One thing going slightly viral lately is footage of Disney’s “HoloTile” infinite floor, an experimental sort of 360° treadmill developed by [Lanny Smoot]. But how exactly does it work? Details about that are less common, but [Marques Brownlee] got first-hand experience with HoloTile and has a video all about the details.
HoloTile is a walking surface that looks like it’s made up of blueish bumps or knobs of some kind. When one walks upon the surface, it constantly works to move its occupant back to the center.
Each of these bumps is in fact a disk that has the ability spin one way or another, and pivot in different directions. Each disk therefore becomes a sort of tilted wheel whose edge is in contact with whatever is on its surface. By exerting fine control over each of these actuators, the control system is able to create a conveyor-belt like effect in any arbitrary direction. This can be leveraged in several different ways, including acting as a sort of infinite virtual floor.
[Marques] found the system highly responsive and capable of faster movement that many would find comfortable. When walking on it, there is a feeling of one’s body moving in an unexpected direction, but that was something he found himself getting used to. He also found that it wasn’t exactly quiet, but we suppose one can’t have everything.
How this device works has a rugged sort of elegant brute force vibe to it that we find appealing. It is also quite different in principle from other motorized approaches to simulate the feeling of walking while keeping the user in one place.
The whole video is embedded just below the page break, but if you’d like to jump directly to [Marques] explaining and showing exactly how the device works, you can skip to the 2:22 mark.
how? I would like to see schematics and motor specs.
I rather suspect the US Patent Office has those.
I politely disagree with the turning both ways part.
I believe they are set in groups of 31 arranged in an hexagon.
They are all ran by one single motor and each on an axle that can be tilted through a 45 degrees cone, most likely with a single actuator.
You would need 31 such groups to make the whole floor but they probably only need 20 cm of depth and a couple of controllers.
You tilt each group of motors as a unit so that the edge that is proud goes in the direction you want and as far as the users foot is concerned the whole floor is moving in that direction.
Both mechanically sturdy and easy to repair or replace parts.
So for a 50 by 50 grid there would need to be a minimum of 2500 motors, and to increase the Torque probably the same number of planetary gears.
It’s more likely a single large motor and 2 axis actuators that tilt the ‘mushrooms’ in multiple groups
Near the beginning of the video, it looks like the tilt angle is fixed, but can be rotated to control where the raised edge is. The top of discs were stationary, but there was a sleeve that was rotating while the angle changed.
So possibly one drive motor for the disc speed, and one motor to rotate the raised edge per hexagon.
Not necessarily… since each disk can tilt, they can all turn continuously in the same direction, with the tilt determining where the highest point of the disk is, i.e. the point in contact, which then determines the direction.
The title image looks as if the disks can independently tilt… I didn’t watch the video…
If the entire assembly only moves objects in one direction at any instant, it could all be done with 2 motors: one to spin the disks, with gears or chains to transmit the motion to each, and one to move a singular swash plate, with holes and connections at each disk.
They had 2 people on the device moving in two directions at once.
Yeah, the unit shown is divided into hexagonal subunits. All of the disks in a subunit tilt and turn together, but each subunit can tilt and turn independently. This allows multiple people to use the platform as long as two people don’t step on the same subunit.
It probably doesn’t need to control each motor independently. If all motors tilted the same degree and spun in the same direction, whole floor moves objects in one direction. You only need individual tiles about the size of one human foot, so that you can move each feet independently.
US10416754B2
https://patents.google.com/patent/US10416754B2/
Looks like they figured out a way to multiplex the motors so it doesn’t need a motor on every disc. One larger motor providing the driving force for the spinning discs with a matrix of steering servos controlling the direction.
Note the video version has them packed as hexagon modules; I’m guessing each one of those has the drive motor.
Speed read the patent, and one of the diagrams shows a motor under each pad and two additional motors with screw threads to control the angle of all motors in a square pod. Which I am guessing was an earlier revision.
For DIYing this… one motor for each 7 or 49 of the disks sounds like a reasonable compromise for build-ability and cost.
But one BLDC motor and planetary gearbox per disk is also an option.
Aim for 2m/s at first. That’s the rim-speed of the disks. From there you can calculate the gear ratio and how much power you’re going to need.
Another way to build a similar functionality is to simply turn a balled mouse upside down. And change the sensor things to actuating motors. Use rectangular grid and you can turn all the balls in one row or column with a single axle. Aaargh! You can run TWO rows with one axle!
Slightly tricky point is the bearings to have the balls run smoothly.
Did you notice inthe first couple minutes, Imagineers are using Valve Steam Decks for control and testing of their Star Wars droids?
Long as they don’t try it on any subs.
Disney seems to have some really talented engineers, if only the same could be said of their writers.
My first thought when I heard “Disney Mill” was very different (churning out crappy movies)
Make it impervious to fluids and easily washable and you have the perfect floor for a holodeck.
What about actuating the fluid in your inner ear remotely using e.g. magnets, to trick your mind into thinking that you’re actually moving? :P