EleTac: elephant-inspired soft robotic gripper with a delicate sense of touch

Inspiration from an elephant's trunk helped create a soft robotic gripper with a subtle touch. The device is capable of not only carefully grasping objects, but also feeling them.

Soft grip with pneumatics

The soft pneumatic gripper closes under air pressure. This allows you to grasp objects gently and universally. Thanks to the visual sensor, it can detect both contact with external objects and its own shape. Photo: Professor Wang An Ho, Japan Institute of Advanced Science and Technology, Japan.

Soft grippers made of flexible materials are attracting more and more attention from roboticists. Unlike conventional robots made of hard metal or plastic, such grippers take objects more accurately and themselves adapt to different shapes.

This makes them ideal for delicate tasks such as working with fruit, baked goods, laboratory samples and medical supplies.

The problem of touch for flexible robots

But grabbing objects is only part of what robots can do. To manipulate objects with human dexterity, they need the sense of touch. Feedback includes: where the contact occurs, how hard the object is pressed, what its shape is, and even how the gripper’s own “fingers” are positioned.

The main difficulty is that the very flexibility that makes soft grippers useful makes it difficult to equip them with sensors. The material constantly bends and stretches - conventional sensors are difficult to embed without limiting mobility or covering only small areas. But what if you spy on one of nature's most impressive grasping mechanisms?

Inspiration from nature

In a recent study published in IEEE Transactions on Robotics, a team led by Professor Wang Anh Ho from the Japan Institute of Advanced Science and Technology (JAIST) developed EleTac. This is a soft robotic gripper inspired by the tip of an elephant's trunk.

The paper describes an innovative design that combines object grasping with high-precision tactile perception and proprioception - the robot's ability to sense the position and movement of its own body. The team also included Associate Professor Shan Luo and PhD student Xuyang Zhang from King's College London (UK), Dr Tuan Thai Nguyen from JAIST and Dr Quan Khanh Lu from Purdue University (USA).

How does EleTac work?

EleTac uses a pair of soft pneumatic fingers that gently close around objects. Instead of building multiple sensors into the gripper, the researchers equipped it with a single internal fisheye camera. She observes from the inside how the soft material is deformed when grabbed. Using the resulting images, the team trained several deep learning algorithms to extract different types of tactile information.

Soft grip handles fragile items safely. Its sensor capabilities are useful, for example, for automatic dishwashing or research in low visibility conditions. Photo: Professor Wang An Ho, Japan Institute of Advanced Science and Technology, Japan.

Experiments and results

The team evaluated EleTac in a series of capture and sensing experiments. Using a simple control strategy, the gripper successfully handled a variety of objects: fruit, tofu, fabric, tools, bolts, and even playing cards.

In addition, EleTac was tested in two particularly challenging scenarios:

Find and pull out the handle buried in the sand by touch.

Wipe the marker off the curved dish with a sponge.

The second task required the gripper to adjust its movements depending on how tightly the sponge was pressed against each surface.

Practical benefits

Researchers consider one of the main practical advantages of EleTac to be its compactness, lightness and low cost. “EleTac, fully covered in vision-based haptic skin, is suitable as a turnkey end effector for existing robotic platforms and humanoid robots. For example, gripping holds promise for delicate operations,” says Ho.

Beyond immediate commercial and industrial applications, EleTac is a step toward the widespread adoption of service robots.

“Able to sense contact and apply gentle forces, soft robots will be able to assist with daily activities, support elderly or vulnerable people, and perform operations that today's hard systems cannot. In the near future, we see safer and more skilled robots working side by side with people in homes, hospitals and public places,” Ho concluded.