Envisioning a DIY CyberCarpet for Omnidirectional Motion

Post by **mAchiNE** » Sat Oct 22, 2011 5:07 am

brantlew wrote:I like mAchiNE's idea of using lower profile bearings and sinking them into thick soled shoes to minimize the height impact. The second unit looks more realistic to me since the first one is so wide that you would not be able to fit many together. These are all really large bearings (1" or so). At that size we could only get a few of them on there and they would really be more like rollers skates. Have you guys run across any smaller size bearings - maybe in the 1/2" range?

http://newzealand.rs-online.com/web/p/b ... s/0687821/" onclick="window.open(this.href);return false;
15mm ball bearings in this assembly (0.59")

Post by **pierreye** » Sat Oct 22, 2011 10:56 am

I actually aiming for this.
http://malaysia.rs-online.com/web/p/products/0687635/" onclick="window.open(this.href);return false;

Just need to cut off the bolt fitting. The problem with flange unit is you can't mount the ball transfer unit close enough due to the fixing centres = 29mm. Bolt fitting is cheaper too. I estimate I need 50 units for the whole project and come close to USD 300. Now I'm thinking if I can go cheap first to try out the concept by getting a bowl shape fiberglass, put some baby powder on it to make the surface slippery and wear socks.

Or use a children sandbox such as this (Diameter close to 4') or 4' satellite dish.

http://www.amazon.com/Step-2-740500-Cra ... 388&sr=1-6" onclick="window.open(this.href);return false;

Post by **cybereality** » Sat Oct 22, 2011 12:51 pm

Not sure if this has been mentioned or not, but is there any reason an off-the-shelf pair of roller-blades could not be used?

You would need a harness, and probably some sort of curved bowl to walk on, but it seems like a really affordable and no-nonsense solution.

Post by **PalmerTech** » Sat Oct 22, 2011 12:55 pm

Hard to turn. Omnidirectional shoes would probably have the front tip of the shoe made of a rubber pad, so you could stand still and turn easily.

Post by **cybereality** » Sat Oct 22, 2011 1:08 pm

Its possible to turn with roller-blades. Obviously harder than wearing sneakers, but I think it would be even easier than with the omni-directional ball bearings we are talking about. And you could probably get brakes installed on the roller-blades (front or back) pretty easy, and its all off-the-shelf stuff.

Post by **mAchiNE** » Sat Oct 22, 2011 4:03 pm

yes but you can't walk sideways in rollerblades and stay in the same place like you can with ballbearing shoes

Post by **cybereality** » Sat Oct 22, 2011 5:29 pm

@mAchiNE: Well, yeah. Walking sideways would not be possible, but that seems secondary to forward and backwards motion.

Just trying to come up with something that is realistic. Dunno about you, but I certainly don't have $5,000 to spend on a cyber-carpet.

Post by **Okta** » Sat Oct 22, 2011 6:09 pm

How about these instead

Post by **cadcoke5** » Sat Oct 22, 2011 6:41 pm

Regarding all of the VR related motion devices, I have always had a doubt about the ability to navigate it easily. My doubt is because most of them can't simulate the user's inertia. E.g., when you stop, a person will actually lean back for a short time to compensate for his sudden deceleration. You make similar compensation when you start moving or turn. Furthermore, you experience the forces on your feet.

The "Hamster ball" VR environment;

The only exception I can think of to my concern over inertia, is the giant hamster ball. In that, when you stop running or walking, the ball tends to continue rolling, so the user must compensate in a similar way to stopping on flat ground. If the ball's rotational inertia is equal to the forward inertia of the user, then it is a build-in solution. But, when the user has stopped the ball's rotation, then the user is beyond a neutral position. The ball would roll back, and then over-shoot the neutral position. The user would have to compensate by leaning forward. The real world doesn't work like that. However, perhaps the system automatically applies brakes to stop the ball from that roll-back situation. Regardless of the method, the demonstrations I have seen of the hamster ball show that users are able to use it. The main problem is that this is not something to home-brew.

Roller shoes;

For the roller shoes discussed here, I suspect that they won't be viable. I have a little experience walking on ice, and it is a difficult thing to do. I suspect the harness will be carrying your weight most of the time. I think the experience would be like using your feet like a computer mouse.

=========================================
My own suggestion on a hackable VR environment

I have always thought it would be easiest to simulate the user on some sort of scooter. Another user here suggested a jet-pack. Car and plane simulators are another example, but perhaps they are more removed from the environment than something like a 4-wheel ATV.

I picture the user seated on an ATV or scooter of some sort. Then, this hanging by a cable from the ceiling. Actuators can push the ATV in any direction to allow the user to feel as though they are accelerating or stopping. The final touch would be for an actuator to simulate bumps in the road by pulling on the cables the ATV is hanging from.

Joe Dunfee

Post by **WiredEarp** » Sat Oct 22, 2011 7:21 pm

@ Okta: thats actually a pretty good idea. those shoes are already low profile and have rollers!

@ cadcoke: I know what you mean about the inertia effects, but the question remains if they are really necessary to provide a realistic sense of walking. I suspect that the motion of walking is much more important to this sensation than the inertia on stopping.

Actually, regarding this as well, while its good and nice to aim for a 1:1 realism mapping between reality and VR, this may not be required, or even wanted, by the vast amount of users. I've been surprised how easy it has been to get used to doing 180 turns to turn 360 (with both my gun and helmet providing turning input) and in fact, as long as you dont NEED to map to the real world, its more fun to use and still JUST AS IMMERSIVE, if not more so (probably due to the head movement). I think PalmerTech hinted at this earlier when talking about his stage setup at his work. He mentioned that many people preferred 'accelerated' movement.

I suspect that once we all start playing VR games etc, 'accelerated' movement may actually become more popular than real world movement. After all, given a world we can make our own, who wouldn't want ot be able to jump further, run faster, turn quicker?

Post by **brantlew** » Sat Oct 22, 2011 9:10 pm

The last couple of posts about the importance/unimportance of inertial effects got me thinking about another novel idea. This is definitely not on a DIY scale, but it seems near perfect as an institutional VR room for a single user. Imagine an empty rectangular room - say 100ft long and 50ft wide. The entire ceiling is decked out with optical sensors for accurate full body tracking. The user is only equipped with HMD equipment. All movement is natural and unimpeded. This is similar to the facilities that Palmer has described before.

The cool thing about this room however is that you can walk uninterrupted in a straight line forever in it. Here's how. The floor consists of two giant computer controlled rotating circular pads - each one 50ft in diameter and near touching at one point. As you move outward toward the edge of a circle, it will gradually rotate so that as you step off the edge of one circle, you will be stepping onto the edge of the opposite circle. The floor basically does it's best to keep you always traveling towards the center of the room and if successful, you will never hit a wall.

Here's an example. The colored lines represent the path that the user takes along his journey. The user starts in the center of the bottom circle and starts walking northward along the straight blue line. As soon as he crosses onto the top circle it begins a slow 180 rotation so that by the time he reach the center he is facing south. Now he will follow the green path on his southward march back to the starting point.

Here is another example of a user that starts out on an eastward trek. (EDIT: Oops. Just realized that the top part of this path should be curved just like picture above. You get the idea though.)

As long as the circles are large enough and the acceleration graduated the user will feel no angular momentum. That combined with the immersive visuals will convince the user that he is walking in a straight line. This could go on indefinitely. There is no limit to the size of the virtual world. It just has to be flat. In practice there are some problem areas in the fulcrums between the circles that might have to be dealt with, but in principle the user could make any sequence of turns and movements and never hit a wall.

Am I crazy? Am I missing something crucial here or would this work as I have suggested?

Post by **cybereality** » Sat Oct 22, 2011 9:25 pm

@brantlew: Thats an interesting idea. I feel like it may have issues if the user were to strafe while he was near the connecting point. But if it were mostly linear motion, I think it could work. The question would be if the user would feel the circular motion, and if this would ruin the simulation.

Post by **WiredEarp** » Sat Oct 22, 2011 9:50 pm

Haha thats a pretty cool idea. Be fun to play with additional effects you could provide by having a moveable floor

Post by **brantlew** » Sat Oct 22, 2011 9:57 pm

I believe it's just a matter of scale and speed. You have to keep the radius large enough so that the circles can accelerate at an imperceptible rate for the time it takes for the user to cross one radius. The faster the allowed speed, the larger the circles need to be. I picked 50ft diameters out of thin air just thinking in terms of walking speed. To handle fast running would probably require much larger circles but the principles are the same.

Really the worst part of this design is the large size required - but in terms of complexity this is actually one of the simplest mechanical designs that I have seen. Mechanically, it could very well be a DIY project. It's just that nobody has a gymnasium size space to work with.

Post by **brantlew** » Sat Oct 22, 2011 10:15 pm

@Cyber: The examples given use simple linear paths to illustrate the idea, but I believe that any change in direction and path could be handled. Viewed from overhead, the path would look really complicated. It also gets tricky right at the junction between circles if the user decides to do a 90 degree turn at that exact moment. Then they will be traveling out-of-bounds in the fulcrum. The one thing that helps though is that the distances are so large that they have ample opportunity to accidentally step back into the circles, and once they do that their path can be corrected. I guess as a back-up mechanism you could put triangular treadmills in the fulcrums that would try to guide the user back to the center (just like the Battlefield 3 simulator floor we saw earlier)

Post by **brantlew** » Sat Oct 22, 2011 10:43 pm

Alright if you will allow me one final outlandish idea...

I misspoke earlier. You CAN simulate angled terrain on this thing as long as you put the entire room on a single 2DOF motorized platform. So if you wanted to simulate walking a straight uphill mile, you would still have the path given on the first image but the platform would always keep you facing uphill. The whole room would move like a wobbly see-saw as you walked back and forth between the circles.

I'm know I'm being ridiculous, but it's only because I'm talking about the ultimate solution in VR rooms. I mean if you loaded in the Google Earth terrain maps, you could honestly walk from Florida to California! How's that for open ended!

Post by **WiredEarp** » Sun Oct 23, 2011 1:27 am

Here is a question for those with Novint Falcons. What is the potential up down travel of those?

Basically, what we require for my envisioning is a pair of falcon type devices with enough up / down travel to enable lifting up my foot to a reasonable height. All else will be done in software (turning, jumping, walking, etc) with the falcons providing force feedback of the surface. IE, we are replacing the hand attachment of a Falcon with a foot attachment.

With enough travel on devices like this, you could kick and jump with a reasonable simulation of reality. You could even have your virtual kicks be checked.

If most of the users weight is taken up by other devices (harness/saddle) then you could achieve it without requiring big systems that need to support your entire body load - they will just have to move your leg weight.

Post by **Synexious** » Sun Oct 23, 2011 1:47 am

Excellent idea, Earp! Sounds like you're envisioning an omnidirectional elliptical device. I wonder how that could be built, or if someone already has made such a product. A heavy-duty device could be built that takes on the whole weight of the body. That might be the best compact and relatively affordable way to achieve ODMiP (Omnidirectional Motion in Place).

Post by **brantlew** » Sun Oct 23, 2011 7:53 am

@Earp: It's a solid idea. The best thing about it is how compact and versatile it would be. The mechanical build would be daunting - to say the least. Not sure it would fall into the DIY category, but it does seem like something that if done well could be very realistic. The more load bearing the device, the more realistic it would feel. An additional advantage is that you could simulate all types of terrain - stairs, inclines, rocky, even slippery terrain could be modeled. Novint would definitely have a head start on this type of device and could leverage a lot of their existing R&D.

Post by **Synexious** » Sun Oct 23, 2011 8:54 am

Wow, you're right, any terrain could be simulated, which isn't possible even with the most expensive ODTs. But you couldn't cross your legs over each other, and you wouldn't have free range of motion to dance and kick.

Post by **cybereality** » Sun Oct 23, 2011 10:16 am

The Falcon can move within a 1 foot cube (maybe a little less). It would certainly not be enough for a foot attachment, and I don't believe its that strong anyway. However a similarly designed haptic device could work, provided it was much larger and strong enough to handle foot movement.

Post by **PalmerTech** » Sun Oct 23, 2011 11:54 am

Can't find the link right now, but there was a military project like that at one point. It used two industrial robotic arms with a strap for each foot, and could simulate almost any terrain (Including stairs).

As I recall, one of the main problems was the immense fear of everyone who used the system. A single malfunction or slip, and the robotic arms might break or sever your foot/leg!

It was a long time ago, and I know that modern robotics systems have a lot of failsafes, but I would be pretty scared of anything DIY that can exert so much force.

Post by **Synexious** » Sun Oct 23, 2011 6:41 pm

Couldn't the force just be limited?

Post by **Fredz** » Sun Oct 23, 2011 7:08 pm

Your discussions are very interesting, you got me looking for more on YouTube.

Found this, perhaps related to what PalmerTech was talking about :
[youtube]http://www.youtube.com/watch?v=4BkY8LGjW4w[/youtube]

This thing seems to be in the same vein :
[youtube]http://www.youtube.com/watch?v=RDDH1iqoDzU[/youtube]

Also found something about your idea of balls in the shoes. It's quite weird, not realistic, but could be quite nice for video games still if a solution could be found to have the hands free (maybe only with a harness). Read the comments of the video for more details about how it does work :
[youtube]http://www.youtube.com/watch?v=n3U8enNlhqM[/youtube]

And this last one could be useful coupled to another walking emulation technique, for example in a war FPS where the floor could by made of snow, concrete, sand, mud, etc. :
[youtube]http://www.youtube.com/watch?v=S3P2lKVDMXk[/youtube]

Keep on the discussion going, that's a nice brainstorming to follow...

Post by **cybereality** » Sun Oct 23, 2011 7:43 pm

@Fredz: Nice finds on those videos.

Hmm, those ball shoes do not look realistic at all. Seems like the guy is just walking on ice.

Post by **WiredEarp** » Sun Oct 23, 2011 9:29 pm

@ Aphradonis: you could achieve leg crossing and kicks etc, by having the leg Falcon mounted to another Falcon type arm. With the right articulation combinations, you could allow lots of movements. It would require some quite nifty/tricky software to perform the correct articulation to prevent binding on another control arm, but would definitely be possible. All of this would be part of the gradient of solutions that could be based on the same tech.
You could have a lightweight one that required user supported weight for the home, but arcades could provide systems that did full weight support and provided stronger feedback etc.

Great links Fredz. The first one seemed the best to me, scary stuff however.

Personally, I dont think we should get too hung up on this idea needing to support our weight fully. Of course, if it could, it would be perfect. However, (falling back to my main VR knowledge) remember Lawnmower Man?

The full motion solution in that was not weight supporting. They were in a 360 degree hoop harness, so most of the body weight was taken by the harness. If you actually had a hoop harness like that, you could have the falcons on sliding rings and could use them to provide feedback.

I think for us in a home setting, it will be possible for us to create a Falcon type walking device, safely, IF THE USERS WEIGHT IS SUPPORTED.
If we need to increase the lift capacity to support a human, and have no other harnessing, then we will have massive safety issues and it will cost a LOT more.
I reckon that even a 'walking desk chair' type interface where you sat and moved your feet, like walking a roller chair around, would be more immersive than current, and if we could have a system with a harness or chair (I learn towards the chair, easier to get on and off etc) we would save ourselves much hassle.

In the simpit arena (which we could probably learn something from since these concepts overlap with force feedback simpits) its quite common for home based motion simpits to have most of the weight of the simpit and user supported by counterweights, bungees, etc. This means a tuned simpit can produce strong forces, without having to lift the entire user + simpit.

I have to say, all this talk of walking around inside VR's, both in this thread and PalmerTechs one about his work stage, has really stoked my interest in giving a freewalking VR a try, just to see how much more immersive it must be.

Post by **WiredEarp** » Sun Oct 23, 2011 9:30 pm

Oh, and that 3rd video is just begging for some chicken dance music.

Post by **pierreye** » Sun Oct 23, 2011 10:25 pm

Looking at the ball shoe video, I think we can scrape the idea. Doesn't look natural and having to hold the rail doesn't work for FPS. Feels like going through physiotherapy after a major accident.

Post by **Synexious** » Sun Oct 23, 2011 10:38 pm

WiredEarp wrote:I think for us in a home setting, it will be possible for us to create a Falcon type walking device, safely, IF THE USERS WEIGHT IS SUPPORTED.
If we need to increase the lift capacity to support a human, and have no other harnessing, then we will have massive safety issues and it will cost a LOT more.

So could two Falcons plus a harness be used to create an ODMiP system? Would it really be that simple and cheap? Or would we need bigger Falcon style devices? Someone said the Falcon can move in a one cubic foot volume. Is that enough for natural walking? Certainly not for running. How could we build bigger, heavy-duty Falcons?

Post by **WiredEarp** » Mon Oct 24, 2011 3:09 am

It would probably be movement enough for walking, but I doubt it would have enough force to provide meaningful feedback. Since its designed for arms, it would probably take twice the power to handle legs, with their greater mass.

The same thing could also be designed to attach to wrists to provide force feed back for arms etc (bit like that Novint XIO, only externally mounted). Of course, the mechanical complexity would mean it wouldn't be feasible except for more highly priced installations.

Post by **Fredz** » Mon Oct 24, 2011 8:11 am

Found two other projects related to walking in VR environments. I also found more info and videos about the first one which didn't convince much people, but this time it looks a little bit better.

This page presents videos of these devices and others related to haptic or locomotion interfaces that were presented at Siggraph, all created in the Virtual Reality Laboratory at the University of Tsukuba in Japan : http://intron.kz.tsukuba.ac.jp/~yano/MA.html" onclick="window.open(this.href);return false;

Virtual Perambulator (1995)

On this one you'll find two MPEG videos of very bad quality, but they show much better than the previous one how the device is able to emulate walking, while wearing an HMD.
http://intron.kz.tsukuba.ac.jp/oldresea ... h/txt.html" onclick="window.open(this.href);return false;

This page describes the experiment at Siggraph 1995 and gives a little bit more details about how it does work :
http://www.siggraph.org/s95/S95_V1/COMU ... RAMBUL.HTL" onclick="window.open(this.href);return false;

Powered Shoes (2006)

Presentation of the project :
http://intron.kz.tsukuba.ac.jp/powereds ... oes_e.html" onclick="window.open(this.href);return false;

The device is in the same vein than the previous one, but without a harness and with more freedom of movement :
[youtube]http://www.youtube.com/watch?v=C5hPyHxrz94[/youtube]

String Walker (2007)

This one presents an original device that does use strings to move the feet to simulate walking ;
http://intron.kz.tsukuba.ac.jp/stringwa ... alker.html" onclick="window.open(this.href);return false;

A video of the device :
[youtube]http://www.youtube.com/watch?v=hyLKjyL-Dw8[/youtube]

Post by **PalmerTech** » Mon Oct 24, 2011 1:40 pm

Too busy to comment on everything else at the moment, but I saw one of these today, got me thinking.

Edit: Had to add this.

Post by **PalmerTech** » Mon Oct 24, 2011 4:31 pm

Double post, but relevant: Everyone in this thread needs to watch this video of that BF3 simulator, they actually show how the ODT works several minutes in: http://www.youtube.com/watch?feature=pl ... g8Bh5iI2WY" onclick="window.open(this.href);return false;

I hate to admit it, but they did a really good job on this.

Best of all? I found out about these things called "Gravity rollers" or "gravity spurs". They use them in assembly lines:

Even more promising? Look at this!

If we could get one that is angled on either side, then we are more than halfway there! I don't have the time at the moment, but these are definitely something to research.

@Fredz: What you posted looks a lot more reasonable. The thing I was remembering was literally two industrial robot arms, big huge ones.

I posted that walking machine picture in my last post, seems like a low friction version of one of those might be useful. Still need turning, though.

As far as harnesses go, I have to confess that I am not a fan. You need them for balance/safety, but muscle tension is a very important force for realism. Heck, in the motion simulator world, they make "seat movers" that do nothing by slide you forward and back, left and right in your seat. The steering wheel pulling away from you when you accelerate and pushing towards you when you brake is supposedly a pretty immersive force.

Post by **cybereality** » Mon Oct 24, 2011 5:39 pm

I'm a little partial to the idea of cyber-shoes. Only because they would seem cheaper and more practical for people with limited space. Its also something that is portable, could be brought places to demo, etc. So I am still holding out for some sort of cyber-shoes. I think even standard roller-blades could be used with the right setup. I mean, if you look at the video of the powershoes, they only move forward and back. As long as you know you cannot strafe with them, its usable. But a circular pod with a roller-floor might feel more realistic. Just trying to find something affordable here, but I love the discussion.

Post by **Synexious** » Mon Oct 24, 2011 8:43 pm

I found a loose ball supplier. I'm trying to find pricing. Ball bearings, bought in bulk, as Palmer found, are $2.00 each. The CyberCarpet, which is barely large enough to walk on, uses 4000 balls. So ball bearings cost too much. If loose (probably solid) plastic or rubber balls can be bought for less than a dollar each, they would be affordable. I'd like to have at least 8000 balls, double the Cybercarpet. Then put a rotating treadmill underneath. That would cost maybe one or two thousand at least, though, so maybe the price would end up being the same as with ball bearings, hmm... Maybe a true ODMiP platform can't be built for less than $10,000. Still, $10-15,000 compared to $50,000+ is good. It's something a dedicated uber-enthusiast could save up for.

Post by **Okta** » Mon Oct 24, 2011 9:28 pm

PalmerTech wrote:Double post, but relevant: Everyone in this thread needs to watch this video of that BF3 simulator, they actually show how the ODT works several minutes in: http://www.youtube.com/watch?feature=pl ... g8Bh5iI2WY" onclick="window.open(this.href);return false;

Wow. That sim is brilliant they did an amazing job for sure. I gather they didn't do 3d because the software used to mesh the projectors was not compatible. But that floor system is the bees knees. Any of us could DIY the rest with a decent HMD and some haptic/tracking gadgets but the floor is the key we will always lack

Now we have talked over so many methods... The original topic post of the omni bearing mat has high potential, a bearing mat over a normal treadmill that can rotate with the user is all it would take. Unfortunately the research team shown in the vids are still struggling to make it a reality...

Palmer, you have used the Virtusphere yes? http://mashable.com/2010/03/19/vr-hamster-ball/" onclick="window.open(this.href);return false;

I remember you saying it was lack luster but...looking over our other options... i think it still has potential. You have lots of experience casting fibreglass?

Post by **brantlew** » Mon Oct 24, 2011 9:59 pm

That floor is tantalizing. I wish I could see an extended demo of just a lot of walking around on it. It's difficult to tell how good it is from the video. My impressions are that can only handle a medium walking speed at most. There seem to be some minor balance issues that make it look a little unnatural. Still...apparently an untrained person was able to just hop up on it and use it without major issues so that is impressive. It was great to see them constructing it. It's as mechanically simple as we had all envisioned.

Post by **Okta** » Mon Oct 24, 2011 10:19 pm

PalmerTech wrote: Even more promising? Look at this!

If we could get one that is angled on either side, then we are more than halfway there! I don't have the time at the moment, but these are definitely something to research.

Looking at that it seems it can be flipped so 8 of those would make a square. If it is large enough and the price it right we are half way there. I wonder if the frame edges sit higher than the rollers which would be an issue. Also a circular plate can go over the centre of the assembly for a base like the BF3 unit. A single motor could drive the lot with either a single speed to keep driving you towards the centre or speed adjusted for distance from centre.

Edit- On second thoughts that would only give 4 directions which would lead to tripping and spinning... 5 or more pie shape sections would be better.

Post by **brantlew** » Tue Oct 25, 2011 12:53 am

Palmer and Okta: Good finds. Even if that triangular frame could not be used directly, there might be enough raw material in it for a really good start. Specifically you have the rollers already cut to all the sizes you would need. You might just need to get some steel frames to create the "pie" shapes and then cut holes to remounting the rollers.

Post by **mAchiNE** » Tue Oct 25, 2011 12:57 am

Okta wrote: I wonder if the frame edges sit higher than the rollers which would be an issue.

As its part of a modular assembly line the frame must sit lower than the rollers so the items traveling on it can pass from one roller module to the next un interupted so this is not an issue.

EDIT: @brantlew I like your Idea about remounting the rollers, not only does it mean the pieces will be the shape we want but also we can minimise the gap between "pie pieces". I guess it all comes down to how expensive they are? because it will need to be paired up with a fairly high spec (probably expensive?) tracking system