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The U.S. Department of Defense challenges CU students to assemble a fleet of robots.

“Robotics requires a team of people, that have such a wide range of knowledge.”

    When you roam around the maze-like corridors in the Engineering Center building, do you happen to encounter robots moving around by themselves? If you saw the one walking on its four legs, then you have met Spot. How about the robot that looks like a Mars rover? That one is Husky. Both Spot and Husky usually carry around some set of equipment on their shoulders. They are two out of a dozen robots that CU students and professors built for a competition held by the Defense Advanced Research Projects Agency (DARPA), part of the US Department of Defense.

    Spot, Husky and the rest of the fleets have been around since 2018 when the DARPA Subterranean challenge started. These robots were designed to work as a team called Multi-Agent Autonomy with Radar-Based Localization for Exploration (MARBLE). The DARPA competition asked participants to create a robot system that can handle challenging underground terrain. In a situation like search and rescue missions, the environments are often too hazardous for human first responders. If you imagine the ruins of a building after an earthquake, the rest of the building can still collapse and this kind of condition can be fatal for humans. For this reason, robots may help us to do the search and rescue function so that we do not put human life in danger. “Search and rescue is a really good application for robots. Even with an ‘only okay’ robot, it is better than sending in a person. We do not want to send a person into a possibly catastrophic situation,” said Mike Miles, a Mechanical Engineering PhD student in the team.

    Moreover, underground exploration is not an ideal environment for a robot. This is where a team of robots can make an impact. Underground terrains, such as tunnel remains and caves, have many obstacles, and the ground itself is often bumpy. If the road is untraversable by the Husky rover, Spot, the legged robot, may be able to walk through. So, one problem is partially solved. The next problem is the communication system to control the robots. Have you ever lived in a basement without Wi-Fi? Did you get good cell reception? I doubt so. Radio waves, which is a generic term for electromagnetic waves that are used for communication, do not travel well through thick solid matter like an underground compartment. For a quick comparison, an airplane pilot can talk with an air traffic control officer from miles away.

    This condition happens because radio waves propagate well in the air. The ���񱦵� MARBLE team decided to create an ingenious system. Their solution involves combining some beacons to relay the communication signals between the human operator and the robots themselves in order The U.S. Department of Defense challenges CU students to assemble a fleet of robots. to sense and send the message back to the system. Let’s say Husky found a chamber that is too difficult to pass through. If Spot is in communication proximity, Husky can send a message directly to Spot so that Spot can come cover to check the chamber. But, if Spot is too far away, Husky will send the signal through the beacon-relay system that has been planted by the robots during exploration. What happens if the communication system gets interrupted and disconnected? The robots are programmed to have some autonomy to decide their next moves, but it all depends on circumstances.

    In the real DARPA challenge, the tasks that the robots were needed to do were even more complex. In preparation, the MARBLE team tried to get their fleet of robots ready to tackle any possible problem throughout the competition. Miles explained that such a simple task can be tough to do in an underground setting. Miles worked on developing the origin detection process of the system. Typically, we can rely on GPS to tell where we are on earth. Unfortunately, inside the earth, the GPS signal would not work. So, additional measures were done by Miles so that the robots can locate themselves underground.

    In the DARPA Challenge, one of the tasks is to find and identify objects in order to simulate real-world conditions. When looking for a missing person in a collapsing underground mine, we may need to locate tools left by mine workers, such as shovels or pickaxes. The MARBLE robots have been equipped with cameras and algorithms to do this particular job. But this autonomy is often not enough. “As the competition went on, we kept adding more elements of human supervision. It turns out it ends up being the turning point for us in the competition. The reason that we did really well in the competition is because of the changes that we made on the last day where we gave the human supervisor more capability to take more control of the robots,” explained Dan Riley, a Computer Science PhD student working in the MARBLE team. The field conditions can be unpredictable, and helping the robots make decisions can do wonders. Riley, who has more than a decade of experience in the US Air Force, became the human operator to manage the robots in the final competition. With this last-minute modification of the system, the MARBLE team was able to identify many artifacts, an achievement that eventually won them third place in the competition.

    Undergraduate students also took important roles in the MARBLE team. Daniel Torres joined the team when he was a senior in Mechanical Engineering. Torres led “Robotics requires a team of people, that have such a wide range of knowledge.” the hardware design and development of the robots. “Ever since we started, I really like what we did. I would like to stay on the team,” said Torres. He decided to continue his education at CU as a graduate student in Computer Science and he remains a committed member of the team. Drew Beathard, who is a senior in the Creative Technology Design program, has a unique position in the project. Before joining the team, Beathard was looking for an internship with companies for the summer. With limited internship opportunities, he decided to look for hands-on experience he could find on campus. Beathard reached out to Prof. Christoffer Heckman, who is one of the principal investigators of the MARBLE team, asking for a possible project to be involved in. After months in the project, Beathard said, “I could not have asked for a better assignment.” He used many of his skills acquired from classes he has taken, such as rapid prototyping and computer-aided design. Beathard’s involvement has kept him fascinated by working with robots. “I think it is the perfect combination of all kinds of engineering together. Robotics requires a team of people who have such a wide array of knowledge” added Beathard. Now that the competition is done, Beathard is determined to continue some of his work for his Capstone project for his degree.

    There are many interesting things to learn from the MARBLE robots and the team itself. One thing for sure is that a single robot may fail in the field, but a team of robots can be more robust in managing difficult environments. Depending on the situation, human involvement can have a significant benefit on autonomous robot performance. And after all, everyone’s experience in the team has been remarkable. Undergraduates who want to get hands-on experience related to their degree can consider working with CU engineers on campus to create next-generation technology for humankind.

Photos courtesy of the marble team