A robot that grows

Worm-like Soft-Bot overcomes even complex obstacles through growth

The robotic worm does not glide but grows - overcoming all obstacles. © JD Greer
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Whimsical construct: US researchers have designed the first robot that can grow. Similar to a plant shoot, its tip is getting longer and longer. The pneumatically powered robot can easily negotiate narrow, twisting aisles and chasms and even grow smooth walls, as proven by prototype tests. Applications for such reconnaissance robots would be ample, as the scientists explain.

Most robots are rather inflexible constructs of metal and other stiff materials. But there are exceptions: an X-shaped soft robot can overcome the overflow thanks to thick silicone pads, the "Oktobot" moves hydraulically away and does not require any hard components, and a robotic ray even combines a polymer body with living muscle cells.

Growth from the top

Elliot Hawkes of Stanford University and his team are going one step further. They have designed a soft robot that not only flexibly changes shape, but can even grow: similar to the shoot of a vine or a mushroom thread, it can last longer and easily negotiate curves or narrow passages.

"The robot body extends from the end without the rest of the body moving, " explains Hawkes. "This allows the body to stick to the ground or be trapped between stones without the robot being disturbed: its tip continues to move as new material is replenished at the end."

The working principle of the robot worm. Compressed air gradually expands the wrapping material at the top. © Hawkes et al., Sci. Robot. 2, eaan3028 (2017)

pneumatic drive

This is made possible by the special construction of the robot. It consists of a thin shell of plastic material, which is initially folded in a small space in itself. Should he move, his control program activates a pump, which gradually everts the shell forward. "The driving force is the pressure, " explains Hawkes. display

An integrated camera and sensors allow the robot worm to grow its tip purposefully in the direction in which it wants or in which the way is free. The deciding factor here is that the robot as a whole does not glide, but simply grows with its tip to where it should go. "Because it does not slide, the robot can thus overcome even tight, narrow passages, " says Hawkes.

From the crate tractor to the cave explorer

How versatile the novel robot can be used, the researchers demonstrate with first prototypes: In one experiment, the robot worm grew through the narrow gap under a door through, in another he raised a 100-pound box. He wound easily through a narrow labyrinth and even dragged along a cable that he laid in this way. Even free-spinning, the robot can grow taller.

In an obstacle course the robot crawled over sticky fly paper, over pointed nails and even an ice wall, in order to successfully deposit a sensor at the target. Even damage to its case does not stop the robot worm: The holes caused by pointed nails lead to low pressure loss because the nails simply get stuck and thus the L Selbstcher self-sealed.

The robot worm can overcome a variety of obstacles and even grow freely in the air. Stanford University

Many applications

The benefit of such a robot worm is obvious: it could, for example, provide sensor data and camera images from the wreckage during disaster operations. "Applications are everywhere where a robot has to move through rough, unknown terrain and the conditions are unpredictable, " explains co-author Laura Blumenschein. "He does not have to worry about being trapped or damaged while exploring."

In the meantime, the growing robot could be anywhere where flexibility and low weight are needed. Even in direct contact with humans, this robot could act without becoming a risk of injury to its human partner.

Different sizes and drive types

Another advantage: Such robots can be produced in different sizes. The researchers have already designed versions from less than two millimeters in length to more than 70 meters long "heat". Next, they want to develop variants that work with hydraulic fluid instead of air. In addition, they work on particularly tear-resistant shell materials such as nylon and kevlar. (Science Robotics, 2017; doi: 10.1126 / scirobotics.aan3028)

(Stanford University / University of California, 24.07.2017 - NPO)