Industrial Electronics

Video: Swimming soft robot uses light for control and power

11 September 2019

A new soft robot has been designed by the UCLA Samueli School of Engineering that uses constant light for both power and steering.

The soft robot, called OsciBot, moves by oscillating its tail and the design was inspired by the movement of animals such as jellyfish and moths that are attracted to light or move away from it.

The soft robot can be directly powered by constant light, rather than relying on light energy that has been harvested and stored in the battery. The robot is made of soft hydrogel that swells when placed in water and responds to light. As a result, it does not require batteries or need to be tethered to another power source.

To create the soft robot, researchers built a 2 cm long flexible cylinder and anchored it to the bottom of a water tank. Then, they directed a beam of light at the cylinder and found the light made it bend as fast as 66 times per minute — moving the position of the light source allowed the robot to bend both left and right and up and down.

The speed at which the soft robot oscillates can be adjusted based on the cylinder’s length and thickness as well as how much light is used. Researchers then used the same hydrogel to build a robot shaped like a rectangular surfboard. When light hits a spot on the tail, it heats up and causes the robot to eject some of its water and shrink in volume. Then the tail creates a shadow that cools the section where the laser made contact with the robot, causing the tail to descend again.

The process repeats as long as the target spot is hit. Researchers observed the tail flapping 35 times per minute during testing, fast enough to move the robot 1.15 times its body length per minute.

“Typically, generating oscillation relies on intermittent energy input, such as pulsed light or alternating electric current,” said Ximin He, a UCLA assistant professor of materials science and engineering, and the study’s principal investigator. “By contrast, this study shows a new way of generating oscillation, by using a constant energy input that is easily accessible from the ambient environment and inexpensive to harness.”

Researchers have been experimenting with different types of soft robots for the past few years including those patterned after snakes, a fish, an eel, a worm, 3D printed origami and more.

The full research can be found in the journal Science Robotics.

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