Technology

MIT researchers create X-ray vision headset

The device, known as X-AR, is designed to help people locate specific items in small environments.

By Ross Cristantiello

March 1, 2023

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Researchers at MIT have developed a headset that lets people track and find items hidden from view, effectively giving them X-ray vision. 

Through the use of techniques called computer vision and wireless perception, the headset automatically locates specific items that are not in the wearer’s line of sight. It then guides the users toward the items, according to MIT. The system relies on radio frequency signals that can pass through everyday materials like cardboard, plastic, and wood. 

The items being searched for must be labeled with Radio Frequency Identification (RFID) tags that reflect signals sent by an antenna. 

Dubbed X-AR, the headset guides wearers through an augmented reality interface. The items being searched for are shown as transparent spheres to the users. Once they are found, X-AR verifies that the wearer has picked up the correct object. 

 “Our whole goal with this project was to build an augmented reality system that allows you to see things that are invisible — things that are in boxes or around corners — and in doing so, it can guide you toward them and truly allow you to see the physical world in ways that were not possible before,” MIT professor Fadel Adib said in a statement. 

Researchers tested the device in a mock warehouse environment. They found that it could localize hidden items to within 9.8 centimeters, on average. It verified that users picked up the correct item with a 96 percent accuracy, according to MIT. 

Those behind the project envision it as a useful tool for e-commerce warehouse workers. It would help them quickly find things amid many cluttered shelves and boxes. Researchers also say that X-AR could be used in a manufacturing facility so that workers can find the correct parts as they assemble products. 

Developing the headset

Researchers had to make an existing AR headset work with an antenna that could communicate with RFID tags. The majority of RFID localization systems utilize numerous antennas spaced out by meters. The team at MIT had to develop a lightweight antenna that could reach the bandwidth necessary to communicate with the RFID tags. 

“One big challenge was designing an antenna that would fit on the headset without covering any of the cameras or obstructing its operations. This matters a lot, since we need to use all the specs on the visor,” Aline Eid, a former postdoctoral researcher who now works as an assistant professor at the University of Michigan, said in a statement.

To do this, they boosted the bandwidth of a simple loop antenna by tapering its width and adding gaps, according to MIT. They then optimized it to work while attached to the headset. 

The next step was figuring out how to use the antenna to find RFID-tagged items. They relied on a specific method known as synthetic aperture radar, which is commonly used by airplanes to find objects on the ground. The headset takes various measurements from different vantage points as a user walks around a room. The measurements are then combined, and work in conjunction with visual data from the headset’s self-tracking system to build a map of the room and determine where the headset is in relation to the environment around it. 

The X-AR device calculates the probability of the RFID tag at each location as the user walks, and the probability will be the highest at the tag’s exact location. 

Throughout the course of their work, researchers found that the technology needed for X-ray vision synergized well with natural human behavior. 

“While it presented a challenge when we were designing the system, we found in our experiments that it actually works well with natural human motion. Because humans move around a lot, it allows us to take measurements from lots of different locations and accurately localize an item,” Laura Dodds, a co-author of the paper on X-AR, said in a statement. 

Once the item is picked up, X-AR checks that the RFID tag is sending the correct signals associated with the item to verify that the user found what they were looking for. 

When first putting on the headset, users are greeted with simple menus that allow them to select an object from a database of tagged items. Once the item is located, the headset tells users where to walk in the form of footsteps on the floor. 

“We abstracted away all the technical aspects so we can provide a seamless, clear experience for the user, which would be especially important if someone were to put this on in a warehouse environment or in a smart home,” co-author Maisy Lam said in a statement. 

Future X-ray improvements

The future of X-ray vision could be bright. While the X-AR headset works fine at the moment, MIT researchers are still working to refine the device. They plan to investigate whether its visualization and interaction features could be enhanced by using other ways of sensing, like WiFi. They are also toying with the possibility of extending the range of the headset’s antenna, which currently only works at a range of 3 meters. 

Adib said that, while the initial work on this project is promising, the potential for improvement is immense. 

“Because there isn’t anything like this today, we had to figure out how to build a completely new type of system from beginning to end,” Adib said in a statement. “In reality, what we’ve come up with is a framework. There are many technical contributions, but it is also a blueprint for how you would design an AR headset with X-ray vision in the future.”