# Design, Analysis, and Experiment of a Wheel-Legged Mobile Robot
## 6 Conclusions  
As hybrid mobile robots have the advantages of various mobile structures after combining their characteristics, they attract wide attention from many scholars. A hybrid wheel-legged mobile robot that combines the structural characteristics of wheeled and legged structures is proposed within the scope of hybrid mobile robots. The contents are as follows:  
* After statics modeling and analysis, it is determined that the number of spokes of the robot's wheel-legs is three. Based on the specific step parameters, a geometric analysis is used to determine the chord length of the spokes in the robot's wheel-leg. The design of the parameters of the wheel-legged structure ensures the satisfactory obstacle-crossing capability of the robot.
* To further expand the application scenarios of the robot, the curling mechanism is selected as the main robot body. Particle swarm optimization is used to determine the number of robot sections \(n=5\) and the length of each section \(l=16\) mm. Based on this result, a prototype robot is made taking into account the strength of the components, the lightweight of the robot body, etc., and the materials for each key part are also determined.
* To improve the working conditions of the drive motor and the curling motor, the material of the wheel-leg in contact with the ground, namely, the wheel-leg cover material is selected after dynamic analysis. After considering the climbing ability and values of torque, etc., rubber is used for the wheel-leg cover.
* After prototype production and wheel-leg cover material selection, experiments are carried out on different terrains, including relatively complex terrains such as grassland, gritty land, and slopes. The robot demonstrates good performance.  
In conclusion, the proposed wheel-legged mobile robot is adaptable to multiple terrains with strong obstacle-crossing capability, which makes up for the drawbacks of traditional mobile robots in these aspects. To further improve the performance of the robot, future research can be carried out on control strategies and intelligence in the future. This will help give full play to wheel-legged mobile robots' advantages, enabling them to assist humans when completing tasks in scientific exploration and rescue.  
Conceptualization, J.L. and Y.L.; methodology, Z.Z.; software, Z.Y.; validation, Z.Z.; formal analysis, Y.L.; investigation, Z.Z.; resources, J.L.; data curation, Y.G.; writing--original draft preparation, Y.Z. and Z.Y.; writing--review and editing, J.L. and Y.L.; supervision, T.S.; project administration, J.L.; funding acquisition, T.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Natural Science Foundation of China (Project No. 51535008, 51721003) and the Programme of International Collaboration (\"1111 Program\") under Grant No. B16034.  
Not applicable.  
The data presented in this study are available in this article.  
The authors are grateful to the Mechanisms and Robotic System Laboratory of Tianjin University and the Centre for Advanced Mechanisms and Robotics of Tianjin University for providing research opportunities and financial support.  
The authors declare no conflict of interest.