Study On Dynamic Characteristics Of Space Manipulator With Three-dimensional Clearance Joints

With the rapid development of space technology,the exploration of outer space continues to deepen,and humans have established space stations in space to serve humans and better explore outer space.As one of the important components of the space station on-orbit service,the space manipulator has the characteristics of high accuracy,light weight and low energy consumption.Space manipulator is composed of several arms and connected with each other through motion pairs.In order to ensure the normal relative motion of the arm rod in the microgravity environment,the clearance at the joint of the motion pair is inevitable considering the manufacturing,assembly errors,friction and wear.The existence of the clearance makes the motion of the mechanism uncertain.The collision of the components at the clearance joint may cause the vibration of the mechanism,which affects the trajectory and positioning accuracy of the system,and even causes the system to collapse.In this paper,a three-dimensional collision force model is established at the interstitial joints,and the dynamics of the space manipulator with interstitial joints is analyzed.Firstly,in order to describe the collision process more accurately,based on the two-dimensional collision force model of the clearance joint,the dynamic equation of the space manipulator with clearance joint is established,which considers the threedimensional radial and axial collision factors.A program for calculating the clearance impact force is written in Fortran language,and the calculated impact force is invoked in ADAMS software for simulation analysis.This method can be used to study the influence of multiple clearance joints on the system more conveniently.Secondly,based on the developed simulation module,the crank-slider model is used to verify the correctness of the simulation results when only two-dimensional collision model is considered.The influence of clearance position on the parameters of the space manipulator system,such as position and posture,end movement and impact force,is analyzed when only two-dimensional clearance joint collision model is considered.The influence of clearance size on the dynamic performance of the space manipulator under the coupling action of two-clearance joints is also analyzed.Finally,considering the three-dimensional impact force,the influence of different clearance positions on the dynamics of the space manipulator is analyzed dynamic response of the double clearance joints manipulator system,and the influence of threedimensional radial clearance on the dynamics characteristics of the double clearance joints are analyzed.Analyze the effect of the axial and radial clearance on the dynamics characteristics of the space manipulator,which considers the axial clearance of the joint.The modeling and simulation results of the three-dimensional collision force of the clearance joint show that the three-dimensional gap has a significant impact on the dynamic performance of the space manipulator and the attitude of the satellite.The three-dimensional clearance of the motion pair should be considered when modeling the manipulator,so that more accurate calculation results can be obtained to ensure the motion accuracy and stability of the manipulator.