Multirotor drones excel at vertical lift and hover, while fixed wing drones are great at both distance and wide-open spaces. In February, Auterion Government Solutions and Quantum-Systems announced a two-pronged approach to the rotor- or fixed-wing drone market, with a pair of drones that use the same sensor packages and fuselage to operate as either the Scorpion Trirotor or the Vector fixed wing craft.

“As we started to develop our tactical UAS Platform, our plan was only to develop a VTOL fixed wing solution (like our Vector),” said Florian Siebel, managing director of Quantum-Systems. “During the development process we decided to build a Tri-Copter Platform as well, as a result of many discussions with law enforcement agencies and Search and Rescue Units.”

Adapting the fixed-wing fuselage to the tri-copter attachments means the drone can now operate in narrow spaces and harsh conditions. Scorpion, with the rotors, can fly for about 45 minutes, with a cruising speed of zero to 33 mph. Put the fixed wings back on for Vector, and the flight time is now two hours, with a cruising speed of 33 to 44 mph.

The parts snap into place without any need for special tooling, and Auterion recommends the drone for missions in rain or snow. Both platforms share a gimbal EO/IR with 10x optical zoom, 720p EO video, 480p IR video, laser illuminator, IR laser ranger. Common between modes is also a tactical mapping tool using a 21 megapixel Sony UMC R10C camera. For the scorpion, there’s also the option of a gimbaled electro-optical camera with a 30x optical zoom.

Both drones are designed to fit in rucksacks that a person can carry one at a time. While many features are common across Vector and Scorpion, the plan is not to include both rotors or wings in the same kit. Once a team packs into the field with a drone on its back, that’s the mode the drone can be used in.

Auterion intends to ship the drones by the fourth quarter of 2020, with preorders available.

Designing a drone body is about settling on the right compromise. Vector and Scorpion are built on top of open source code. This includes an operating system capable of programmable autopilot , as well as machine-vision collision prevention and obstacle detection and avoidance. Software for the ground station and cloud data management of the drone are also built on open source code. The Pentagon’s Defense Innovation Unit awarded Auterion a $2 million contract last year to work on the PX4 software to help drive compatibility standards in the drone industry.

As militaries across the world look to the enterprise sector for capable drones at smaller profile than existing military models, transparency in code and flexibility in airframe could become more widely adopted trends. In the meantime, there is Vector, and there is Scorpion.

Outside the compound on Oct. 26, waiting and at the ready, was a robot.

The vested man was later identified as Abu Bakr Al-Baghdadi, the self-proclaimed caliph of the Islamic State of Syria and the Levant.

“We had a robot just in case because we were afraid he had a suicide vest and if you get close to him and he blows it up, you’re going to die. You’re going to die. He had a very powerful suicide vest,” President Donald Trump said in a press conference about the raid in the following days.

“The robot was set, too, but we didn’t hook it up because we were too — they were moving too fast. We were moving fast,” the president continued. “We weren’t 100 percent sure about the tunnel being dead ended. It’s possible that there could have been an escape hatch somewhere along that we didn’t know about.”

In this case, the robot never went in the tunnels.

Picture the scene, four months later, in the damp subterranean levels of the never-finished Satsop nuclear power plant outside Elma, Washington. There, engineers and scientists are testing the machines and algorithms that may guide missions for a time, preparing for a time when the robots won’t remain on the sidelines.

None of the robots fielded at the Defense Advanced Research Projects Agency’s Subterranean Challenge urban circuit in Elma in February are particularly battle-ready, though a few could likely work in a pinch.

Apart from a single human commander able to take remote control, the robots navigate, mostly autonomously. As captured on hours of video, the robots crawled, floated, rolled and stumbled their way through the course. They mapped their environment and searched for up to 20 special artifacts in the special urban circuit courses, built in the underground levels around a never-used cooling tower.

The artifacts included cellphones emitting bluetooth, Wi-Fi and occasionally video. They included red backpacks and thermal manikins warmed to the temperature of humans playing an audio recording, and they included carbon dioxide gas and warm blowing vents.

This urban circuit is the second of three underground environments that DARPA is using to test robots. Phones, manikins and backpacks are common across the tunnel, urban and cave settings that constitute the full range of subterranean challenges. The straightforward mission of the contest is to create machines that are better at rescue in environments that are dangerous and difficult for first responders, who are humans. If robots can find people trapped underground, then humans can use their energy getting to those same people, rather than expend that energy searching themselves.

A subtext of the Subterranean Challenge is that the same technologies that lead robots to rescue people underground could also lead infantry to find enemies hiding in tunnel complexes. While Delta Force was able to corner al-Baghdadi in Syria, much of the military’s modern interest in tunnel warfare can be traced back to Osama bin Laden evading capture for years by escaping through the tunnels at Tora Bora.

Underground at Satsop, the future of warfare was far less a concern than simply making sure the robots could navigate the courses before them. That meant, most importantly, maintaining contact with the other robots on the team, and with a human supervisor.

Thick concrete walls, feet of dirt, heavy cave walls and the metals embedded in the structure all make underground sites that the military describes as passively denied environments, where the greatest obstacle to communication through the electromagnetic spectrum is the terrain itself. It’s a problem military leaders, particularly in the Army, are hoping to solve for future iterations of their networks.

Team NUS SEDS, the undergrad roboticists representing the National University of Singapore Students for Exploration and Development of Space, arrived in Washington with one of the smallest budgets of any competitor, spending roughly $12,000 on everything from robot parts to travel and lodging. One of their robots, a larger tracked vehicle, was held up by U.S. Customs, and unable to take part in the competition.

Not to be deterred, at the team’s preparation area, members showed off a version of the most striking design innovation at the competition: droppable Wi-Fi repeaters. As designed, the robots would release a repeater the moment they lost contact with the human operator. To lighten the data load, the onboard computers would compress the data to one-hundredth of its size, and then send it through the repeater.

“It’s like dropping bread crumbs,” said Ramu Vairavan, the team’s president.

Unfortunately for NUS SEDS, the bread crumbs were not enough, and the team only found one artifact in its four runs between the two courses. But the bread-crumb concept was shared across various teams.

Besides the physical competition taking place underground at Satsop, the urban circuit held a parallel virtual challenge, where teams selected robots and sensors from a defined budget and then programmed algorithms to tackle a challenge fully autonomously. The repeaters, such a popular innovation in the physical space, will likely be programmed into the next round of the virtual challenge.

The first DARPA Grand Challenge, launched in 2004, focused on getting roboticists together to provide a technological answer to a military problem. Convoys, needed for sustaining logistics in occupied countries, are vulnerable to attack, and tasking humans to drive the vehicles and escort the cargo only increasing the fixed costs of resupply. What if, instead, the robots could drive themselves over long stretches of desert?

After much attention and even more design, the March 2004 challenge ended with no vehicle having gone even a tenth the distance of the 142-mile track. A second Grand Challenge, held 18 months later, delivered far more successful results, and is largely credited with sparking the modern wave of autonomous driving features in cars.

Open desert is a permissive space, and navigation across it is aided by existing maps and the ever-present GPS data. This is the same architecture that undergirds much of autonomous navigation today, where surface robots and flying drones can all plug into communication networks offering useful location data.

Underground offers a fundamentally unknowable environment. Robots can explore parts of it, but even the most successful team on its most successful run found fewer than half of the artifacts hidden in the space. That team, CoSTAR (an acronym for “Collaborative SubTerranean Autonomous Resilient robots) included participants from Jet Propulsion Laboratory, CalTech, MIT, KAIST in South Korea and Lulea University of Technology in Sweden. CoSTAR used a mixture of wheeled and legged machines, and in the off-hours would practice everywhere from a local high school to a hotel staircase.

Yet, for all the constraints on signal that impeded navigation, it was the human-built environment that provided the greatest hurdle.

On a tour of the courses, it was easy to see how an environment intuitive to humans is difficult for machines. Backpacks and cellphones were not just placed on corners of roofs, but on internal ledges, impossible to spot without some aerial navigation.

Whereas the tunnel course held relatively flat, the urban circuit features levels upon levels to explore. Stairs and shafts, wide-open rooms with the jangly mess of a mezzanine catwalk, all require teams and robots to explore space in three dimensions. Between runs, the humans running the competition would adjust some features, so that completing the course once does not automatically translate into perfect information for a second attempt.

“How do we design equally hard for air and ground?” Viktor

Orekhov, a DARPA contractor who designed the course, said. “There’s an art to it, not a science. But there’s also a lot of science.”

Part of that art was building ramps into and out of an early room that would otherwise serve as a run-ending chokepoint. Another component was making sure that the course “leveled up” in difficulty the further teams got, requiring more senses and more tools to find artifacts hidden deeper and deeper in the space.

“Using all senses is helpful for humans. It’s helpful for robots, too,” said Orekhov.

Teams competing in the Subterranean Challenge have six months to incorporate lessons learned into their designs and plans. The cave circuit, the next chapter of the Challenge scheduled for August 2020, will inevitably feature greater strain on communications and navigation, and will not even share the at least familiarity of a human-designed spaces seen in the urban circuit. After that, teams will have a year to prepare for the final circuit, set to incorporate aspects of tunnel, urban and cave circuits, and scheduled for August 2021.

DARPA prides itself on spurring technological development, rather than iterating it in a final form. Like the Grand Challenges before it, the goal is at least as much to spark industry interest and collaboration in a useful but unexplored space.

Programming a quadcopter or a tracked robot to find a manikin in a safety-yellow vest is a distant task from tracking and capturing armed people in the battlefields of the future, but the tools workshopped in late nights at a high school cafeteria between urban circuit runs may lead to the actual sensors on the robots brought along by Delta Force on future raids.

The robots of the underground wars of tomorrow are gestating, in competitions and workshops and github pages. Someday, they won’t just be brought along on the raid against a military leader.

Wordlessly — with spinning LiDAR, whirring engines, and millimeter-wave radar — the robots might lead the charge themselves.

The attack, which featured multiple remotely piloted drones pursuing the same objectives, is a reminder that the capacity to launch drone strikes is hardly limited to superpowers. Turkey’s drone program has developed, over years, several armed drones that are rough analogs to American-operated models like the Reaper, Predator and Shadow.

“This was a mass coordinated attack, not a ‘swarm’ — ‘swarm’ implies autonomous capabilities and UAVs coordinating among themselves,” said Samuel Bendett, an adviser at the Center for Naval Analyses.

While swarming autonomy remains a research project for nations, even such a labor-intensive operation as the mass use of remotely piloted drones offers advantages over flying human-occupied vehicles on the same missions.

“Given a very complicated battleground in Syria — where Syrian and Russian air defenses protect key assets, and where Iranian forces operate alongside their Assad allies — Turkey’s decision to send a mass coordinated UAV attack points to its availability of options,” said Bendett. “Rather than send a piloted aircraft that could be lost, with the pilot killed, Turkey sent unmanned systems, whose loss is less profound and does not ultimately impact Turkish military capability. Turkey is also able to gather key intel on Syrian air defenses, especially those that managed to down Turkish UAVs.”

Those Syrian air defenses were about to shoot down at least seven drones, including at least one Anka-S, priced at tens of millions of dollars. The attack was not without cost to Turkey, but despite the damage inflicted by anti-air defenses, the drones were still able to hit their targets. Defending against drone operations may mean adopting different tools than those used to deter human incursions.

Turkey stood up its drone industry in light of a prohibition from the United States on purchasing armed drones, and since then has also developed those military drones for export. Those drones, like the Bayraktar, have been explored to Ukraine and Libya. Turkey has even reached out to Ukraine for engines to power a long-range drone.

With the capabilities of its drones proven in combat, Turkey joins the United States, United Kingdom, France, Israel, China and Iran as drone-armed nations. A swarm the recent strike was not, but for the people targeted on the ground, a remotely piloted salvo is just as deadly a proposition.

For military planners who fear future conflicts in megacities, Elma provides a near-ideal testing ground: an urban environment without the difficulties of an inhabited space.

This week, the Satsop business park outside the city was host to the next chapter of the Subterranean Challenge by the Defense Advanced Research Projects Agency. The explicit goal of the event was to “develop innovative technologies that would augment operations underground.” In practice that means testing robots, often teams of robots, and the software to navigate unknown environments. Mapping is a necessary but insufficient part of the process. For the challenges, the robots must locate specific artifacts, and then record their position within 5 meters.

The event, which C4ISRNET attended, offers prize money, but also a way to help ensure the military will one day have the technology it needs.

“There are a lot of different types of what it means to be urban underground,” said Timothy Chung, DARPA program manager for the Subterranean Challenge. “We came to Satsop because it was a perfect blend of challenging environment, and one that supports scale of event and makes use of local resources.”

A Titan vehicle from team CSIRO, with a DJI Matrice 210 quadcopter mounted on its back, rolled into the cold, damp, dark void of the beta course at the urban circuit of the challenge. As it moved forward and returned information, rendered maps, once blank, filled in.

“We want actionable situational awareness,” Chung said. “What is the nugget of information that the commander would make use of?”

Consider the robots exploring the underground passages at Satsop. A power plant is exactly the kind of complex space built for human passage — one where, in the event of a disaster, it would be safer to send a robot in first.

Some of the artifacts the robots needed to find were common across all three of the Subterranean Challenges’ environments (which include a tunnel, held in August 2019; an urban setting, held in February; and a cave, to be held in August 2020). These artifacts included red backpacks; cellphones, sometimes playing video; and thermal manikins that gave off the heat signature of a human and had speakers playing “welcome to the Subterranean Challenge.”

In addition, the urban circuit featured heated vents blowing air, and canisters releasing carbon dioxide, as a stand-in for more dangerous gasses. The mix of artifacts required a range of technologies to detect what was happening, with everything from visual confirmation to gas sniffers to Wi-Fi readers. Teams used these tools as a way to approximate the best way for robots to provide useful information that first responders would need if they followed robots into a dangerous space.

Satsop featured two courses on the urban circuit with each run of the course is limited to one hour. To prevent teams from simply guessing that every possible inch of mapped space is one of the 20 artifacts on the course, teams are limited to a total of 40 guesses per run. Between runs, teams were welcome to make modifications, adapt existing machines to discover constraints and save map information, with the understanding that parts of the course may change between runs.

One such field modification was the conversion of an uncrewed blimp into a more dirigible-bodied craft. Team NCTU (from Taiwan National Chiao Tung University) created a pair of blimps called “Duckiefloats,” designed to float up and explore the vertical spaces inside the courses at Satsop. A novel creation, the bodies proved too wide on initial runs, so the engineers removed the protective cage from the undercarriage holding the electronics and taped on a simple lattice of carbon-fiber rods to give the airships a narrower, more door-shaped profile, shrinking the width to about 90cm.

Another innovation, in varying forms, was using robots to release smaller fixed communication relay nodes. With antennas and power supplies, the various relays allowed a robot to send its signal further back through the signal-hostile environment. Points were not awarded if the robot cannot relay its findings to the human supervisor, so signal integrity is an important part of the process.

The dropped relays are so novel, and so widespread, that the virtual track of the Subterranean Challenge is working on incorporating them in its model for the upcoming cave circuit. In the virtual competition, teams select robots and sensor packages from a predefined budget of points. With robots selected, the virtual teams then code autonomous navigation to the robots and run the robots through practice courses until they feel the algorithms are ready. Once submitted, the code is run through the virtual challenge courses without further modification.

The urban circuit of the Subterranean Challenge is ongoing, with winners of the physical and virtual components to be announced Feb. 27. Self-funded teams are eligible for cash prizes, with $1.35 million in prizes to be awarded across both the physical and virtual tracks.

Seventeen minutes into its run on Beta Course, CSIRO’s quadcopter lifted off the back of the Titan. Tentatively, cautiously, it explored the room it was in. Then, finding an open shaft, it descended into the void, ready to map out actionable intelligence on the subterranean site but also a path forward for robotic assistance.

With thick, concrete walls, a controlled points of access, and the possibility for ambush by infantry and armed vehicles, parking garages in urban combat can serve as makeshift fortifications, hiding a great deal of future pain inside.

To spare the lives of humans, exploring such buildings is a task best done by robots. Yet the interiors of buildings, especially such massive stone-and-metal artifice, can make it difficult for GPS navigation and radio control.

One possible solution comes from Exyn Technologies, which announced this week that it has built code to allow drones to fly in and map a GPS-denied environment. Exyn calls this mission behavior “Scoutonomy,” to really drive home that it lets small drones scout, autonomously.

“These aerial robot systems sense and detect their surroundings in real-time to rapidly gather critical information—including high-fidelity 3D maps and human and object detection—for superior situational awareness,” the company said in an announcement.

That process involves small drones flying and mapping in real-time, creating a useful picture of the world around them which both the drones and humans can use to understand the space. It includes the ability to detect and navigate around obstacles in the area being mapped, such as people or vehicles.

Consider a group of soldiers fighting in a city in the future. Spotting a tall building with open windows on the edge of their route, the soldiers could send the scout robot to fly in, map the space, and most importantly, identify any people or threats found inside. Provided the robot is able to transmit out the information it gathers, that map could let humans on foot or future robots do a more thorough search, and could tell the soldiers if they need to take the building to eliminate a threat, or if they can operate as though it is unoccupied.

Away from the flash and danger of combat, the same scouting protocols could let drones explore buildings in a disaster response scenario, finding people who need rescuing without jeopardizing the lives of human rescuers in the process.

If urban and underground spaces are the battlefields of the future, robots that can map them in real-time will be an invaluable asset. “Scoutonomy” is one possible path, not just to greater battlefield situational awareness, but to R2-D2 (Reconnaissance, Routing, Detection, Determination).

Watch a drone with “Scoutonomy” explore a parking garage below:

Conducted at Camp Shelby Joint Forces Training Center, the exercise was the third test of DARPA’s OFFensive Swarm-Enable Tactics (OFFSET) program. OFFSET is explicitly about robots assisting humans in fighting in urban areas, with many robots working together at the behents of a small group of infantry to provide greater situational awareness than a human team could achieve on its own.

The real-time nature of the information is vital to the vision of OFFSET. It is one thing to operate from existing maps, and another entirely to operate from recently mapped space, with continuing situational awareness of possible threats and other movement through the space.

Dating back to at least 2017, OFFSET is in part an iterative process, with contractors competing for and receiving awards for various ‘sprints,’ or narrower short-turnaround developments in coding capabilities. Many of these capabilities involve translating innovations from real-time strategy video games into real life, like dragging-and-dropping groups units to give them commands.

For the exercise at Camp Shelby, the swarms involved both ground and flying robots. These machines were tasked with finding specific items of interest located in buildings at Camp Shelby’s Combined Arms Collective training Facility. To assist the robots in the field experiment, organized seeded the environment with AprilTags. These tags, which are similar to QR codes but trade complexity of data stored for simplicity and robustness in being read at difference, were used to mark the sites of interest, as well as hazards to avoid.

In practical use, hazards seldom if ever arrive with barcodes explicitly labeling themselves as hazards, but for training the AprilTags provide a useful scaffolding while the robots coordinate in other ways.

“As the swarm relayed information acquired from the tags,” wrote DAPRA, “human swarm tacticians adaptively employed various swarm tactics their teams had developed to isolate and secure the building(s) containing the identified items.”

That information is relayed in various ways, from updated live maps on computer screens to floating maps displayed in real time in augmented reality headsets.

As foreshadowed by countless works of cyberpunk fiction, these “human swarm tacticians” interfaced with both the real world and a virtual representation of that world at once. Commanding robots to move in real space by manipulating objects in a virtual environment, itself generated by robots exploring and scouting the real space, blurs the distinction between artificial and real environments. That these moves were guided by gesture and haptic feedback only further underscores how deeply linked commanding robots can be to augmented reality.

The gesture and haptic feedback command systems were built through sprinter contracts by Charles River Analytics, Inc., Case Western University, and Northwestern University, with an emphasis on novel interaction for human-swarm teaming.

Another development, which would be as at home in the real-time strategy game series Starcraft as it is in a DARPA OFFSET exercise, is the operational management of swarm tactics from Carnegie Mellon University and Soar Technology. Their developments allowed the swarm to search and map a building on its own, and to automate resource allocation in the process of accomplishing tasks.

For now, the heart of the swarm is as a scouting organism built to provide information to human operators.

Watch it in action below:

In a project that can be classified as mostly biomimicry, with just a hint of necromancy, a team of researchers at Stanford University built a drone that flies on wings made of pigeon feathers. The goal, ultimately, is unlocking new science for morphing wings of aircraft.

It may also reveal a new kind of velcro-style fastener. Natural bird feathers, it turns out, can passively link and decouple to create the smooth surfaces needed to direct lift in flight.

While most of the implications in the study are about understanding the science of bird flight, the research was supported by funding from the Air Force Office of Scientific Research.

Building feathered military robots are likely not the ultimate end, but militaries have long expressed an interest in adapting birds to battle. (One of the more fascinating examples comes from World War I, where carrier pigeons were outfitted with cameras that took pictures at regular intervals.)

“Using a feathered biohybrid aerial robot,” the authors wrote, “we demonstrate how both passive mechanisms make morphing wings robust to turbulence.”

The velcro-like hooks on the feathers allow wings to lock into shape, depending on the direction moved, and also allow the wings to unlock when moved in other directions. This creates the same great flexibility seen in bird wing shape during flight.

Attaching the feathers to the skeletal wings of a drone allowed the researchers to explore the aerodynamics and properties of these feathers in outdoor flight and in wind tunnels. When the feathers were tested in flight unclumped and unlinked, they were unable to provide lift or stability. The passive interlinking mechanisms of the pigeon feathers, when allowed close enough contact to work, held together, making a functionally solid wing out of many disparate parts.

The researchers “hypothesize that directional fastening may not be as critical for some silent fliers because decaying atmospheric turbulence at night.”

One direction military designers and planners could explore is feathered drones for night flights, where lower turbulence and silent flying are at a premium. At present, owl-shaped drones are fixed wing, but in the future they might lean into research done today into flexible feathered wings.

Watch a video about the feathered wing drone below:

“We are ready to start our first lethality project next year in the joint war fighter targeting space,” said Department of Defense Chief Information Officer Dana Deasy said in December in an exclusive interview with sister brand Defense News.

This vision will be carried out by the Joint Artificial Intelligence Center, the military’s AI coordinating and developing organ. As for the specifics of how, exactly, it will bring the benefits of algorithmic processing to the fight, JAIC is still too early in the process to have much concrete information on offer.

The project will be part of a mission initiative under JAIC called Joint Warfighting.

While joint war fighting could in theory encompass every part of combat that involves more than one branch of the military, JAIC spokesperson Arlo Abrahamson clarified that the initiative encompasses, somewhat more narrowly, “Joint All-Domain Command and Control; autonomous ground reconnaissance and surveillance; accelerated sensor-to-shooter timelines; operations center workflows; and deliberate and dynamic targeting solutions.”

In other words, when the JAIC pairs AI with tools that aid in the use of force, it will come through either a communication tool, scout robots, battlefield targeting tools, workforce management software, or other targeting tools.

“The JAIC is participating in dialogue with a variety of commercial tech firms through industry days and other industry engagement activities to help accelerate the Joint Warfighting initiative,” said Abrahamson. “Contracting information for this mission initiative is under development.”

And while the JAIC is still figuring out if the first lethality project will be a robot, a sensor system, or logistics software, it is still explicitly interested in making sure that whatever the use of AI, it ultimately serves the interests of the humans relying on it in a fight.

As plainly as the JAIC can put it, the initiative is looking for “AI solutions that help manage information so humans can make decisions safely and quickly in battle,” said Abrahmson.

Humans, then, will still be the author of any lethal action. Those humans will just have some AI help.

Called the Variable Camber Compliant Wing, the new form features a “continuous skin” membrane, which can bend and warp to alter wing shape to the same effect as flaps in conventional aircraft. What is different is that the smooth, consistent plastic surface allows for quieter, more aerodynamic flight. It also, by reducing the need for distinct parts and harsh edges, is a lighter mechanism than a traditional flapped wing.

“Early estimates show [Variable Camber Compliant Wing] technology saving aircraft fuel consumption by 10 percent,” said Dr. James Joo, AFRL Advanced Structural Concepts team lead and VCCW program manager. “This was one of our main goals, and it fits the Air Force’s efforts to reduce overall energy costs.”

In 2018, Joo was awarded a patent for an early version of the wing, which allows “continuous wing reconfiguration that optimizes wing geometry for current altitude, airspeed, and lift-to-drag ratio requirements.”

The flight demonstrations took place in fall 2019, with an 8 ft. wing mounted on a commercial off-the-shelf drone. The promise is that such flapless wings could increase both fuel efficiency and control for long-range flights. If the wing continues to perform in tests, it could lead to a change in aircraft design, ushering in a whole unflappable era of flight.

Watch it in action below:

But new research into self-healing joints for legged robots could pave the way to a future of autonomous, self-repairing machines.

Legged robots have value for infantry because they allow machines to traverse inclines and rough terrain that’s ill-suited for wheels. In addition, legs can carry robots up ladders and over walls. Its one reason the United States has pursued multiple iterations of robot dogs for military use.

But if a leg breaks in the field, soldiers depending on that robot are left with a handful of unpleasant options.

If the unit has spare parts, they could halt and attempt an in-field repair. If the unit doesn’t the equipment, or doesn’t have time, they can abandon the robot in the hopes that friendly forces will recover it later. Or they can destroy the robot to prevent it from falling into enemy hands, losing not just the ability to carry supplies but spending finite resources wrecking it.

All of this is a knock against legged robots.

But new research, by the University of Tokyo’s JSK Lab and reported by IEEE Spectrum in December, used special joints, liquid metal and heat to let a robot break its leg and then heal.

The design solves two problems at once: by preparing a joint to break, the robot can protect its remaining joints in the fall, and by making the joint that breaks one that can “heal”, the robot is only out of commission for a short time.

“Healing” here is a sort of automated repair. Around the joint is a module of magnets and springs that is designed to separate and then come back together when the joint breaks. The joint is made of an alloy that melts at 122 degrees. The module holds the alloy in place and then melts with internal heaters. The whole process takes about 30 minutes, and leaves a leg weaker than before, but far more functional than if it had just remained broken.

For military planners and designers, the method of a self-healing joint enables robot design that can accompany humans without the risk of becoming a special burden. A little forgiveness in design and automated repair can go a long way to supporting imperfect navigation or climbing systems, especially as the robots are new and there is limited data on which they have been trained.

While the healing takes time, a squad in the field can take a short pause and focus on self-protection while the robot repairs itself. Even if the robot is no longer able to go forward, it could be sent autonomously back to base, essentially walking itself in for repair.

Long-term, automated self-repair is a feature worth exploring in any autonomous systems designed to operate far from humans. The more self-sufficient a robot can be, the more humans can trust it to perform tasks without direct supervision.

Watch below: