Dynamic Modeling of Soft Manipulators Actuated by Twisted-and-Coiled Actuators

Soft robots-robots made of soft materials-have strong potential for applications where traditional rigid robots are not suitable (e.g., safely collaborating with humans). However, actuation methods for most existing soft robots still require rigid components to function, and when they do not, they have a limited range of forces and displacements. A new artificial muscle, Twisted-and-Coiled actuators (TCAs), may provide partial solutions to this. They are capable of producing large forces and deformations comparable to or superior to human muscles. However, the dynamic modeling for TCAs when embedded inside soft materials is not trivial due to the coupling of deformations between the actuators and the body. In this paper, we model the dynamics for the thermally driven actuation and extend a dynamic Cosserat rod model to describe the dynamics of the soft body. We also numerically simulate the model to test its correctness. The proposed model is a generalization of existing models and can be applied to the modeling of soft robots when couplings exist between the actuator and the soft body.