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Data and simulation model files for: Variable-stiffness morphing wheel inspired by the surface tension of a liquid drop

Data files

Jul 23, 2024 version files 38.66 MB

Abstract

Wheels have been commonly used for locomotion in mobile robots and transportation systems due to their simple structure and energy efficiency. However, the performance of wheels in overcoming obstacles is limited compared to their advantages in driving on normal flat ground. Here, we present a variable stiffness wheel inspired by the surface tension of a liquid drop. In a liquid drop, as the cohesive force of the outermost liquid molecules increases, the net force pulling the liquid molecules inward also increases. This leads to high surface tension, resulting in the liquid droplet reverting to a circular shape from its distorted shape induced by gravitational forces. Similarly, the shape and stiffness of the wheel can be controlled by changing the traction force at the outermost smart chain block. As the tension of the wire spokes connected to each chain block increases, the wheel characteristics reflect those of a general circular-rigid wheel, which has an advantage in high-speed locomotion on normal flat ground. Conversely, the modulus of the wheel decreases as the tension of the wire spoke decreases, and the wheel can be easily deformed according to the shape of obstacles. This makes the wheel suitable for overcoming obstacles without requiring complex control or sensing. Based on this mechanism, the wheel is applied to a 2-wheeled wheelchair system weighing 120 kg, and the state transition between a circular high-modulus state and a deformable low-modulus state is realized in real-time when the wheelchair drives in an outdoor environment.