# Design of a Bionic Spider Robot with a Two-Degrees-of-Freedom Leg Structure and Body Frame
## 1 Introduction  
The inspiration for the biomimetic robots was originally derived from biology, and it was an imitation of biological form and movement [1]. In recent years, biomimetic robots have found extensive applications in the military, industry, and health and environmental protection industries due to the continuous advancement of technology. For example, bionic robots are used for complex environment detection [2; 3; 4], disaster relief [5; 6] and pipeline detection [7; 8; 9]. At present, biomimetic robots have become a research area of concern, mainly focusing on the study of biomimetic structures, materials and control systems. The study of biomimetic structures requires detailed research and analysis on the physiological structure, function and behavior of organisms, with the purpose of integrating the advantages of organisms into mechanical design, such as unmanned aerial vehicles designed using the flight principle of insects [10] and underwater vehicles designed to imitate fish swimming [11]. At the same time, biomimetic materials research focuses on the innovative creation and application of materials, such as bionic skin [12; 13], bionic bone [14], and bionic muscle [15; 16]. Biomimetic control technology is also a prominent research field, mainly aiming at research on the biological nervous system [17; 18] and the research of control methods oriented towards the biological nervous system [19]. Among many bionic objects, spiders are favored by many researchers and have become popular bionic objects because of their unique biological characteristics and outstanding athletic ability. For example, in terms of mechanical structure and control, [PERSON] and [PERSON] [20] achieved modeling and control of a quadruped spider robot through simulation and proportional prototyping; [PERSON] et al. [21] proposed a mathematical model for spider robots aimed at group control synthesis, emphasizing the potential for multi robot collaboration and practical applications; [PERSON] et al. [22] studied the omnidirectionaljumping ability of legged robots based on the behavioral mechanism of jumping spiders; [PERSON] et al. [23] designed and conducted simulation analysis of a hexapod biomimetic spider robot, emphasizing its advantages in flexibility and stability; [PERSON] et al. [24] proposed a biomimetic design and technological innovation method by studying the hydraulic joints in spider legs and combining biomimetics, computational fluid dynamics (CFD) simulation, and design; [PERSON] et al. [25] explored the design and analysis of control systems for spider-like robots, with a focus on their application in maintenance engineering. Finally, [PERSON] et al. [26] developed a spider joint-shaped biomimetic actuator with an approximate triangular prism shape, demonstrating new potential in robot motion and load-bearing capacity. In existing research, the leg motion structures of biomimetic spider robots are often designed to incorporate multiple degrees of freedom (DOFs), which simulate the movement capabilities of spiders. Although this can simulate the movement ability of spiders well, it also brings many challenges. First of all, each degree of freedom requires an independent control, and multiple degrees of freedom result in greatly increased complexity of the control, and it is difficult to achieve autonomous operation due to the complexity of the environment [27]. Secondly, the need for additional actuators to drive multi-degree-of-freedom structures can lead to increased energy consumption, especially in environments with limited energy resources [28]. Thirdly, the additional weight and volume required to adapt to multi-degree-of-freedom configurations increase the complexity of manufacturing and maintenance, thereby limiting the applicability of the robot environment. In addition, the increase in the number of components in multi-degree-of-freedom structures increases the likelihood of component failures, which may impair the performance of robots and even lead to system failures.