Optimal Control of Dielectric Elastomer Actuated Multibody Dynamical Systems.

Area of Science:

• Robotics
• Mechanical Engineering
• Materials Science

Background:

• Dielectric elastomer actuators (DEAs) are crucial artificial muscles in soft robotics.
• Modeling DEA behavior in flexible multibody dynamics is complex.
• Optimal control strategies are needed for precise DEA actuation.

Purpose of the Study:

• To present a simulation model for optimal control of DEA-actuated flexible multibody dynamics systems.
• To model the DEA as an electromechanically coupled geometrically exact beam.
• To integrate contact interactions and boundary conditions into the control framework.

Main Methods:

• Developed a reduced free energy function for the electromechanically coupled beam.
• Formulated an optimal control problem minimizing an objective function subject to dynamic balance equations and complementarity conditions.
• Employed a direct transcription method, semidiscretization with 1D finite elements, and temporal discretization with a variational integrator.
• Reduced discrete Euler-Lagrange equations using null space projection and solved the constrained nonlinear optimization problem with an Interior Point Optimizer.

Main Results:

• Successfully modeled DEA-beam as a flexible artificial muscle within multibody systems.
• Incorporated contact interactions via unilateral constraints for grasping simulations.
• Demonstrated model effectiveness through numerical examples: cantilever beam, soft robotic worm, and soft robotic grasper.

Conclusions:

• The developed simulation model provides a robust framework for optimal control of DEA-actuated flexible multibody systems.
• The model accurately represents electromechanical coupling, contact, and boundary conditions.
• This work advances the design and control of soft robotic systems.