Researchers Advance Next Generation Soft Robotics

Researchers at Harvard John A. Paulson School of Engineering and Applied Science (SEAS) have developed electrically-driven soft valves that can control hydraulic soft actuators. According to the team, these valves could be applied in assistive and therapeutic devices, soft grippers, bio-inspired soft robots, surgical robots, and much more.

Challenge of Building Soft Robots

Researchers still struggle to build entirely soft robots because they require many components to power the devices, and these devices are rigid. Soft robots driven by pressurized fluids open up new opportunities to interact with delicate objects, which traditional rigid robots cannot do. This is why the new development is so crucial.

The research was published in the Proceedings of the National Academy of Sciences (PNAS). It was supported by the National Science Foundation and the National Robotic Initiative.

Robert J. Wood is a Harry Lewis and Marlyn McGrath Professor of Engineering and Applied Sciences at SEAS and senior author of the research. 

“Today’s rigid regulation systems considerably limit the adaptability and mobility of fluid-driven soft robots,” said Wood. “Here, we have developed soft and lightweight valves to control soft hydraulic actuators that open up possibilities for soft on-board controls for future fluidic soft robots.”

Soft Valves

While soft valves have been around for a while, none have yet to achieve the required pressure or flow rates for existing hydraulic actuators. To get around this, the team developed new electrically powered dynamic dielectric elastomer actuators, or DEAs. With an ultra-high power density and lightweight, these soft actuators can run for hundreds of thousands of cycles. 

The team then combined the new dielectric elastomer actuators with a soft channel, which created a soft valve for fluidic control.

Siyi Xu is a graduate student at SEAS and first author of the paper. 

“These soft valves have a fast response time and are able to control fluidic pressure and flow rates that match the needs of hydraulic actuators,” said Xu. “These valves give us fast, powerful control of macro-and small-scale hydraulic actuators with internal volume ranging from hundreds of microliters to tens of milliliters.” 

The researchers used the DEA soft valves to demonstrate control of hydraulic actuators of different volumes. They were able to achieve independent control of multiple actuators powered by a single pressure source.

“This compact and light-weight DEA valve is capable of unprecedented electrical control of hydraulic actuators, showing the potential for future on-board motion control of soft fluid-driven robots,” said Xu. 

Other co-authors of the research included Yufeng Chen, Nak-Seung Patrick Hyun, and Kaitlyn Becker.