Rise of the ChemBots
Article originally from American Chemistry magazine.
Recently, the Defense Advanced Research Projects Agency (DARPA)—the research agency for the Department of Defense where the precursor to the Internet was first developed—solicited proposals to develop new Chemical Robots (ChemBots), using soft and flexible materials to enable machines to change their size and shape to squeeze through gaps smaller than their own normal dimensions. While the concept may sound unusual at first, shape-shifting mobile machines have very real military purposes.
“The ability to safely and covertly gain access to denied or hostile areas and perform useful tasks provides critical advantages over a broad spectrum of military operations,” reads DARPA’s solicitation. “An effective and logistically attractive means for gaining entry is to deploy an unmanned platform, such as a robot. However, the only available points of entry are small openings in buildings, walls, under doors, etc.”
DARPA suggests a robot built for such purposes would need to be soft enough to squeeze through these gaps, but large enough to carry important equipment. “Current robotic platforms are constructed primarily of hard materials and, while capable of locomotion with embedded payloads, cannot change their physical dimensions,” the solicitation says.
Based on nature
In some respects, the idea is to imitate nature. Different types of ‘soft’ animals—including some mice, insects, and octopuses—squeeze nimbly through tiny gaps. They use a variety of natural ‘reversible mechanisms,’ including elastic tissues, flexible musculoskeletal structures, and body parts that can be changed from stiff to flexible and vice versa. Another factor is locomotion itself. Soft invertebrates employ various means to grip and crawl along surfaces. Earthworms and caterpillars use peristalsis, involving wavelike muscular movements; snails and slugs perform pedal waves; and many tinier organisms use cilial motions, vibrating their eyelash-like structures.
Steps to success
DARPA is asking robotics experts for innovative proposals to combine their own expertise with that of soft materials chemistry. Specifically, a ChemBot must be able to perform the following steps:
1. Travel some distance.
2. Pass through an opening that is arbitrarily shaped and much smaller than the robot’s own largest dimension.
3. Reconstitute its original shape, size, and functionality on the other side.
4. Travel another distance.
5. Perform a function involving its embedded payload.
Achieving these results will require new technological breakthroughs, including materials, systems, and/or architectures that can not only move, but also ‘morph’ in three dimensions.
Pre-ChemBots
Scientists have already developed robots with some of the specified characteristics.
SuperBot
At the University of Southern California (USC), researchers have created SuperBot, a set of cube-shaped modular units that can communicate with and attach to each other to form larger robots. While currently intended for space exploration, the technology lends itself to applications in other dangerous locales, including military scenarios.
“The idea is to accommodate different tasks in different environments,” SuperBot Developer Wei-Min Shen told CNN. Shen is Director of USC’s Polymorphic Robotics Laboratory and Associate Director of its Center for Robotics and Embedded Systems. Already, SuperBot can be commanded to form certain configurations, such as a ‘snake’ to crawl through a pipe or ‘legs’ to climb an incline. Shen’s next goal is to enable SuperBot to make such decisions by itself. “We’d like it to see a narrow gap and say, ‘Okay, my body is too big,’ and change to go through it,” he told CNN. “And if the terrain is downhill, it could become a ball and roll down.” Another feature Shen suggests could be added is the capability to swim.
WSL
Meanwhile, at Virginia Polytechnic Institute and State University (Virginia Tech), research has focused on the Whole Skin Locomotion (WSL) mechanism, a propulsion system designed to allow robots to move through gaps that are smaller than their usual dimensions, using their own ‘skin’ to do so.
Dennis Hong, Assistant Professor of the Mechanical Engineering Department and Director of the Robotics & Mechanisms Laboratory says WSL was inspired by singlecell organisms—specifically, the pseudopod (cytoplasmic foot) of the amoeba. His WSL robot, currently in the prototype stage, is an elongated cylindrical arrangement of contracting and expanding actuating rings. The technology has many potential applications, ranging from the medical field—performing endoscopic surgery—to search-and-rescue efforts in rubble and other difficult areas.
