  Recently soft robotics has rapidly become a novel and promising area of
research with many designs and applications due to their flexible and compliant
structure. However, it is more difficult to derive the nonlinear dynamic model
of such soft robots. The differential kinematics and dynamics of the soft
manipulator can be formulated as a set of highly nonlinear partial differential
equations (PDEs) via the classic Cosserat rod theory. In this work, we propose
a discrete modeling technique named piecewise linear strain (PLS) to solve the
PDEs of Cosserat-based models, based on which the associated analytic models
are deduced. To validate the accuracy of the proposed Cosserat model, the
static model of the conical cantilever rod under gravity as a simple example is
simulated by using different discretization methods. Results indicate that PLS
Cosserat model is comparable to the mechanical deformation behavior of
real-world soft manipulator. Finally, a parameters identification scheme for
this model is established, and the simulation as well as experimental
validation demonstrate that using this method can identify the model physical
parameters with high accuracy.
