The robot is powered only by a cartridge of compressed gas - directly off a 3D printer and printed once from a single material.
Using Simple 3D Printing Technology for Robotics
Researchers used a desktop 3D printer and an off-the-shelf printing material, with each robot costing about $20 to manufacture.
“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.
Potential Applications in Extreme Environments
These robots could be deployed in environments where electronics cannot function. For example, they could support scientific reconnaissance in areas with strong radiation, disaster response, or space exploration.
In laboratory tests, researchers demonstrated that as long as the robots remained connected to a source of air or gas under constant pressure, they could function continuously for three days.
The robots walked outdoors, untethered, using a compressed gas cartridge as a power source.
They moved over different surfaces, including turf and sand, and even walked underwater.
Printing Flexible Robots with Soft Materials
The goal was to design robots that could walk straight off the printer with only an air power source while utilising flexible, soft materials.
“These robots are not manufactured with any of the traditional, rigid components researchers typically use,” Tolley said. Instead, they are made from a simple 3D printing filament.
A major challenge was creating a design that incorporated artificial muscles and a control system, all printed from the same soft material in a single print. The research team, led by postdoctoral scholar Yichen Zhai at the UC San Diego Jacobs School of Engineering, adapted a 3D printing technique previously used to build an electronics-free gripper.
The result was a six-legged 3D printed walking robot. “We have taken a giant leap forward with a robot that walks entirely on its own,” Zhai said.
Innovative Pneumatic Oscillating Circuit for Movement
To drive the robots, the team designed a pneumatic oscillating circuit that controls the repeated motions of soft actuators, similar to the mechanism powering a locomotive’s steam engine.
The circuit coordinates the movement of the six legs by delivering air pressure at precise intervals, alternating between two sets of three legs. The robot’s legs can move in four degrees of freedom—up and down, forward and back—allowing it to walk in a straight line.
Future Advancements: Storage and Sustainability
Next steps for the research include developing ways to store compressed gas inside the robots and utilising recyclable or biodegradable materials. The team is also exploring the integration of manipulators, such as grippers, into the robots.
Tolley’s lab collaborated with BASF through the California Research Alliance (CARA) to test various soft materials compatible with standard 3D printers. Some of the high-end materials tested are not yet commercially available, but researchers successfully printed the robots using off-the-shelf standard materials.
Collaboration and Research Funding
In addition to working with BASF, the research received partial funding from the National Science Foundation.
Prior to this publication, the research team completed the 3D printed walking robot in 2022 and showcased it at that year’s Gordon Research Conference on Robotics.
