friction is established according to the related theory.Finally,according to the dynamic modeling theory with friction,a general dynamic equation of multi-link flexible manipulator with high-order rigid-flexible coupling is established by combining the recursive idea of D-H method,the Impact problem of multi-link flexible manipulator with friction is modeled and simulated.