| With the development of human society and advances in technoligy,space activities are increasingly frequent and have a profound impact on human development.From military installations to civil satellites,the number of aircraft in space on the surface of the Earth has gradually increased.This makes the spacecraft live hard.At present,most of the faulty satellites in space are scrapped,which further exacerbates the growth of space debris.For such a situation,designing an unmanned,automated on-orbit maintenance robot has become a hot research topic in various countries.This article aims to design a dual-arm space robot that can achieve automatic control or remote operation control to complete the on-orbit maintenance task.The main research contents of this dissertation include: designing a dual-arm space robot with two 7-DOF redundant manipulators,based on specific maintenance tasks,conducting position control and impedance control research,and verifying the control method through simulation experiments.This article first established a three-dimensional model of a two-armed space robot.Design a "3-1-3" configuration of a 7-DOF redundant manipulator through D-H parameter method.The specific dynamics parameters were given,and its inverse kinematics solution method was given.Screen and analyse the multiple solutions.Trajectory planning is carried out in the joint space by five degree polynomial to avoid mutation at speed and acceleration levels.Neglecting the influence of gravity,the use of Newtonian Euler method and combined body inertia method simplifies the solution of the dynamic model.For specific on-orbit maintenance tasks,applicable position control methods were studied.For the PD control strategy and calculation of torque control strategy simulation experiments,a number of evaluation indicators are proposed to compare the control effect of the two at different speeds,and the PD control strategy can be satisfied to meet the onorbit maintenance tasks.And for the dual-arm space robot under the PD control mode,the preparatory operation simulation is performed,and the results meet the designed requirements.Then the paper studies the impedance control method of dual-arm space robot.The mapping relationship between the contact force at the end of the arm and the joint was proved.For the task characteristics of the on-orbit maintenance system of the two-armed space robot,an impedance model was established,which can be effectively used to achieve impedance control during maintenance operations.In order to solve the problems such as the satellite attitude deviation and the incompatibility of the two-arm internal force that may occur when the on-orbit maintenance system performs the linear feed cutting task,a synchronous impedance control method is proposed based on the impedance control.A multi-space impedance control strategy is proposed for the multipoint interference situation that may occur during the maintenance operation of a dualarm space robot,and the interference of the external force to the object space is reduced by the decoupling of the force.The final part of this paper is based on a number of simulation experiments on specific on-orbit maintenance tasks.In the impedance control mode,the simulation of the single-arm gripping and moving fault satellites is performed,and compared with the control effect in the position control mode,the advantages and disadvantages of the multiple control modes are proposed.Synchronous impedance model was used to simulate the cutting task.From the results,it can be seen that the two arms can coordinate the stress relationship.The directional impedance control method is used for the task of screwing the screw,which can accomplish the task.Multi-space constant-force loading simulations and rigid object collision simulations are set up for possible interference situations.The multi-space constant-force interference simulation experiment proves the effectiveness of the multi-space impedance control strategy.The collision experiment verifies the robustness of the on-orbit maintenance system under extreme disturbance conditions and can ensure the safety of the dual-arm robot. |
