Walking on Air

Before assembling a robot, a large variety of parts first has to be collected. Motors, servos, microcontrollers, sensors, grippers, power supplies, frames, joints… the list goes on and on. Nobody ever said robotics was going to be easy. But could it be? Researchers at the University of California San Diego believe that building a robot could be far simpler in the future. And to prove it, they have developed a fabrication process that looks more like a replicator from Star Trek than any traditional process in use today.

A team at the Bioinspired Robotics Laboratory has designed a fully functional walking robot that can be 3D-printed in one piece using a standard desktop 3D printer and a single material. Unlike traditional robots, which rely on complex electronics, this innovative design uses compressed air to power its movements — no motors, batteries, or circuit boards required. The entire robot costs just $20 to produce, requiring only an off-the-shelf printing material and a compressed air canister.

Most soft robots today are made using silicone molding, a process that requires significant manual assembly and expertise. In this work, the team sought to eliminate this difficulty by 3D-printing a six-legged walking robot in one complete piece, integrating artificial muscles and a control system directly into the design.

The key to making this possible is a pneumatic oscillating circuit — essentially a fluidic control system that regulates the movement of the robot’s legs. Inspired by steam locomotives, this circuit controls airflow to alternate pressure between two sets of three legs, creating a rhythmic walking motion. The legs have four degrees of freedom, allowing them to move up, down, forward, and backward, enabling efficient locomotion across various terrains.

Once connected to a steady source of compressed gas, the robot can operate continuously for up to three days. The researchers also tested it outdoors using a portable gas cartridge, demonstrating its ability to traverse different surfaces such as turf and sand — even walking underwater.

Aside from the simplicity of its construction, one of the biggest advantages of an electronics-free robot is its ability to function in extreme environments where traditional electronic systems would fail. These robots could, for instance, explore environments with high radiation, such as nuclear disaster sites, where standard robots would be damaged by radiation exposure. The lack of electronics also makes these robots resistant to extreme temperatures and cosmic radiation, making them well-suited for future extraterrestrial missions.

Despite the success of this project, there is still room for improvement. The team’s future goals include integrating a built-in compressed gas reservoir, eliminating the need for an external power source. Additionally, they are exploring the use of recyclable and biodegradable materials to create more sustainable designs.

From laboratory testing to real-world applications, this work challenges the belief that building robots must be complicated. With just a 3D printer and a cartridge of compressed air, robots may soon be able to walk themselves out of the machine — no assembly required.