# Design and Stiffness Optimization of Bionic Docking Mechanism for Space Target Acquisition
## 1 Introduction  
As the key equipment for space target acquisition, space docking and transposition is the core technology that all aerospace powers strive to develop [1; 2; 3; 4; 5]. At present, space docking transposition is required not only to solve the acquisition of spacecraft, but also to buffer collision energy, avoid serious collisions and reduce the impact of docking. The realization of soft docking in space on orbit acquisition is of great significance to complete the space on orbit acquisition task. In recent years, the design of new space docking mechanisms to realize soft docking is still a research hotspot of many scholars [PERSON] et al. [6] developed a new type of end effector prototype by combining the tendon-sheath transmission system with a steel cable snaring mechanism. [PERSON] et al. [7] designed and studied a variable topology 3-RSR polyhedron docking mechanism, and verified the practicability of the structure; [PERSON] et al. [8] designed a light and small three arm noncooperative target satellite docking mechanism. [PERSON] [9], et al. developed a flux pinned docking mechanism (FPDM), and designed and established the experimental demonstration system. [PERSON] et al. [10] proposed an integrated active genderless docking mechanism which allows for efficientdocking while tolerating misalignments. [PERSON] et al. [11] established a novel model of space electromagnetic docking to solve the problem of traditional plume contamination and short service life. [PERSON] et al. [12] presented one novel docking mechanism with a T-type locking structure and proved the rationality of the proposed mechanism. [PERSON] et al. [13] studied the movement space of the LIDM's capture system and proposed the main factors affecting the movement space. [PERSON] et al. [14] studied the innovational design technique of a docking cone and developed a new satisfactory docking cone. [PERSON] et al. [15] studied the application of two-bar slider rocker mechanisms in three-state rigid active docking, and verified its effectiveness through experiments. [PERSON] et al. [16] proposed a high temperature superconducting magnetic docking mechanism which consisted of a high temperature superconductor (HTS) bulk installed on a target spacecraft module and an electromagnet installed on a tracking spacecraft module based on the flux pinning effect of an HTS. Meanwhile, by discussing the influence of docking mechanism parameters on the soft docking of the micro satellite, many scholars proposed new docking strategies based on the existing docking mechanisms, and verified their effectiveness through simulation experiments. [PERSON] et al. [17] verified the feasibility of realizing the action of the butt ring with the multi-motor combined control based on the scaled docking mechanism prototype of an aluminum alloy. [PERSON] et al. [18] proposed a prediction model for the transmission error of CDS based on their cable deformation to improve the assembly efficiency of docking locks. [PERSON] et al. [19] established the model of grasping docking mechanism by using the mathematical methods, and analyzed the contact and collision problems in the process of grasping. [PERSON] et al. [20] proposed a new docking mechanism that provides the basis for the connection and separation of small spacecraft in space. [PERSON] et al. [21] proposed a feasible docking mechanism based on the non-cooperative target docking technology points, and verified its effectiveness. Taking successful docking as the evaluation standard, [PERSON] et al. [22] discussed the influence of docking mechanism parameters on micro/small satellite soft docking. [PERSON] et al. [23] investigated the problems of spacecraft self- and soft-docking via coupled actuation of magnetic fields. The aforementioned research on the space docking mechanism mainly focuses on the development of the capture mechanism end-effect device, as well as the contact mode and contact strategy research, but the manipulator was not employed as part of the docking mechanism.