## 2 Design of the Lunar Exploration Hexapod Robot  
### Overall Scheme Design  
The Moon is in a low-temperature, hypoxia, low-pressure, low-gravity environment, and lunar soil has high adsorption that makes it easy to corrode materials, so it has the requirements of light weight, high performance and corrosion resistance for the lunar exploration robot. Therefore, the robot body material needs to have excellent comprehensive properties such as low density, high specific stiffness, low expansion and high thermal conductivity. Traditional lightweight structural materials such as aluminum alloys and titanium alloys are difficult to fully meet the above requirements, while SiCP/Al composites have excellent comprehensive properties such as low density, high specific stiffness, low expansion and corrosion resistance, which are widely used in the aerospace field [21; 22; 23]. Comprehensively speaking, the robot in this paper is selected as a whole SiCP/Al composite material, and its performance parameters are shown in Table 1.  
As shown in Figure 1, the overall dimensions of the lunar exploration hexapod robot's design are 301 mm \(\times\) 324 mm \(\times\) 132 mm, with a mass of 10 kg. The structural design prototype of the lunar exploration hexapod robot is a hexapod insect in nature. The leg layout adopts an elliptical layout, which reduces the overall volume of the robot compared with the circular layout. Compared with the rectangular layout, the elliptical layout ensures that the robot legs will not collide while having a large swing space. As shown in Figure 2, the fan represents the range of movement that each leg can move, and L represents the maximum distance that a single leg can walk.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Properties** & **SiCP/Al** \\ \hline Density/(g/cm\({}^{3}\)) & 2.94 \\ Modulus of elasticity/Gpa & 213 \\ Specific modulus/10\({}^{5}\) m & 72.4 \\ Thermal conductivity/(W\(\cdot\)m\({}^{-1}\cdot\)K\({}^{-1}\)) & 195.6 \\ Thermal expansion coefficient/106K\({}^{-1}\) & 8.0 \\ Tensile strength/Mpa & 363.4 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Various performance parameters of SiCP/Al composites.  
Figure 1: Overall structure of the lunar exploration hexapod robot.  
Figure 2: Schematic diagram of the fuselage layout.  
To reduce the overall weight of the robot while ensuring good load capacity, the leg structure of the robot is designed to mimic the joints of insect legs, including the coxa, femur and tibia. Adjacent segments are connected by adjacent joints to enable rotation, as illustrated in Figure 3. The robot's drive system employs an STM32F407 control board and a 24-channel servo driver board, utilizing serial communication. The control of the 18 drive motors of the robot is achieved by outputting PWM signals. The motors used in this study are RDS3115 dual-axis digital servos, as depicted in Figure 4. The servos internally incorporate a microcontroller (MCU) for control, adjusting the angle through PWM pulse-width modulation with a rotation range of 0-180\({}^{\circ}\). They exhibit the advantages of high control precision and good linearity, with specific parameters detailed in Table 2.