The structurally rigid nature of modern robotics often makes them impractical for military usage. Current military robots lack the necessary dynamic flexibility and require complex mechanisms and electrical circuitries to achieve active actuation and complex modes of motion, restricting them from mimicking the locomotion of biological organisms.
To overcome the limitations, researchers from the U.S. Army Research Laboratory and the University of Minnesota developed the first fully 3D printed dielectric elastomer actuator (DEA)— a soft actuator prototype using active materials with tunable parameters such as structural flexibility, morphology and dynamic actuation. The prototype was inspired by invertebrates, and can perform high bending motions that are more practical for military uses.
“In the initial phase of the project, our team began by investigating new methods for emulating the locomotion of invertebrates, which provided fundamental insights into the machineries of their soft distributed actuation circuitries that allow for high bending motions without skeletal support,” professor Michael McAlpine of UMN said in a statement.
The researchers identified the parameters that can be manipulated to accomplish novel functions like highly flexible modes of motion by focusing on the innate mechanisms of the distributive actuation observed in nature.
The team first built and tested a prototype similar to the actuators found in nature through a custom-built 3D printing platform. They then developed a unified mathematical model to study the sensitivity of each parameter and predict the various optimal actuation mechanisms.
The 3D printed distributed actuation circuitries involve soft, stretchable materials that feature mechanical properties similar to biological organisms like cephalopods and worms.
“Unlike current 3D printed DEAs, the new fabrication method does not require post-processing steps, such as assembly, drying or annealing,” lead author Ghazaleh Haghiashtiani, said in a statement. “With the new 3D printing method, the solider can take advantage of the unique actuation properties of soft DEAs at the fundamental materials level with microscale resolution and complexity, with minimal prior expertise.”
The researchers developed a generalized model that uses an energetic formulation approach to help identify the tuning physical properties by exploiting the interplay between the materials and dynamic nonlinearities to argument the motion. The model also highlights the electromechanical coupling between the electrical field and nonlinear structural stiffness through the distributive actuation circuitries.
The researchers now plan to develop the experimental and theoretical principles governing the interplay between the internal interfaces and kinetics of interactions in time-variant systems observed in biological organisms to ensure their flexible locomotion and resilience.
“The intriguing interactions among the materials’ micromechanical properties and various nonlinearities may provide new scientific opportunities to emulate the symbiotic interactions in biological systems,” Ed Habtour, PhD, an ARL researcher who specializes in nonlinear structural dynamics, said in a statement.
“If we can understand these interactions, then we can use those insights to fabricate dynamic structures and flexible robots which are designed to be self-aware, self-sensing and capable of adjusting their morphologies and properties in real time to adapt to a myriad of external and internal conditions.”