The global site of the UK's leading magazine for automation, motion engineering and power transmission
18 June, 2024

Twitter link

Soft robotic gripper can lift items 100 times its weight

15 March, 2019

Researchers in the US have developed a robotic gripper that’s soft and strong. The cone-shaped structure, called Magic Ball, collapses in on objects and can pick up items that are 100 times its weight. The gripper can grasp objects ranging from soup cans and wine glasses, to single florets of broccoli.

“One of my moonshots is to create a robot that can automatically pack groceries for you,” says professor Daniela Rus, director of MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL), which has developed the gripper in conjunction with Harvard’s School of Engineering and Wyss Institute for Biologically Inspired Engineering.

“Previous approaches to the packing problem could only handle very limited classes of objects – objects that are very light or that conform to shapes such as boxes and cylinders – but with the Magic Ball gripper system, we’ve shown that we can do pick-and-place tasks for a large variety of items ranging from wine bottles to broccoli, grapes and eggs,” Rus explains. “In other words, objects that are heavy and objects that are light. Objects that are delicate, or sturdy, or that have regular or free-form shapes.”

The hollow, vacuum-powered gripper surrounds an object to pick it up. It has three parts: an origami-based skeleton; an airtight skin to encase the structure; and a connector. The team created it using a mechanical rubber mould and a special heat-shrinking plastic that folds itself at high temperatures.

The skeleton is covered either by a rubber balloon or a thin sheet of fabric. When testing the gripper with a robot, the developers found it could grasp and lift objects up to 70% of its diameter, and could pick up and hold soft foods without damaging them. It could also pick up bottles weighing 1.8kg.

“Companies like Amazon and JD want to be able to pick up a wider array of delicate or irregular-shaped objects, but can’t with finger-based and suction-cup grippers,” says Shuguang Li, a post-doctoral student at MIT CSAIL and Harvard’s John A. Paulson School of Engineering and Applied Sciences. “Suction-cups can’t pick up anything with holes – and they’d need something much stronger than a soft-finger-based gripper.”

The new gripper currently works best with cylindrical shapes such as bottles or cans. Its shape makes it more difficult to grasp flat objects such as books.

The soft robotic gripper can pick up delicate items weighing much more than itself

“One of the key features of this approach to manipulator construction is its simplicity,” says Robert Wood, a professor at Harvard’s School of Engineering and Wyss Institute for Biologically Inspired Engineering. “The materials and fabrication strategies used allow us to rapidly prototype new grippers, customised to object or environment as needed.” 

In the future, the team hopes to add computer vision that would allow the gripper to “see” and to grasp specific parts of objects from any angle or orientation.

Conventional rigid grippers tend to work best in structured environments with predefined shapes and locations, and typically can’t cope with uncertainties in placement or form. In recent years, roboticists have been tackling this problem by making grippers out of soft, flexible materials, such as rubber. This pliability lets them pick up a variety of objects, but they usually cannot handle large or heavy items.

Soft robotic fingers powered by compressed air are usually not strong enough to pick up heavy objects. Novel gripper designs such as ball-shaped grippers can handle a wider range of objects than fingers, but are limited in the angles at which they can operate.

  • To view a digital copy of the latest issue of Drives & Controls, click here.

    To visit the digital library of past issues, click here

    To subscribe to the magazine, click here



"Do you think that robots create or destroy jobs?"



Most Read Articles