MIT developed a robotic finger able to sense buried items

Researchers at MIT have developed a new slender robotic finger designed to sense buried items. The tech uses tactile sensing to identify objects underground, and researchers believe it could one day be used to help disarm landmines and inspect buried cables. Researchers say identifying buried items in granular material like sand is very difficult.

Identifying objects in granular material with a robot requires fingers slender enough to penetrate the sand, mobile enough to wiggle out of the material it's searching, and sensitive enough to feel the detailed shape of the buried object. The sharp-tipped robotic finger MIT developed is fitted with tactile sensing allowing it to identify buried objects, and is called Digger Finger.

In testing, Digger Finger can dig through granular material such as sand or rice and correctly sense the shape of objects buried inside the material. Attempting to identify objects buried inside a granular material like sand, gravel, and other types of loosely packed particles isn't a new challenge. Researchers have used technology such as ground penetrating radar or ultrasonic vibrations to sense objects buried underneath granular material in the past.

Those techniques provide a hazy view of submerged objects, making it challenging to differentiate materials, such as telling the difference between rock and bone. The team had to design the robotic finger to be slender and sharp-tipped. In previous work, the team had used a sensor made of a clear gel covered with a reflective membrane that could deform when objects were pressed against it called GelSight. Behind the membrane were different colors of LED lights and a camera.

The light shines through the gel and onto the membrane while the camera collected the membrane pattern of reflection. Computer vision algorithms are then extracted through the shape of the contact area where the soft finger touches the object. The device was very good at artificial touch but was very bulky. The GelSight sensor was modified in the latest research changing its shape to a slender cylinder with a beveled tip.

They then removed two-thirds of the LED lights relying on a combination of blue LEDs and colored fluorescent paint to save complexity and space. The result was the highly functional and capable Digger Finger sensor. Currently, the researchers are exploring new motions to optimize the Digger Finger's ability to navigate various media.