  Soft robots have high adaptability and safeness which are derived from their
softness, and therefore it is paid attention to use them in human society.
However, the controllability of soft robots is not enough to perform dexterous
behaviors when considering soft robots as alternative laborers for humans. The
model-based control is effective to achieve dexterous behaviors. When
considering building a model which is suitable for control, there are problems
based on their special properties such as the creep behavior or the variability
of motion. In this paper, the lumped parameterized model with viscoelastic
joints for a soft finger is established for the creep behavior. Parameters are
expressed as distributions, which makes it possible to take into account the
variability of motion. Furthermore, stochastic analyses are performed based on
the parameters' distribution. They show high adaptivity compared with
experimental results and also enable the investigation of the effects of
parameters for robots' variability.
