3D-printed robotic hand can play Super Mario

Engineers from the University of Maryland (UMD) have 3D printed a soft robotic hand that is agile enough to play — and beat — Nintendo’s Super Mario Bros. Their feat, described in the journal Science Advances, demonstrates a promising innovation in the field of soft robotics, which centres on creating flexible, inflatable robots that are powered using water or air rather than electricity.

Soft robots’ inherent safety and adaptability has sparked interest in their use for applications like prosthetics and biomedical devices. Unfortunately, controlling the fluids that make these soft robots bend and move has been especially difficult — until the UMD team had the breakthrough of 3D printing fully assembled soft robots with integrated fluidic circuits in a single step.

“Previously, each finger of a soft robotic hand would typically need its own control line, which can limit portability and usefulness,” said co-first author Joshua Hubbard. “But by 3D printing the soft robotic hand with our integrated ‘fluidic transistors’, it can play Nintendo based on just one pressure input.”

As a demonstration, the team designed an integrated fluidic circuit that allowed the hand to operate in response to the strength of a single control pressure. For example, applying a low pressure caused only the first finger to press the Nintendo controller to make Mario walk, while a high pressure led to Mario jumping. Guided by a set program that autonomously switched between off, low, medium and high pressures, the robotic hand was able to press the buttons on the controller to successfully complete the first level of Super Mario Bros. in less than 90 seconds. Because the game’s timing and level make-up are established, and just a single mistake can lead to an immediate game over, this provided a means for evaluating soft robot performance that is challenging in a manner not typically tackled in the field.

“Recently, several groups have tried to harness fluidic circuits to enhance the autonomy of soft robots, but the methods for building and integrating those fluidic circuits with the robots can take days to weeks, with a high degree of manual labour and technical skill,” said co-first author Dr Ruben Acevedo. “To overcome these barriers, the team turned to PolyJet 3D printing, which is like using a colour printer but with many layers of multi-material ‘inks’ stacked on top of one another in 3D.”

“Within the span of one day and with minor labour, researchers can now go from pressing ‘start’ on a 3D printer to having complete soft robots — including all of the soft actuators, fluidic circuit elements and body features — ready to use,” added study co-author Kristen Edwards.

The team’s paper has been made open access for anyone to read, with a link in the supplementary materials to all of the electronic design files from their work — meaning anyone can readily download, modify and 3D print all of the soft robots and fluidic circuit elements. As explained by team leader Ryan D Sochol, “It is our hope that this open-source 3D printing strategy will broaden accessibility, dissemination, reproducibility and adoption of soft robots with integrated fluidic circuits and, in turn, accelerate advancement in the field.”

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