Cosserat Modeling of Trimmed Helicoid Soft Arms with a Separated-Section Constitutive Law

This paper addresses a limitation in traditional Cosserat rod models for soft robots, where sectional stiffness is typically constructed by summing material properties over a common cross-section. The proposed separated-section constitutive law is specifically designed for trimmed helicoid arms, where load-bearing helix domains are separated and connected only through sparse fused crossings. The method evaluates each helix domain's constitutive response in its local reference frame before mapping back to the global coordinate system, providing more accurate mechanical modeling for soft robotic structures with complex cross-sectional geometries.