Emergency-response robots have long suffered from having a range of mobility and dexterity comparable to a one-year-old child and a level of autonomy generally limited to completing a single task at a time. Nowhere was this more painfully obvious than in Japan four years ago, 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.

The world will see just how far robots have advanced in the subsequent years when the U.S. Defense Advanced Research Projects Agency (DARPA) hosts the final round of a robotics competition aimed at building autonomous machines that can step—or roll—in when disasters strike. A total of 25 international teams will compete June 5 and 6 to win one of three cash prizes totaling $3.5 million.

The winning robots will complete eight different tasks on a DARPA obstacle course in the shortest amount of time. The course is designed to simulate a disaster area too dangerous for humans to enter. As an added challenge, DARPA will deliberately degrade communication links between robots and operators for each team as it competes in order to create a scenario closer to the one responders experienced in Fukushima.

When robots arrived in Fukushima in March 2011, they found the facility contaminated by radiation and deluged by tons of corrosive seawater. A magnitude 9.0 undersea earthquake had created a tsunami, which pushed massive amounts of ocean water into the plant and disabled the emergency generators required to cool the nuclear reactors. The following three weeks featured meltdowns, gas explosions and radiation leaks that worsened the situation.

Responders soon found that the need for radiation shielding on the robots, in combination with other factors, created disruptions in communication that left the machines operating without instruction for periods of time. Robots from iRobot and Honeywell—both of which had been developed using DARPA funds—eventually did help with some damage assessment and cleanup—and some continue to operate at Fukushima—but they were of limited use during the emergency when the site was at its most dangerous.

The previous round of the DARPA Robotics Challenge required robots to engage an emergency shutoff switch, get up from a prone position, travel 10 meters without falling, pass over a barrier and rotate a circular valve 360 degrees. The final competition will feature similar—but not the same—challenges so that teams are forced to demonstrate some flexibility and cannot script all of their robot’s moves ahead of time.

Robots may not be recharged while competing nor are teams allowed to rig their bots with hoists or safety ropes to prevent falls. If a robot falls and cannot get up, the team takes a 10-minute penalty and a rescue bot is sent onto the course to retrieve their original unit so that it can try again. During the competition, each team will operate out of a garage area far from the test course. The only information they will have about their robot and its surroundings will come from the machine’s own onboard sensors.

Overall, the challenge aims to develop versatile machines that can be deployed during any emergency and present a very short learning curve for operators. “Fukushima was really a great inspiration for us because we don’t know what the next disaster is going to be, but we know that we have to develop technology to help us to address these kinds of disasters,” Gill Pratt, DARPA program manager for the competition, said Wednesday during a press conference. Earlier intervention—while keeping responders at a safe distance—could help keep future disasters from escalating as Fukushima did, he added.

Regardless of which robot takes home the big purse, there is still a long way to go before machines can operate autonomously in unpredictable environments such as those found when disaster strikes. “The robots that you’re going to see at the challenge are very far from fieldable systems” that could be sent into a situation such as earthquake-stricken Nepal, Pratt said.

The development of fully mobile, dexterous, multitasking machines that can serve as fully functioning responders will take many years. In the meantime DARPA’s competition gives roboticists an incentive to keep moving in that direction.