Research On The Structure Design And Control Of The Telescopic Space Manipulator

For the on orbit assembly of space telescope,there are many assembly processes,various working positions and high precision requirements.The telescopic space manipulator can change the length of the manipulator through telescoping,to adapt to the change of telescope diameter,and to solve the problem of space manipulator transportation.First of all,according to the specific design index of the project,this paper completed the structural design of the telescopic space manipulator.A passive expansion and active locking expansion scheme is adopted,and the crank slider mechanism is introduced into the locking device.The dynamic simulation analysis of the locking scheme is carried out by Adams.And it verifies that the scheme can effectively reduce the driving torque of the locking movement and the reverse torque of the locking device under the working condition of the mechanical arm.And using the simulation and calculation data to select the corresponding electrical components,harmonic drive.In this paper,the energy of boom expansion is used to drive the retractable device of wire.And the scissor mechanism is innovatively improved,which is applied to the retractable device of wire to ensure the fixation and own security of conductor.And through the finite element analysis,the stiffness and strength of the whole arm and key components are checked.After that,the trajectory planning of the manipulator is carried out.The telescopic motion is simplified into three joints and two telescopic arms.The kinematics of the arm is analyzed,and the quintic polynomial method is selected to plan the trajectory in the joint space,which meets the requirements of continuous acceleration and avoids the vibration and impact of the driving joint in the start and stop state.Through simulation,the angular displacement,angular velocity and angular acceleration of each joint meet the performance requirements of the joint.The control of stretching movement is studied.The joints are divided into active joints and passive joints.For the active joint,PD control is adopted.For the passive joints,impedance control is adopted.The friction model is studied and the corresponding friction compensation function is obtained.Finally,the forward kinematics of the complete 7-DOF manipulator is analyzed.And the change of its working space is confirmed to meet the design requirements.The Adams dynamic model is established to verify the control effect.The comparing whether the impedance control is increased or not is made.The comparison between impedance control based on torque and impedance control based on position is made.The simulation results show that the simulation scheme is correct.