Rather than carrying a heavy onboard battery, the robot is powered using an environmentally controlled voltage source, or ECVS. While in contact with a metal surface, the ECVS unit catalyses an oxidation reaction with the surrounding air, essentially ‘eating’ the metal and powering the robot with the freed electrons.
In a paper published in Advanced Intelligent Systems, the Penn State team describes how the left and right wheels of the robot are powered by different ECVS units. This enables a basic form of navigation and foraging where the robot will automatically steer toward metal surfaces it can harvest power from, without assistance from a computer. The rudimentary form of navigation takes inspiration from the natural world, according to the team.
"Bacteria are able to autonomously navigate toward nutrients through a process called chemotaxis, where they sense and respond to changes in chemical concentrations," said James Pikul, assistant professor in Penn Engineering's Department of Mechanical Engineering and Applied Mechanics.
"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 behaviour."
In their experiments, the team placed the metal-eating robot on aluminium surfaces capable of powering its ECVS units. By adding ‘hazards"’ that would prevent the robot from making contact with the metal, they showed how ECVS units could both get the robot moving and navigate it toward more energy-rich sources.
As ECVS technology evolves, Pikul and his colleagues believe it can be used to program more complicated and responsive behaviours in autonomous, computerless robots. By matching the ECVS design to the environment that a robot needs to operate in, they envision tiny robots that crawl through rubble or other hazardous environments, getting sensors to critical locations while preserving themselves.
"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," said Pikul.