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Radiation and Robots: Saving Lives Through Technology

Robots are increasingly being designed to stand in for humans when responding to both law enforcement and public health emergencies.

However, in the wake of the 2011 Japanese Fukushima nuclear power plant disaster, it became glaringly clear robotic technology must vastly improve if it is going to save more lives.

When it comes to understanding the effects of radiation on robotic motors, researchers at The Ohio State University are doing their part.

Electrical and Computer Engineering Department (ECE) PhD student Hongfei Wang is the principal investigator behind research recently published in IEEEXplore, which seeks to equip robots with the proper technology to withstand the damaging power of radiation. ECE co-authors include fellow PhD student Shimeng Li and advising professor Yuan Zheng.

Wang’s research, “Analysis of Radiation effects on DC Motorized Manipulator,” is in response to the larger call to action issued out by the U.S. Defense Advanced Research Projects Agency (DARPA).

As Scientific American reported, “after a small squadron of robots was sent to assist workers at the devastated Fukushima Daiichi nuclear plant. The machines spent a good deal of time on the sidelines, leaving humans to do the most hazardous work.”

Thirty years ago, attempts to send industrial robots into the Chernobyl nuclear reactor accident area were similarly ill-conceived.

In his research, Wang explains that while the impact of radiation on electrical circuits is well studied, how it affects the performance of robotic motors remains unchartered territory. Robotic motors are both magnetic and electrical in structure, revealing the inherent flaw from shielding the machinery against radiation.

In theory, Wang said, researchers know radiation displaces atoms, which leads to ionization in semiconductor materials. This essentially demagnetizes the servo control systems preferable in robotic movement.

“Experimental results indicated that both charged particles (protons and electrons) and neutron radiation have significant impact on the magnetic properties of ferromagnetic materials at a certain dose,” he said. “If we send it into a radioactive environment, the radiation will damage the structure of the motor.”

To further understand this process, Wang said, his research utilizes stochastic modeling – a tool for estimating probability and potential outcomes.

“Through the study of a stochastic model, we can estimate what are the extreme damages brought by radiation,” Wang said. “So, the ultimate goal is to ensure the motor works no matter which special case of the stochastic model is the radiation result.”

However, how does a scientist test and predict such theories?

Wang said there is a reason why engineers simply can’t head into a radioactive environment do testing until they get it right.

“It’s expensive,” he said.

Instead of recreating the environment, algorithms are designed to simulate the different effects on the robot, especially how different levels of radiation impact functionality.

“We are engineering the robots to move and do activities,” he said. “The applications for the technology can mean removing humans from dangerous situations, to be replaced by a robot whose make-up is more conducive to the environment.”

The new research is a continuation of previous ECE work to improve robotic movement over adverse conditions, assisting in emergency response.

While it may take years before emergency response robots become fully autonomous, mobile and dexterous machines, the DARPA Robotics Challenge was created to give scientists an incentive to keep moving forward. Meanwhile, NASA is conducting similar work through the Radiation Hardened Electronics for Space Environments project.