Screw-Based Modeling of Soft Manipulators With Tendon and Fluidic Actuation

A screw-based formulation of the kinematics, differential kinematics, and statics of soft manipulators is presented, which introduces the soft robotics counterpart to the fundamental geometric theory of robotics developed since Brockett's original work on the subject. As far as the actuation is concerned, the embedded tendon and fluidic actuation are modeled within the same screw-based framework, and the screw-system to which they belong is shown. Furthermore, the active and passive motion subspaces are clearly differentiated, and guidelines for the manipulable and force-closure conditions are developed. Finally, the model is validated through experiments using the soft manipulator for minimally invasive surgery STIFF-FLOP.