TWLHex: A Biologically Inspired Multi-Morphology Transformable Wheel-Legged Hexapod

This letter presents a novel biologically inspired transformable wheel-legged hexapod, TWLHex, which is capable of actively switching among three morphologies: leg, wheel, and spoke. The mechanical design and kinematic models for transformable mechanism (TranMech) and wheel-spoke leg mechanism (WSLegMech) are introduced. Based on the established kinematic models, multiple experiments effectively validate the robot's capabilities in all three morphologies, demonstrating that the robot can adapt to various terrains in the leg-morphology, overcome step obstacles in the spoke-morphology, and roll forward in the wheel-morphology. The locomotion performance of leg and wheel morphology is evaluated. Additionally, TWLHex can even climb 45° stair in the leg-morphology and the motion planning of stair-climbing under leg-morphology is discussed in detail.