What if drones didn’t just fly and film but could also reach out, grasp things of different shapes and sizes, and perform useful work mid-air, like cleaning up disaster zones, repairing power lines, or even inspecting hard-to-reach bridge joints? 

That’s the kind of future envisioned by researchers at the University of Hong Kong (HKU). They have built a peculiar robotic drone arm inspired by the flexibility of an elephant’s trunk. Called the Aerial Elephant Trunk (AET), this soft and shape-shifting arm can twist, bend, and coil through tight spaces while hovering in the air.

Once equipped with this high-tech trunk, drones can tackle jobs that were once well beyond their reach.

For instance, “our system can adapt to various constrained environments, such as navigating through narrow holes, tubes, or crevices, and can handle a range of objects, including slender, deformable, irregular, or heavy items,” the study authors note.

AET versus traditional aerial robots 

Conventional aerial robots use rigid, jointed arms like those found on factory robots to perform tasks. These arms are heavy, stiff, and usually come with claw-like grippers. The problem with such solutions is that they reduce flight time, struggle to navigate tight spaces, and can only grasp specific object shapes. 

For aerial tasks in cluttered environments such as collapsed buildings, pipelines, or dense forests, these robots quickly hit a wall, literally and figuratively. To overcome these limits, the HKU team developed a completely different kind of aerial manipulator, a lightweight continuum arm made of soft materials that mimics the movement of an elephant trunk.

Unlike a typical robotic arm that uses rigid joints and fingers, the AET uses a soft, flexible structure that scientists call a continuum manipulator. This lets the drone’s arm bend, twist, and curl into just about any shape. This means it doesn’t need to rely on traditional grippers or claws to pick things up. Instead, it wraps its arm around an object, so no matter how irregular the shape is, it holds on.

However, building such a system wasn’t easy. For years, scientists have struggled to balance two competing needs in aerial robotics: payload capacity (how much weight a drone can carry) and dexterity (how precise or flexible its movements are). For example, if you add a big, strong robotic arm to a drone, it usually becomes too heavy to fly well. If you make the arm light and flexible, it often can’t handle complex tasks or carry enough weight.

The researchers addressed this challenge by developing a compact, lightweight (weighing only 1.8 kg), and highly flexible arm that can be directly mounted on a drone. Made from soft materials, the arm is safer to operate near people and delicate structures. 

Also, because it doesn’t depend on rigid joints, it can weave through tight pipes, curve around obstacles, and carry out tasks in spaces where conventional drones and aerial robots simply can’t go.

“AET is extremely dexterous compared to existing aerial manipulators, as its body can change into any shape. It can grasp objects of various sizes and shapes using its body, a capability that is almost impossible for conventional aerial manipulators, which can only grasp objects using grippers,” Peng Lu, one of the study authors and a professor at HKU, said.

Drones will have the superpower to do anything

The AET isn’t just a cool gadget, it could redefine what drones can do. Picture a fleet of AET-equipped drones cleaning up after natural disasters, removing fallen branches from high-voltage cables, or inspecting the undersides of bridges and wind turbines. These kinds of jobs are not only risky for humans but often impossible for today’s drones with rigid arms and limited flexibility. 

Moreover, the study authors suggest that their robot arm can help unlock what experts are calling the low-altitude economy, an emerging industry built around drones and other flying robots that operate at low altitudes (typically below 1000 meters) close to where people live and work. 

It includes applications like aerial deliveries, agricultural monitoring, environmental surveys, and various other tasks. As these technologies become more advanced and reliable, they’re expected to play a big role in everyday services and create entirely new kinds of jobs and businesses in urban and rural areas.

The researchers now plan to improve the arm’s sensitivity and control so it can handle even more complex tasks in unpredictable environments. They’re also looking into how fleets of AET-equipped drones could work together, opening the door to even larger and more ambitious missions. 

The study is published in the journal Nature Communications.