Flexibility and Granular Terrain Adaptability of a Linkage-Based Wheel-Legged Robot: LinkWheg

Wheel-legged robot has been widely used in challenging terrain exploration due to their stability, simplicity, and flexibility. However, the legs of the wheel-legged series robot has significant weight, and its application in granular terrain is relatively limited. In this article, a linkage-based wheel-legged series robot (LinkWheg) is designed, which combines the flexibility and adaptability of a legged robot with the high efficiency of a wheeled robot. The legs adopt a four-bar design to ensure their motion range while reducing the weight (at least 40.9%) and increasing the load capacity (nearly 100% of the robot weight). The motion speed and pulling force of three different gaits in sand slopes are studied by theoretical analysis and validated by experiments. It can be proven that the developed LinkWheg robot can adapt well to motion multiterrain such as crossing obstacle, fluctuating changes, omnidirectional motion, and maintaining balance, while maintaining its stable posture.