| Compared with the traditional passive buffered docking,the low impact space docking method has the advantages such as the decreased contact force and the increased allowable initial position-orientation errors between the two space vehicles,so it becomes a hot research focus of the international space technology.The contact force signal is measured and processed real-timely,and then the position command is adjusted,so the control system is more complex.Besides,the initial docking condition is more severe,so it is necessary to ch oose an appropriate optimization objective to carry out the optimal design of the low impact space docking mechanism.Thus,this paper carries out a research on the optimal design method and the active compliant control strategy for the low impact space do cking,reserving theoretical basis for our country to launch low impact space docking.Firstly,in order to complete the low impact docking simulated experiment,the Stewart platform is employed as the active docking mechanism,and the kinematics,Jacobian matrix is analyzed in this paper,laying basis for the subsequent docking experiment and dimension synthesis.Secondly,for the purpose of improving the performance of the docking mechanism,the evaluation indexes for parallel manipulator are analyzed ov erall in this paper.And the transmissibility index which is frame-independent and unit homogeneous is employed to conduct the optimization mission.Besides,the global transmission index(GTIc)is proposed to evaluate the performance of the parallel manipulator whose workspace is determinate.On the basis of the index,the dimensional synthesis of the docking mechanism is completed using the particle swarm algorithm,laying the theoretical basis for the design of the docking mechanism.Thirdly,in order to achieve the low impact space docking and decrease the contact force in the docking process,this paper designs an inertia-damping controller on the basis of the traditional impedance control,and then the restoring force caused by the end-effector’s being away from the desired position is eliminated,making the manipulator show a complete adaptation to the environment.Besides,the desired force resolving method is proposed to judge if the docking process has completed.The joint space compliant control strategy and the Cartesian space compliant control strategy are proposed to control the docking process,and the co-simulation with MATLAB and ADAMS is carried out to verify the availability and to compare the merits and demerits of these control strategy.Finally,the parallel manipulator is designed as the passive docking mechanism,thus finishing the docking simulated experiment system.Besides,this paper analyzes the inverse kinematics of the passive docking mechanism,so the docking experiments under different initial docking conditions can be completed.The electrical control system and software control system are completed and the experiments are carried out to verify the control strategy.And the experiments flow for space docking and the related technology such as the force signal filter,the gravity compensation,and the position-orientation errors measurement are completed for the docking experiments.And then the low impact space docking experiment is conducted to verify the availability of the con trol strategy. |
