With stretchy fingers, Baxter the robot gets a grip

A Baxter robot is outfitted with soft fingers that can feel the shape of the object its picking up.
A Baxter robot is outfitted with soft fingers that can feel the shape of the object its picking up.

The thing that drives robot makers batty is this: Perfectly natural human gestures are maddeningly hard to mimic in a machine.

Picking up a mug, for example, but also holding it the right way. You know, so the coffee doesn’t wind up on the floor. Climbing a flight of stairs without tripping over your ankles. Opening a door.

A new project from the MIT robotics lab led by CSAIL director Daniela Rus is taking a shot at solving the gripping problem. This team built stretchy and bendable fingers for a Baxter robot that can wrap themselves around a variety of objects.

Bianca Homberg, a graduate student at MIT designed flexible grippers that can wrap around a variety of shapes.

This is a smart design for a few different reasons. If a robot has rigid, metal fingers, each needs to be given very specific instructions about how to grab an object: how narrow the grasp needs to be so that it can grip that very specific shape. Change the object? The robot demands a new set of instructions.

The tentacle-style gripper design, which can expand to accommodate a shape, and grasps radially – surrounding an object instead of picking it up with pincers – means the robot can use the same How To sheet to pick up a tennis ball but also an egg. It can be gentle with both.

These fingers are similar to grippers that Cambridge startup Soft Robotics is designing. This approach won the two-year-old startup a contract to begin sorting fresh cut fruit and vegetables.

But the Rus lab’s grippers have one additional feature: sensors. Electrodes on the stretchy fingers send back tactile information to the Baxter system. So when it picks up an object, it can make a rough guess as to what it is.


“The tricky thing is because it’s so flexible, you don’t know where your fingers wound up,” said Bianca Homberg, a graduate student who led the work at Rus’s lab. The goal is to have the robot to pick up an object, but also interact with it.

The Rus lab has been steadily pushing the abilities of soft robots. For example, last year, another graduate student demonstrated a snake-like soft robot that can wind its way through narrow spaces.

Homberg will be presenting her work on the flexible fingers at the International Conference on Intelligent Robots and Systems conference in Hamburg, Germany, this week.

Before joining the Rus lab at MIT, Homberg did internships at SpaceX and Google Engineering. In February, Homberg will move to San Francisco to join Google Robotics.

Nidhi Subbaraman writes about science and research. Email her at [email protected]
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