  Soft robots are interesting examples of hyper-redundancy in robotics,
however, the nonlinear continuous dynamics of these robots and the use of
hyper-elastic and visco-elastic materials makes modeling of these robots more
complicated. This study presents a geometric Inverse Kinematic (IK) model for
trajectory tracking of multi-segment extensible soft robots, where, each
segment of the soft actuator is geometrically approximated with multiple rigid
links connected with rotary and prismatic joints. Using optimization methods,
the desired configuration variables of the soft actuator for the desired
end-effector positions are obtained. Also, the redundancy of the robot is
applied for second task applications, such as tip angle control. The model's
performance is investigated through simulations, numerical benchmarks, and
experimental validations and results show lower computational costs and higher
accuracy compared to most existing methods. The method is easy to apply to
multi segment soft robots, both in 2D and 3D. As a case study, a fully
3D-printed soft robot manipulator is tested using a control unit and the model
predictions show good agreement with the experimental results.
