  In this study, an inhomogeneous Cosserat rod theory is introduced and
compared to the conventional homogeneous rod for modeling soft manipulators.
The inhomogeneity is addressed by considering the pressure actuation as part of
the rod's constitutive laws, resulting in shifting the neutral axis. This shift
is investigated for a soft manipulator with three parallel fiber-reinforced
actuators. Furthermore, a fiber-reinforced actuator is modeled using nonlinear
continuum mechanics to extract the effect of radial pressure on axial
deformation and is combined with Cosserat model. Finally, several numerical
methods are employed to solve the proposed model and validated by a series of
experiments.
