Ghost Robotics’ Arm Brings Manipulation to Military Quadrupeds

Ghost Robotics is today announcing a major upgrade for their Vision 60 quadruped: an arm. Ghost, a company which originated at the GRASP Lab at the University of Pennsylvania, specializes in exceptionally rugged quadrupeds, and while many of its customers use its robots for public safety and disaster relief, it also provides robots to the United States military, which has very specific needs when it comes to keeping humans out of danger.

In that context, it’s not unreasonable to assume that Ghost’s robots may sometimes be used to carry weapons, and despite the proliferation of robots in many roles in the Ukraine war, the idea of a legged robot carrying a weapon is not a comfortable one for many people. IEEE Spectrum spoke with Ghost co-founder and current CEO Gavin Kenneally to learn more about the new arm, and to get his perspective on selling robots to the military.

The Vision 60’s new arm has six degrees of freedom. Ghost Robotics

Robots for the Military

Ghost Robotics initially made a name for itself with its very impressive early work with the Minitaur direct-drive quadruped in 2016. The company also made headlines in late 2021, when a now-deleted post on Twitter (now X) went viral because it included a photograph of one of Ghost’s Vision 60 quadrupeds with a rifle mounted on its back.

That picture resulted in a very strong reaction, although as IEEE Spectrum reported at the time, robots with guns affixed to them wasn’t new: To mention one early example, the U.S. military had already deployed weapons on mobile robots in Iraq in 2007. And while several legged robot companies pledged in 2022 not to weaponize their general purpose robots, the Chinese military in 2024 displayed quadrupeds from Unitree equipped with guns. (Unitree, based in China, was one of the signers of the 2022 pledge.)

The issue of weaponized robots goes far beyond Ghost Robotics, and far beyond robots with legs. We’ve covered both the practical and ethical perspectives on this extensively at IEEE Spectrum, and the intensity of the debates show that there is no easy answer. But to summarize one important point made by some ethicists, some military experts, and Ghost Robotics itself: robots are replaceable, humans are not. “Customers use our robots to keep people out of harm’s way,” Ghost CEO Kenneally tells Spectrum.

It’s also worth pointing out that even the companies who signed the pledge not to weaponize their general purpose robots acknowledge that military robots exist, and are accepting of that, provided that such robots are used under existing legal doctrines and operate within those safeguards—and that what constraints should or should not be imposed on these kinds of robots is best decided by policymakers rather than industry.

This is essentially Ghost Robotics’ position as well, says Kenneally. “We sell our robots to U.S. and allied governments, and as part of that, the robots are used in defense applications where they will sometimes be weaponized. What’s most critical to us is that the decisions about how to use these robots are happening systematically and ethically at the government policy level.”

To some extent, these decisions are already being made within the U.S. government. Department of Defense Directive 3000.09, ‘Autonomy in Weapon Systems,’ lays out the responsibilities and limitations for how autonomous or human-directed robotics weapons systems should be developed and deployed, including requirements for human use-of-force judgements. At least in the U.S., this directive implies that there are rules and accountability for robotic weapons.

Vision 60’s Versatile Arm Capabilities

Ghost sees its Vision 60 quadruped as a system that its trusted customers can use as they see fit, and the manipulator enables many additional capabilities. “The primary purpose of the robot has been as a sensor platform,” Kenneally says, “but sometimes there are doors in the way, or objects that need to be moved, or you might want the robot to take a sample. So the ability to do all of that mobile manipulation has been hugely valuable for our customers.”

As it turns out, arms are good for more than manipulation. “One thing that’s been very interesting is that our customers have been using the arm as a sensor boom, which is something that we hadn’t anticipated,” says Kenneally. Ghost’s robot has plenty of cameras, but they’re mostly at the viewpoint of a moderately-sized dog. The new arm offers a more human-like vantage and a way to peek around corners or over things without exposing the whole robot.

Ghost was not particularly interested in building their own arm, and tried off-the-shelf options to get the manipulation bit working. And they did get the manipulation working; what didn’t work were any of those arms after the 50 kilogram robot rolled over on them. “We wanted to make sure that we could build an arm that could stand up to the same intense rigors of our customers’ operations that the rest of the robot can,” says Kenneally. “Morphologically, we actually consider the arm to be a fifth leg, so that the robot operates as a unified system for whole-body control.”

The rest of the robot is exceptionally rugged, which is what makes it appealing to customers with unique needs, like special forces teams. Enough battery life for more than three hours of walking (or more than 20 hours on standby) isn’t bad, and the Vision 60 is sealed against sand and dust, and can survive complete submergence in shallow water. It can operate in extreme temperatures ranging from -40 °C to 55 °C, which has been a particular challenge for robots. And if you do manage to put it in a situation where it physically breaks one of its legs, it’s easy to swap in a spare in just a few minutes, even out in the field.

The Vision 60 can open doors withe high-level direction from a human operator.Ghost Robotics

Quadruped Robot Competition From China

Despite Ghost quietly selling over a thousand quadrupeds to date, Kenneally is cautious about the near future for legged robots, as is anyone who has seriously considered buying one, because it’s impossible to ignore the option of just buying one from a Chinese company at about a tenth the cost of a quadruped from a company based in the U.S. or Europe.

“China has identified legged robotics as a lynchpin technology that they are strategically funding,” Kenneally says. “I think it’s an extremely serious threat in the long term, and we have to take these competitors very seriously despite their current shortcomings.” There is a technological moat, for now, but if the market for legged robots follows the same trajectory as the market for drones did, that moat will shrink drastically over the next few years.

The United States is poised to ban consumer drone sales from Chinese manufacturer DJI, and banned DJI drone use by federal agencies in 2017. But it may be too late in some sense, as DJI’s global market share is something like 90 percent. Meanwhile, Unitree may have already cornered somewhere around 70 percent of the global market for quadrupeds, despite the recent publication of exploits that allow the robots to send unauthorized data to China.

In the United States in particular, private sector robotics funding is unpredictable at the best of times, and Kenneally argues that to compete with Chinese-subsidized robot-makers American companies like Ghost who produce these robots domestically will need sustained U.S. government support, too. That doesn’t mean the government has to pick which companies will be the winners, but that it should find a way to support the U.S. robotics industry as a whole, if it still wants to have a meaningful one. “The quadruped industry isn’t a science project anymore,” says Kenneally. “It’s matured, and quadruped robots are going to become extremely important in both commercial and government applications. But it’s only through continued innovation that we’ll be able to stay ahead.”