2 ms·

That's pretty gnarly. So the discs are basically doing little inchworming steps back and forth but never has to break contact by modulating the friction? Very m

That's pretty gnarly. So the discs are basically doing little inchworming steps back and forth but never has to break contact by modulating the friction? Very much a bit of cleverness turned magic. The one thing that I notice is item 726/Fig 7./PDF pg 10, it has "with the soles and attached/embedded ultrasonic transducers". Is that maybe a different or older envisioning of this system? His shoes seemed totally normal. Just trying to wrap my head around how much the friction can be changed by vibration, like a solid-ish state fluidized bed. Don't know it both contact surfaces need to be vibrating.

Animats 3y ago
That's a cute system. Moving stuff around with controlled vibration is known. There's a cute trick where you drive a flat horizontal plate in three axes (X, Y, and rotate about Z). Sawtooth waveforms will move things around; the slow part of the sawtooth produces motion, and the fast part yanks the plate back to the starting point, breaking from static friction to weaker sliding friction. It's even possible, by using combinations of translation and rotation, to move multiple objects in different directions. The original research was funded by United Parcel Service. They wanted to take a table full of boxes, separate them, align them, and send them to a conveyor. Didn't work well enough, although someone did a chessboard demo where multiple pieces were moved around separately. This is a similar idea, but at a finer scale. > "with the soles and attached/embedded ultrasonic transducers" That suggests doing this in the shoe, instead of in the floor. Different system. Disney might license that to Nike. I can't see it for theme park customers. This system can make people fall down. Performers, though...
- gimmeThaBeet 3y ago
  Oh, okay, I see, in that alternative system, the tiles still move, but your shoe with transducers is used to adjust the friction.
blamestross 3y ago
The normal model of friction already has static vs moving friction. They just vibrate to switch between them.

Animats 3y ago

That's a cute system. Moving stuff around with controlled vibration is known. There's a cute trick where you drive a flat horizontal plate in three axes (X, Y, and rotate about Z). Sawtooth waveforms will move things around; the slow part of the sawtooth produces motion, and the fast part yanks the plate back to the starting point, breaking from static friction to weaker sliding friction. It's even possible, by using combinations of translation and rotation, to move multiple objects in different directions. The original research was funded by United Parcel Service. They wanted to take a table full of boxes, separate them, align them, and send them to a conveyor. Didn't work well enough, although someone did a chessboard demo where multiple pieces were moved around separately. This is a similar idea, but at a finer scale. > "with the soles and attached/embedded ultrasonic transducers" That suggests doing this in the shoe, instead of in the floor. Different system. Disney might license that to Nike. I can't see it for theme park customers. This system can make people fall down. Performers, though...

gimmeThaBeet 3y ago
Oh, okay, I see, in that alternative system, the tiles still move, but your shoe with transducers is used to adjust the friction.

blamestross 3y ago

The normal model of friction already has static vs moving friction. They just vibrate to switch between them.