3.2 Bending Spring
Our method is most similar to the elastic rods model [Bergou et al.
2008; Bergou et al. 2010], which computes the material frame as the
minimizer of elastic energy of the curve. They use these material
frames to compute the bending and twisting energies along the rod.
However, this formulation introduces rotation during simple motion
of a curl, such as a walk cycle, shown in Figure 2 top. This rotation
can be removed by increasing the material’s stiffnesses, but this
change leads to wire-like behavior