Dynamic Modeling And Control Of Space Manipulators Based On Axis-Invariant

As space manipulator has important auxiliary functions for space missions,its research is one of the important aspects in the development of space technology.Space manipulators must possess the features of heavy payload,high positioning accuracy,autonomy and real-time performance,etc.On the basis of the existing theory,structure selection,construction and solution of dynamics models,and Force-Position control for space manipulators are studied in this work.As a result,a set of software for dynamic simulation is developed.Firstly,the general design of the 6-DOF space manipulator studied in this paper is presented.The selection of motor and reducer meets the functional requirements of the space manipulator.The concepts of Nature Frame and Axis-Invariant are introduced in the investigation of the designed space manipulator based on which the structure parameters of the manipulator are set.Secondly,the rotation transformation matrix and the motion parameters between the axes are obtained via the kinematic model of the manipulator.Meanwhile,the dynamic equations of the manipulator based on Axis-Invariant are established by using Ju-Kane method.The model has an elegant and concise symbol system of chain-ordering and low computational complexity,which can meet the requirement of accuracy and real-time performance of the system.Thirdly,the application of the dynamics model in Force-Position control of a manipulator is presented.A robust model predictive control method is used to control the rotation angles of each axis by controlling the output torque of each joint when there is no contact with the environment.If the manipulator is in contact with the environment,the position based impedance control is employed to control the contact force between the manipulator and the environment,and the goal of compliance control of the manipulator is achieved.Based on the above study and research,a software for simulation of dynamic system is developed by using C++ language in combination with MFC,Open Inventor and other libraries.The model of the space manipulator is imported the software,and the dynamic test and the Force-Position control simulation is carried out.The simulation experiments have verified the validity of the Ju-Kane method and the effectiveness of the control algorithm.