| With the exploration and development of space by human beings,the demand for space missions is increasing day by day,and space on-orbit service technology is attracting more and more attention.Space on-orbit capture technology,as the basis of space on-orbit service tasks such as on-orbit fuel filling,space station assembly and space rescue,has also become the current research hotspot.Many countries have begun to conduct in-depth research on the technology of space on-orbit capture.In this paper,based on satellite rescue and assistant orbital transfer tasks in space on-orbit service,a polyhedral net space capture mechanism is proposed,which can be folded and scaled and adapt to a variety of dimensional targets.The mechanism takes 3-RRS parallel manipulator as the main configuration,and combines Bricard mechanism(a spatial single closed-loop six-bar mechanism)as the end-effector with 3-RRS parallel manipulator,which together constitute the principle configuration of the capture mechanism.1)Through the design of deformable mechanism for parallel mechanism platform,a polyhedral net spatial mechanism integrating capture function and operation function is proposed.The whole mechanism is composed of 3-RRS parallel manipulator with 3 degrees of freedom and Bricard closed-loop scaling mechanism(the deformable platform)with 1 degree of freedom.Based on DOF analysis,the mechanism can realize 1 degree of freedom platform scaling,4 degree of freedom overall scaling and 3 degree of freedom operation.2)Through the combination of scaling function and operation function,the polyhedral mesh spatial mechanism can realize the gripper-type capture movement and the net-type capture movement which meet the requirements of on-orbit service capture function.Both modes have carried out strategic planning.When catching long-range targets,the deformable platform moves to the far end by controlling the branch chain of the 3-RRS parallel manipulator,cooperating with the deformable platform as the gripper to realize the gripper-type catching,and when catching short-range targets,the net-type catching is realized by the contraction deformation of the whole mechanism.3)When the mechanism achieves capture,the operation function can be realized through the drive of three branched chains.The locking of the deformable platform after capture makes the whole mechanism equivalent to 3-RRS parallel manipulator.At this time,the movement of two rotations and one movement can be realized to meet the fine-tuning of the angle and distance required for the subsequent operation.In this paper,the degree of freedom,forward kinematics solution,inverse kinematics solution,singularity and workspace of the mechanism are analyzed,and the motion planning of the mechanism for space on-orbit capture is carried out.On the basis of theoretical analysis of the mechanism motion,the virtual prototype model of the mechanism is established by using ADAMS mechanical simulation software to verify the motion of the new mechanism.At the same time,the dynamic characteristics of the mechanism are simulated and analyzed.In addition,according to the working condition and environment of the mechanism,the capture performance of the mechanism was simulated and tested.Based on the data obtained by the simulation in ADAMS software,the prototype of the mechanism was designed,processed and assembled,and the ground platform test was carried out.The ground platform test results show that the designed space capture mechanism has definite motion and can complete folding,posture adjustment and two kinds of capture actions as expected.In this paper,a new mechanism for space on-orbit capture task is proposed.The motion characteristics of the new mechanism are analyzed,and the simulation analysis is carried out with relevant software.Finally,a prototype is developed and tested,which proves the correctness of the conclusion.The work in this paper provides a new idea for the research of space capture mechanism. |
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