Imagine you are at the movies and you see a Roomba-like robot climbing a wall or clinging to a ceiling. How would that work? If you are like us, you might think of suction cups or something mechanical or magnetic in the wall. Then again, it is a movie, so maybe it is just a camera trick. The robots from the Bioinsipired Robotics and Design Lab at UCSD are no camera trick, though. As [Evan Ackerman] mentions in a post on IEEE Spectrum, “It’s either some obscure fluid effect or black magic.” You can watch a video about the bots, below.
It turns out, the answer is closer to a suction cup than you might think. According to the paper from the lab, a small flexible disk vibrates at 200 Hz. This generates a thin (less than 1 mm) layer of low pressure air in between the disk and the underlying surface. The robot can resist a force of up to 5 newtons from the suction from the disk.
The disk is only 14 cm in diameter, so somewhere around the size of a common saucer. This seems like something that would be simple to replicate with your own robots. The biggest problem is noise. At 200 Hz, you will hear this robot coming. It also looks like scaling up or down could be a problem. Too small, and the motor that drives the eccentric weight eats up too much space. Larger, you have more to support. We wondered if a piezoelectric disk would work.