Researchers testing out the prototype version. Jeff Fitlow/Rice University
Soon, a flexible octopus-like robot could be completely free of wires or internal electronics.
Engineers at Rice University have unveiled a new soft robotic arm controlled by laser beams.
Interestingly, this soft robotic arm can handle surprisingly complex tasks, from navigating around obstacles to hitting a ball precisely.
“This was the first demonstration of real-time, reconfigurable, automated control over a light-responsive material for a soft robotic arm,” said Elizabeth Blackert, a Rice doctoral alumna and first author.
The team says this development could benefit various fields, from implantable surgical devices to industrial machines.
The magic behind this arm’s movement lies in a light-responsive material called azobenzene liquid crystal elastomer. Credit: Jeff Fitlow/Rice University
Light-responsive material
There has been a major advancement in developing soft robotic arms in the past few years. For example, China recently unveiled an octopus-inspired robotic arm capable of supporting loads up to 260 times its weight.
However, the current standard robots rely on fixed joints, which limit the range of motion.
“A major challenge in using soft materials for robots is they are either tethered or have very simple, predetermined functionality,” said Hanyu Zhu, assistant professor of materials science and nanoengineering.
“Building remotely and arbitrarily programmable soft robots requires a unique blend of expertise involving materials development, optical system design, and machine learning capabilities,” added Zhu.
The magic behind this arm’s movement lies in a light-responsive material called azobenzene liquid crystal elastomer.
This unique polymer reacts to light by shrinking under blue laser light and then quickly relaxing and regrowing in the dark. A swift response is key for real-time control.
“When we shine a laser on one side of the material, the shrinking causes the material to bend in that direction. Our material bends toward laser light like a flower stem does toward sunlight,” added Blackert.
Use of machine learning
The researchers explained the science behind the movement.
A spatial light modulator, a specialized device, divides a single laser beam into numerous “beamlets.” Each beamlet offers versatile control: it can be aimed at different parts of the arm, its intensity can be fine-tuned, and it can be toggled on or off.
The team says the arm can flex or contract at any desired location, similar to the fluid movements of an octopus’s tentacles.
But how does a robot controlled by light perform complex tasks like navigating an obstacle or hitting a ball? That’s where machine learning comes in.
The team developed a convolutional neural network, a type of artificial intelligence used in image recognition. It was trained by showing various light patterns and the resulting arm movements.
The current prototype is flat and moves in two dimensions. The researchers envision three-dimensional versions, potentially equipped with additional sensors and cameras.
“This is a step towards having safer, more capable robotics for various applications ranging from implantable biomedical devices to industrial robots that handle soft goods,” Blackert said.
Theoretically, this technique could produce a robot with virtually limitless degrees of freedom, greatly exceeding what traditional robots with rigid joints can achieve.
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The findings were published in Advanced Intelligent Systems.
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