SEOUL, October 13 (AJP) - A soft robot modeled on a beetle can walk, pick up small objects and report back what it sees and how firmly it is gripping, while a person steers it by bending a finger.
Researchers at KAIST, the South Korean science and technology university, and the California Institute of Technology (Caltech), working with a team at Singapore's Nanyang Technological University, described the robot, called BeetleBot, in the journal Science Advances in August. KAIST announced the work on Tuesday. The robot is roughly the size of a real beetle, according to the paper.
Soft robots are built from flexible materials that bend and stretch instead of rigid metal, which lets them squeeze into places hard machines cannot. The parts that make them move, the parts that let them sense and the controls that guide them usually come as separate and often bulky hardware. That has made it hard to fit all three into a small body.
The team started with the insect itself. They studied how a beetle's leg muscles and joints move together and copied that layout in the robot's legs.
The artificial muscles are 3D-printed from a liquid crystal elastomer, a rubbery plastic that shrinks when heated. Small electric heaters warm each muscle on cue. By firing the muscles in different parts of each leg independently and in sequence, the researchers made the robot walk forward and turn.
At the front, a soft gripper copies the pincer-like jaws a beetle uses to seize food. When its artificial muscles contract, the gripper closes on an object. A pressure sensor inside registers the contact, because pressing on it narrows the gap between internal electrodes and changes its electrical signal.
The operator wears a stretchy sensor patch on one finger. Bending the finger stretches the patch and changes the electrical resistance of the carbon nanotubes inside, microscopic tubes of carbon that conduct electricity. The system reads those changes as one of four commands, walk forward, turn left, turn right or grab, and sends them to the robot over Bluetooth.
A small camera on the robot shows the operator what lies ahead, and the gripper's sensor reports whether it has made contact. The operator uses both to choose the next gesture. Commands travel out to the robot and sensor data travels back, a two-way loop the researchers describe as the core of the design.
In demonstrations, an operator guided BeetleBot around obstacles to a target object, which the robot gripped and carried away.
The researchers expect the design to lead to remote-controlled robots that can inspect narrow spaces people cannot reach and retrieve small objects from them. They said the combined muscle and sensor technology could also be adapted for soft grippers and medical and rehabilitation aids.
Kim Sang-ouk, a professor in KAIST's Department of Materials Science and Engineering, led the work with Caltech's Wei Gao as co-corresponding author. Kim said the study broadened the potential uses of soft robots by linking "the movement of artificial muscles, sensing and user control into a single system."
The first author, Kim In-ho, earned his doctorate at KAIST and built the robot while working as a postdoctoral researcher at Caltech. He is now an assistant professor of chemistry at Sungkyunkwan University.
"Going forward, we aim to increase the actuation speed and energy efficiency of the artificial muscles and advance control technology that uses sensory information, so that it can develop into a soft robot able to work in a variety of environments," he said.
KAIST said wider uses, such as environmental surveys and industrial equipment inspection, would also require changes to how the robot is powered and verification of its performance in real working environments.
[Reference Information]
Journal/Source: Science Advances
Title: BeetleBot: An integrated bioinspired soft robot for multimodal sensing and adaptive interaction
Link/DOI: 10.1126/sciadv.aeg8849
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