# Design and Dynamic Simulation Verification of an On-Orbit Operation-Based Modular Space Robot
## 1 Introduction  
Space robots have been playing an irreplaceable role in the field of on-orbit operations, and almost all major countries in the world have conducted in-depth research on this field. As is known to all, an on-orbit operation-based modular space robot is a special hypersonic vehicle which can complete space missions around the Earth's orbit. However, the structure of space robots using a traditional configuration scheme cannot be changed, since they contain specific functions. Recent years have witnessed the rapid development of modular reconfigurable robots, which are more adaptable to missions and environments, as they can determine the number of modules and change configurations according to different missions. Thus, they have much more ideal application prospects in the field of on-orbit operations. In general, modular reconfigurable robots are divided into two types: reconfigurable robots (RMRS) [1] and self-reconfigurable robots (SRMRS) [2], according to whether they can complete reconstruction autonomously. In this case, self-reconfigurable robots are divided into four types according to different unit modules: chain type, mobile type, crystal type, and hybrid type [3]. The chain robot system forms a chain structure by connecting unit modules in series, such as PolyBot [4], CONRO [5], YaMoR [6], etc. Mobile modular robot modules can achieve aggregation and discreteness, such as the SWARM-bot of the Ecole Polytechnique Federale de Lausanne in Switzerland [7] and the SamBot developed by Beijing University of Aeronautics and Astronautics [8]. Crystal format robots are named due to the fact that their unit modules are in a crystal format, such as Molecules developed by [PERSON] et al. [9, 10] and Auke developed Roombots [11, 12]. Furthermore, Murata developed M-TRAN [13], and [PERSON] developed Superbot [14], which realized autonomous connection and reconstruction of modules, i.e., they were hybrid robots. In terms of reconfigurable robot research, typical representatives include the RMMS developed by Carnegie MellonUniversity [15], the dexterous robotic arm developed by Harbin Institute of Technology and MRRS American Robotics Research Corporation [16; 17; 18], DLR's LWR-III [19], the RMMS of Carnegie Mellon University [20], and Harbin Institute of Technology's Modular Reconfigurable Robot System (MRRES) [21], etc. [PERSON] [22] described the Soldercube module using lattice configuration, explored the non-lattice applications of the system, and discussed the effects of utilizing volume manufacturing processes in module production. [PERSON] et al. [23] developed a sliding Triangular Lattice Modular Robot (STRIMOR) and used a rapidly exploring random tree (RRT*) algorithm to solve the self-reconfiguration (SR) problem. [PERSON] et al. [24] proposed a Complete Tileset Energy-Aware Coverage Path Planning (CTPP) framework for a tiling self-reconfigurable robot named hRombo with four rhombus-shaped modules, which can enable robots to navigate from source to target in different workspaces with the least consumed energy and time. [PERSON] et al. [25] investigated a self-reconfiguring robot named Ant3 DBot consisting of four semicircular iron spheroid shells, telescopic legs, and internal magnets that can rotate around the center, so as to verify the basic ability of a single module to overcome obstacles as well as the cooperative motion of multiple robots. [PERSON] et al. [26] presented a novel concept for a modular robot that has the abilities of compliant actuation and self-reconfiguration to form compliant structures named Module-W (M-W). Stimulated by the previous discussion, this paper investigates the design and dynamic simulation verification of a modular space robot based on on-orbit operation.