# Design and Simulation of On-Orbit Assembly System Based on Insect-Inspired Transportation
## 2 Scheme Design of Robot System  
As shown in Figure 1, this paper presents a conceptual diagram of the in-orbit assembly of space structure assembly units. The hexagonal units, which are widely used in space structures, are selected as the assembly objects, and the robot structure with moving, handling, and assembly functions is used to connect the assembly units. Due to the special microgravity environment in space, the robot can make small adjustments and movements around the assembly unit. This new robot in-orbit assembly system can complete assembly tasks under autonomous control, enabling efficient, accurate assembly, connection, and transportation tasks, and is adaptable to different types of assembly units, with high flexibility and scalability. The use of robots for in-orbit assembly can improve the efficiency and accuracy of assembly tasks compared to manual or traditional machine assembly methods. As shown in Figure 1, the three-stage workflow of in-orbit assembly robots is presented. During this process, the assembly robot assists in handling fixed connections and performs assembly work when the main robotic arm of the space station moves various assembly units to close proximity. The assembly robot can effortlessly handle large assembly units due to the unique weightless environment in space. The planning of robot assembly work is divided into three phases. Phase One: The robot crawls along the edge of the unit truss to perform a cruising motion. At this time, the in-orbit assembly robot performs an unloaded cruising motion and moves laterally along the truss edge. Phase Two: The robot grasps the assembled unit and performs cruising motion on the edge truss of another unit. At this time, the in-orbit assembly robot performs a loaded cruising motion, and the deformed swing of the grasped unit module due to its flexibility will affect the robot's motion process. Thus, motion analysis is conducted, taking into account the effect of flexible units. Phase Three: The robot moves to the preset pose to complete the assembly of the truss unit. At this time, on the basis of Stage Two, the in-orbit assembly robot holds one assembly unit per leg and uses the last leg to play the role of the manipulator to complete the in-orbit assembly of the assembly unit through posture adjustment. In this paper, we propose a novel robot on-orbit assembly system for space structures to meet the task requirements of on-orbit assembly. The robot is composed of a body and three composite mechanical arm-legs, which can dock and transfer assembly units with the transport spacecraft unit. It can also crawl along the edge truss of the assembly unit to the specified position while ensuring accuracy for completing the on-orbit assembly. Figure 1: Schematic diagram of the conceptual on-orbit assembly scheme for space structure assembly units. The design of the robot is inspired by the ants in nature that carry heavy loads, as shown in Figure 2a. From a force perspective, when an ant stands upright, its body can support the weight of the load because its leg muscles can provide enough support. In addition, ants demonstrate flexible path-planning abilities during transportation. In space environments, path planning can be achieved through algorithms and intelligent control to avoid obstacles, maximize the use of space resources, and ensure efficient and safe transportation paths. Moreover, space environments present a variety of complex structures and special working spaces. By borrowing from the adaptive capabilities of ants, robots or mechanical devices can be designed with similar abilities to overcome challenges in space. In addition, ant transportation behavior also demonstrates efficient energy use and economy. Energy supply is a crucial issue in space environments, so in designing space transportation systems, optimizing energy use, reducing energy consumption, and extending system runtime can be taken into account.