Nature’s diversity has inspired scientists and engineers for centuries. The recent technological progress in material design and manufacturing processes has enabled a progressive transfer of nature’s conceptions to robotics and has led to the field of soft robotics. With a paradigm shift from rigid to soft, devices made out of highly deformable materials are developed in such a way that they intrinsically satisfy design criteria such as high flexibility, mechanical robustness, safe human-robot interaction, energy storage or shock absorbability. Soft robots are commonly actuated in two ways: by tendons with variable length routed along or within the body, or by pneumatic actuation which causes the system to deform by changing pressure level. Even though many soft robots have been tested, general modeling and control methods are still not available.
Models proposed for highly deformable bodies require a continuous description of the kinematics which results in systems with infinitely many degrees of freedom. Given that soft robots are composed of deformable bodies, the theory of rigid multi-body dynamics would not be suitable anymore. We will develop and apply nonlinear continuum models with appropriate finite element formulations. The discretization by finite elements describes the dynamics of soft robots eventually as finite degree of freedom systems. To design and control soft robots two inverse problems have to be solved.
(i) The static problem: what are the required control variables for the actuators for a given deformation of the system in space?
(ii) The dynamic problem: how do the actuators’ control variables have to change in time for a given motion of the system?
Eugster, S.R., Deutschmann, B.: "A nonlinear Timoshenko beam formulation for modeling a tendon-driven compliant neck mechanism”, In Proceedings in Applied Mathematics and Mechanics, Vol. 18, e201800208, 2018. PDF
Deutschman, B., Eugster, S.R., Ott, Ch.: "Reduced models for the static simulation of an elastic continuum mechanicsm”, IFAC-PapersOnLine 51(2), pp. 403-408, 2018. PDF
This research forms part of the project “Design, modeling and control of modular tendon-driven elastic continuum mechanisms”, which is conducted in cooperation with the Institute of Robotics and Mechatronics at DLR, Oberfaffenhofen, and is supported by the German Science Foundation (DFG) under project number 405032572. The project is part of the Priority Programm 2100 “Soft Material Robotic Systems”.