Metal-Eating Robot Can Follow Metal Path With No Computer or Battery

A newly developed ‘metal-eating’ robot can follow a metal path with no need for a computer or battery. The robot can autonomously navigate towards aluminum surfaces and away from hazards thanks to the power-supplying units being wired to the wheels on the opposite side.

Batteries are one of the major barriers in the field of robotics. The more energy they have, the heavier the weight. This weight means the robot must also have more energy to move, and while some power sources like solar panels are useful in some applications, there needs to be a more consistent, quick, and sustainable way.

James Pikul is an assistant professor in Penn Engineering’s Department of Mechanical Engineering and Applied Mechanics. He is currently developing the new technology by relying on an environmentally controlled voltage source, or ECVS, instead of a battery.

With an ECVS, energy is produced by breaking and forming chemical bonds, and it is able to keep the weight down by finding the chemical bonds in the robot’s environment. The ECVS unit catalyzes an oxidation reaction with surrounding air when it comes into contact with a metal surface, and this is what powers the robot. 

Pikul drew inspiration from nature, specifically looking at how animals forge chemical bonds in the form of food as a source of power. Even without a ‘’brain,” these new ECVS-powered robots are also searching for their food source.

The new study was published in Advanced Intelligent Systems. 

Pikul was joined by lab members Min Wang and Yue Gao, and the team demonstrated how the ECVS-powered robots could navigate the environment without the need of a computer. The left and right wheels of the robot are powered by different ECVS units, and they demonstrate basic navigation and foraging abilities as the robot automatically moves towards and “eats” metallic surfaces.

The study didn’t just stop there, as it also demonstrated how more complicated behavior could be achieved without a central processor. The robot can perform different logical operations depending on its food source, which is achieved by having different spatial and sequential arrangements of the ECVS units.

“Bacteria are able to autonomously navigate toward nutrients through a process called chemotaxis, where they sense and respond to changes in chemical concentrations,” Pikul says. “Small robots have similar constraints to microorganisms, since they can't carry big batteries or complicated computers, so we wanted to explore how our ECVS technology could replicate that kind of behavior.”

Testing the Robot

The researchers tested the new robot by placing it on an aluminum surface that can power its ECVS units, and they then added “hazards” that would break the contact between the robot and the metal. In the experiments, the ECVS units were able to move the robot and navigate it towards energy-rich sources.

“In some ways,” Pikul says, “they are like a tongue in that they both sense and help digest energy.”

One of the hazards used by the team was a curving path of insulating tape, and by wiring the ECVS units to the wheels on the opposite side, the robot could autonomously follow the metal lane in between two lines of tape. For example, the ECVS on the right would lose power first if the lane curved to the left, which causes the robot’s left wheels to slow and move away from the hazard.

The team also used a viscous insulating gel as a hazard, and the robot was able to slowly wipe it away while driving over it. The design of the robot can now be improved as researchers learn what the ECVS can pick up, and these can be incorporated into the design of it. 

“Wiring the ECVS units to opposite motors allows the robot to avoid the surfaces they don't like,” says Pikul. “But when the ECVS units are in parallel to both motors, they operate like an ‘OR' gate, in that they ignore chemical or physical changes that occur under just one power source.”

“We can use this sort of wiring to match biological preferences,” he says. “It's important to be able to tell the difference between environments that are dangerous and need to be avoided, and ones that are just inconvenient and can be passed through if necessary.”

Autonomous and computerless robots will be able to undertake more complex behaviors as ECVS technology evolves, and the surrounding environment will play a big role in the ECVS design. For example, tiny robots could be developed to navigate dangerous and tight environments.

“If we have different ECVS that are tuned to different chemistries, we can have robots that avoid surfaces that are dangerous, but power through ones that stand in the way of an objective,” Pikul says.