Researchers develop gas powered 3D-printed robot

The team from the Bioinspired Robotics Laboratory at the University of California San Diego built their six-legged robot with a desktop 3D-printer and an off-the-shelf printing material at a cost of around $20. Their work is described in Advanced Intelligent Systems.

“This is a completely different way of looking at building machines,” said Michael Tolley, a professor in the UC San Diego Department of Mechanical and Aerospace Engineering and the paper’s senior author. 

The researchers tested the robots in the lab and showed that as long as they were connected to a source of air or gas under constant pressure, they could function non-stop for three days. The team also showed that the untethered robots could traverse different surfaces, including turf, sand, and underwater.

 “These robots are not manufactured with any of the traditional, rigid components researchers typically use,” Tolley said in a statement. Instead, they are made of simple 3D-printing filament.

According to the roboticists, the biggest challenge was creating a design that would include artificial muscles, and a control system printed from the same soft material, in a single print. 

Led by postdoctoral scholar Yichen Zhai in Tolley’s research group at the UC San Diego Jacobs School of Engineering, the team adapted a 3D printing technique that they used previously to build an electronics-free gripper to develop the robot.

“We have taken a giant leap forward with a robot that walks entirely on its own,” said Zhai.

For movement, the team created a pneumatic oscillating circuit to control the repeated motions of soft actuators. The circuit coordinates the movement of the six legs by delivering air pressure at the right time alternating between two sets of three legs. The robots' legs can move in four degrees of freedom—up and down, forward and back, which allows the robot to walk in a straight line. 

Next steps include finding ways to store the compressed gas inside the robots and using recyclable or biodegradable materials. The researchers are also exploring ways to add manipulators, such as grippers, to the robots.

Tolley’s lab partnered with the BASF corporation through their California Research Alliance (CARA) to test various soft materials that could be used on standard 3D printers. Some of the high-end materials they tested are not commercially available, but the researchers also printed the robots with off-the-shelf, standard materials. 

In addition to their collaboration with BASF, the work was partially funded by the US National Science Foundation.