Dynamic Simulation of Dielectric Elastomer Actuated Multibody Systems

A three-dimensional electro-mechanically coupled finite element model for dielectric elastomers is used to actuate multibody systems. This setting allows exploring the complex behavior of humanoid robots that are driven by artificial muscles instead of electrical drives. The coupling between the finite element muscle model and the rigid bodies is formulated at configuration level, where Lagrange multipliers account for constraint forces, leading to differential algebraic equations of index-3. A well-chosen set of redundant configuration variables for the multibody system avoids any rotational degrees of freedom and leads to linear coupling constraints. As a result, the coupling between the artificial muscles and the multibody system can be formulated in a very modular way that allows for easy future extension. The applied structure preserving time integration scheme provides excellent long time energy behavior. In addition, the index-3 system is solved directly with numerical accuracy, avoiding index reduction approximations.