2-DOF Transformable Wheel Preserving Circular Projection During Radius Variation

초록

This paper presents a transformable wheel achieving continuous radius variation while preserving a circular projected profile to eliminate rolling vibrations common in existing variable-radius designs. By formulating the panel geometry as intersecting cylindrical surfaces, a systematic baseline for continuous circularity is analytically established throughout transformation. A synthesized two-degrees-of-freedom linkage mechanism embeds the required cosine-based radius-rotation relationship into the structure, enabling continuous radius adjustment and differential panel deployment. Kinematic and experimental validations confirm projected circularity preservation and demonstrate enhanced obstacle negotiation. Specifically, the proposed wheel successfully overcame a normalized step height of $H/r_{\text{eff}}=0.52$ (50 mm step), whereas an identical rigid baseline wheel failed to climb the same obstacle ($H/R=0.50$) due to continuous edge slippage. This geometric-kinematic integration provides a unified architecture supporting both smooth nominal rolling and adaptive reconfiguration within a single mechanism framework.

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