A new method for making a robotic tentacle with more agility and degrees of freedom (DOF) of movement relies on 3D printing. Developed by Cornell University engineers, the method aims at producing a soft robotic actuator by recreating the design of an octopus tentacle's muscle arrangements and using a commercially available elastomeric that can be 3D printed with a stereolithography (SLA) system.
The team set out to find alternative methods for creating elastomeric soft robotic actuators. Although advances in materials, fabrication techniques, and simulation tools have made elastomeric soft robotic systems possible, creating actuators for them has been a different story. In the short video below, you can see different versions of these new tentacles strut their stuff, with varying degrees of flexibility and DOF of movement.
Soft robot systems continuously deform their shape. Deformable materials like fluids, gels, and elastomers mimic the properties of biological organisms to help them achieve this, but a corresponding architecture needs to be sufficiently complex and capable of multiple configurations. In particular, creating soft actuators can be challenging, since they must be capable of high degrees of freedom to mimic complex biological movements.
Previously, elastomeric soft robotic actuators couldn't be produced via 3D printing methods with the agility and degrees of freedom provided by the new method, said senior author of the study Rob Shepherd, assistant professor of mechanical and aerospace engineering, in a press release.
The team's research is available in an article published in the journal Bioinspiration & Biomimetics, which you can download. In that article, they describe the detailed mechanical design of a digital mask projection SLA system for 3D printing soft actuators.
Using rheological and tensile testing, they identified and characterized a commercially available photopolymerizable elastomer in both liquid and solid forms. One outcome was the ~40% strain-to-failure of structures printed with this system. Using the resulting material properties, the team conducted and analyzed numerical simulations of pleated actuator architectures, to increase actuation amplitudes and reduce stress concentration. They then fabricated and tested several antagonistic pairs of actuators for tentacle-like, 4-DOF motion.
Funding was provided by the Air Force Office of Scientific Research, 3M, and the National Science Foundation.
Ann R. Thryft is senior technical editor, materials & assembly, for Design News. She's been writing about manufacturing- and electronics-related technologies for 27 years, covering manufacturing materials & processes, alternative energy, and robotics. In the past, she's also written about machine vision and all kinds of communications.
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