Interesting, that is just a GPS tracker in a backpack with built in WiFi, you can get MUCH smaller GPS trackers (I work for a company that makes them) and it would be very easy to use it in a back pack, ours however send data over GSM or WCDMA, I'm not sure but I think out next upcoming model has bluetooth so may be suitable (but there are others that already have bluetooth). Ours are designed to track vehicles and are accurate to within 1meter (not as accurate a 2cm but accurate enough I think)..... but you can probably just use a smart phone with built in GPS and WiFi to do the same thing

What I have been doing with my backtop setup is just using a rug and walking barefoot. I have a rug in my living room, that is about 5 feet by 8 feet. Then I made sure there was about a foot of space around that with no obstacles. Walking on this barefoot its very easy to feel once I am touching the tile floor. And surprisingly I played on this for about 30 minutes and did not reach the edge once. But had I gone off the edge, it would have been easy to get myself back into place.

Yeah I know. I was just commenting on how this thing already has the accelerometer and GPS integrated. You just plug your computer into it, read off the earth coordinates (2cm accuracy is insane!), and feed those almost directly into the game. How easy is that? Now we just need a cheap DIY project to replicate it.

don't most smart phones have accelerometers in them as well? I can imagine that backpack will be as expensive as a surveyors GPS

Most GPS's are pretty crap indoors - so i'd be interested to know what its accuracy was like INSIDE.

I think the lack of an accurate absolute positioning system that works reliably indoors is holding everything back (such as AR) in this area.

Well I can tell you that indoor accuracy entirely depends on what the roof is made from, If you are in a concrete car park then your accuracy will be 0% same with metal a roof, if you are under a wooden or ceramic roof then it will work but accuracy will suffer depending on how thick the roof is weather you are on the 1st floor of a multi story building etc. GPS signals are coming from satellites in the sky so accuracy depends on how many satellites are in the sky above you and how many the tracker can see at any one time (the more the better) and the signal is generally not strong enough to penatrate through most buildings well, all GPS trackers generally are designed to work with clear view of the sky but will sitll function with reduced accuracy with some obstruction. Not an ideal soloution for indoors but for outdoors (like the soccerfield idea we were talking about) it could be utilised quite well I think

For indoors you would just use optical - of course this type of solution is going to be quite limited indoors. Maybe if you have a 3 car garage and you scaled the movements so that you were just shuffling your feet to walk you could still use this technique adequately. I'm actually quite interested in how much you can scale the movement and still feel an immersive effect.

I think theyd be a big market for a terrestrial type GPS where you could put 3 sensors/pingers in set locations then use them to calculate the coordinates accurately.

Really, it would solve so many issues, as it would let you use advanced GPS type positioning inside, without the hassle of optical.

We seem to have drifted off topic, it seems we are now talking about more of a freedom VR setup rather than an omnidirectional treadmill
So to bring this back on topic I recieved an email back from Zorb in China today.
A 2M diameter Water Ball (about 6.5ft) is $220USD and comes with a repair kit, the pump to inflate the ball is another $45USD
From this a guess the 3M Water ball (about 9.8ft) should be under $400USD (I have requested the price for the 3M now as well)

So add to this a paddling pool and you have a passive DIY Virtusphere, I think we could add some thickener to the water in the paddling pool to increase friction making it easiear to walk in the sphere

This setup could work well with a fully wearable VR setup

2m would be too small for most considering the movement and wobble of the ball plus a HMD would hit the ball i think. The other big caveats are having to have someone pump up the ball for you and let you out to the usage would be very limited. Great idea on the water thickener though.. what did you have in mind?

I only posted the price for the 2meter Water Ball because that was the only price they got back to me with, however amazingly they emailed me straight back with prices on 2.5M (8.2ft) and 3M (9.8ft) Water Balls and the good news is they are only $250USD and $280USD respectively! Add the pump and paddling pool and you have the makings of a Virtusphere for under $400USD. Yes there are drawbacks (needing someone elst to pump up the ball etc) but considering the price I think that it might be worth it, you could set up four of these for under $2000USD and play 4 player death match or 4 player coop! (obviously the cost of mobile VR setup x4 on top of that) plus if we can get this to work it is cheap enought that more people might do it, then we can get to gether a VR game server and play against other people with similar setups

As for thickener something like corn starch might work, will make a bit of a mess but worth trying out I think

The cool thing about these, is that it would be hard to hurt yourself falling... nice idea using the pool with the thickener...

Is anyone else uneasy about strapping a few thousand dollars worth of electronics on your body and then jumping in a pool? Something is not right with this picture.

Yes but inside a waterproof bubble..... no worse than running around in a large space with a few thousand dollars worth of electronics strapped on your body and tripping over and falling onto it, inside the bubble if you fall you will be less likely to damage your equipment I would think...

Just thought I would let you guys know that I am making a few small baby steps towards making an ODT.

Remember those gravity rollers I found earlier? They are perfect, except for the fact that they come in a very limited set of widths. Even the spurs would result in very steep angles, along with big gaps between the edges.

The solution? Make my own rollers, in exactly the sizes I need! I am going to do some tests with thick walled PVC and steel pipes, along with an assortment of bearings. If I can build 4 rollers as a test, it should be enough to see if they can be mounted well (In terms of closeness and rigidity).

Cool. The BF3 sim seemed like one of the more viable solutions that was discussed.

I'm also "putting my money where my mouth is" and implementing the WiiSpace idea. Just working on getting data from Wiimote and calibrating the boundaries right now, but everything is going smoothly so far. People were concerned that this did not meet the criteria of an omni-device, so I'll start a new thread when I have something to show.

@Palmer
Cool man, will be good to see how you get on with that, I agree with brantlew that the BF3 ODT does seem like the most usable idea if it can be done at reasonable cost

@Brantlew
How much space do you think you will need minimum to use a setup like that? I'd be interested to build a free walk system but space restraints are a pain in the ass for this kind of thing unless you happen to live in a warehouse
Also I just had a thought, for a freedom VR setup couldn't we just use the accelerometers in the Wiimote to detect what direction we are walking in? (forwards, backwards) we are already able to use them to track turning left and right, and if you use the pedometer activated nunchuck that palmer linked to a few pages back you can detect walking action as well.

Here are some brain-storming ideas that might have an application for the "walking in a ball" idea. For walking or running, you don' t need to track the user, but rather the ball itself.

A pair of regular optical mice, if placed anywhere on the ball at 90 degrees from each other should be able to track the users walk and pace. If the ball is in water, that may not be a good idea. But, perhaps rollers can be attached in the same locations and use optical encoders on those rollers.

A related idea what would require some image processing is to put some sort of texture or pattern on the ball and then aim a camera at the ball. The video processor would have to keep track of the movement it sees, both linear and rotations.

Another related video processing idea that would require more than a little optical processing is to place some sort of bar-code stickers on the outside of the ball at various locations. Then, the computer can identify the locations of specific bar-codes. It should then be able to extract the absolute position of the ball at any time. But, I don't think this is really necessary. Just relative motion should be fine.

Joe Dunfee

This half-baked idea is in regards to controlling the motion of the ball. Someone else commented that it is difficult to walk inside those giant pool inflatable balls because of the lack of friction. One proposal was to use a more viscous liquid instead of water.

I am trying to think of how to computer-control friction.

#1, Use a shop vacuum and apply a suction device to two points, 90 degrees from each other. The vacuum would run continuously, but at each suction point, a butterfly valve in the suction line opens or closes to allow the vacuum to create friction.

#2, Rather than suction, use air pressure blowing out of the suction device above. Such a device is referred to in industry as an "air caster". These air casters would have to be positioned near the lower portion of the sphere and be spring loaded to apply physical pressure to the sphere. When these air casters are blowing, they would reduce friction and allow the ball to roll.

I prefer idea #2, since there is positive pressure that would not tend to suck in the liquid like a vacuum. However, I have no idea if the amount of friction can be modulated. I.e. it might tend to be very full-on or full-off.

Joe Dunfee

OK, a little more brain-storming for today. These relate to the idea of projecting images on to a large ball with the user inside.

#1) If the inflatable ball idea is used, one of the interesting things about it is that they may be available in white, and allow for rear-projection. This eliminates all the head-mounted display problems with getting a wide field of view. I would suggest applying a dusting of some black spray-paint to the interior (or what ever would stick to the material used) to increase contrast.

One limitation I see with the above is that the ground could not be projected onto from outside. So here is an off-the wall idea, Use a light weight projector stuck to the top interior of the ball. You could also attach some optical systems to track the user's head location. This unit would have rollers on the top, and be held in place by magnets above the sphere. This set of magnets would have to be mounted so it would ride with the vertical motions of the ball as it bounces with each step.

The power would have to be transmitted inductively. I am not sure if this would be incompatible with using some of the standards for wireless video transmission.

#2) Another idea is to use micro-projectors and mount the projectors on the user's helmet so that they project their images on the sphere. Of course at this point you are talking about more than a little power consumption, but not so much that it would require a back-pack unless the computer running the simulation is also on the user. The problem I see with the idea of head-mounted projectors is that the user's head is moving in relation to the sphere. I.e. they would not align correctly unless they were arranged so that each of the projectors emitted their light from the same aperture, or at least, very close to the same aperture.

Joe Dunfee

@Machine: I really don't know at this point, however I think it would be inappropriate for indoor use. Right now I am only focused on outdoor situations and how well the system can scale. I hope that a 10x10 meter area would be sufficient - that would accommodate a typical backyard setup and the resolution at that size is really good. You should be able to detect position changes as small as 1 cm. I've been estimating how much the system will scale without adding lots of extra equipment. I think it can probably go as large as 30x30 meter and still be within stable bluetooth range and have a motion resolution of around 5 cm. At that size you may be able to play perceptional tricks on the player and have them walking in circles instead of hitting boundaries which would be a huge bonus.

I have also considered using the Wiimote inertial system to track position, but it's not dependable enough to trust boundary detection simply with a dead reckoner. I still need an external "absolute" positioning system and optical seems like the most straight forward solution to me. Down the road I might try using an inertial system for small movements coupled with an optical system for auto-correction, but right now I'm just keeping things simple.

Good news! I built my first gravity rollers out of cheap and easily available parts!

They are lightweight, stiff, and almost completely silent. I built them using skateboard bearings and wheels, black ABS pipe, and some nuts and bolts. Depending on how much bulk I buy in, a three foot long roller will cost between $6.75 and $11, with a 6" long roller (The smallest I can see using) would be between $5 and $8.

Unfortunately, the seller sent me wheels that were about half a millimeter smaller than what they claimed. Not a big deal for skating, but makes them a little too small for what I need, so I had to use a single wrap of gaffers tape. I will be buying some sets from other companies, to see if any of them have wheels that really are the size they claim to be/that I need.

That's bad ass!

My rough, ROUGH estimates for a 1 meter radius unit puts that at 20 rollers * $8 * 8 sections * 75% usage = $960. Not bad. Throw in another $1000 for mounting brackets, motors, belts, control boards and we're talking about a $2000 copy of the BF3 sim floor.

Where do you find the time for all this crap !!

Are you building triangular rollers? How many do you plan to use?

@Brantlew: The rollers are actually a little over 2' wide, a bit thicker than the gravity rollers, but not by much. Because of that, it should only need 16 or 17 rollers per section, maybe less (I am considering making the circle plate in the middle a bit bigger). As far as time, goodness knows I do not actually have much of it spare these days. I only spent about $20 in parts to make two test rollers, it took about 15 minutes to find the right parts online after the initial inspiration hit. I picked up the ABS pipe at Home Depot while I was already there picking up some supplies for my job, and it took another 15 minutes to put together the two rollers when my parts came. Less than an hour!

@Aphro: Yes, I plan on building triangular rollers. No idea when (It might be months). I am also unsure of how big I want to go. My plan right now is to build starting at the longer rollers (3 or or 4 feet or so) and building into shorter rollers (2 feet or so). If I need to, I will make the center plate smaller and build even further in (Maybe even down to 6" rollers), or build the platform out to be larger, with 4, 5, or even 6 foot long rollers. The nice thing about this solution is that you can pretty easily add on to the size!

Now I need to figure out the cheapest possible mounting hardware for these rollers.

Excellent. I'm excited just to hear you've taken the first experimental steps toward an affordable ODT. Please post some pictures. We could build wedgeroller ODTs for just a few thousand, it seems. With the HMZ-T1 (and the ST-1080, if it's real), a wireless video transmission device such as the WAVI, a battery pack, and various haptic peripherals and VR software, a fully complete cyberpresence system could be possible for under $10,000. Do the rollers have to be motorized?

Those roller skate bearings are nearly frictionless so you need the belt to add resistance or you would immediately fall the first step you took. And then of course then you need the motors to attenuate the resistance. If you pay attention to the video those wedges are each made of short sections - maybe 18" long instead of the full wedge diameter. A lot more motors are necessary but at least they can be lower power. Also I'm guessing if you try to run a belt the entire radius it might not evenly contact the rollers. That design also makes the system modular and expandable.

Beyond all the hardware, I suspect that there is a significant software component to drive all those motors at the right time and speed - and some way to track the players intended motion. We've got a long road ahead of us...

Where can I find info about the motors on this BF3 treadmill design? I'm having trouble finding it. I don't see why they are needed. If the incline slightly increases from center and the rollers have less resistance the further you move out from center I'd think that would work. Is the point of motorizing the rollers so you can stop and stand still on the rollers without being returned to center?

Palmer has inspired possibilities again!
Say we can build a small ODT how will the motor drive work? For simplicities sake I think we might get away with a single motor driving the lot at a single low speed for testing. As long as you walk slowly on the thing it should be ok. But how to drive the rollers? The only thing that comes to mind is a single full length belt under the centre of each roller section which has another set of skate board wheels inside full length to keep the belt pressed up against the rollers. Like a tank track system under each roller section. Now the belts would need to be driven by the wheel at the centre end of each belt connected by shafts with universal joints. So far no complex machining required.
An added bonus of the centre belt and wheels sections is that they will add weight bearing strength to the centre of the roller sections.

Was this taken for granted or are there other ideas?

Very cool, PalmerTech. I had thought maybe something could be done with skate parts. I look forward to see the progress on this.

I had another idea today though. I was leaving work, and the front door to the building was locked. Usually you just have to push it. While I was pushing it, I was detracted and playing with my phone. Keep in mind the door was totally locked shut. But since I wasn't looking at it, I had the feeling that I was really opening it, just that it was heavier than normal. When I looked up, I was surprised that my hand was actually almost a foot behind where I thought it was (where it would have been if the door was open). So this got me thinking. What if there was a contraption that completely immobilized the user (at least the legs), but had some sort of haptic feedback that would trick the user into thinking he was in fact moving. Maybe this could work. Any thoughts?

Given the amount of work and money in such a system, I wonder if there is a way to test it to some extent. Might you simply go somewhere that has a gravity roller system and ask to walk on it? I would only try very small operations, so that the chain of authority is very short... ideally only one person and someone who already knows you. Otherwise, they may tend to think about liability issues instead of how cool the idea might be.

I think the test would establish if you are comfortable walking over rollers at the diameter you are building them.

Another test method is to just draw the arrangement of pipes life-sized onto paper and place it on the floor. This will help you to visualize using it. Such exercises can help you to imagine it in use more concretely than if you are drawing on your desk top.

Since we are brainstorming, here an idea regarding a cheap roller system. Imagine vacuum forming a sheet of plastic over a bunch of pipe segments. Then, remove the plastic and drill or punch small holes along each groove formed. Assemble this to form an air-hockey table arrangement so that each pipe can be placed in a groove and it would be free to roll because of the air supply. If you have enough air holes, then you may be able to get away with plastic pipe instead of metal.

You would still want something to keep the pipe from rubbing on each end, but that doesn't need to be much. Perhaps a plastic ball sized to too big to fit completely inside can be glued into each end.

The drive mechanism might be accommodated by placing a strip of wood over the pipe before the plastic is formed over it. Then, that wood would leave behind a groove that a drive belt can run inside.

Joe Dunfee

No time to address everyone else, but as far as trying walking on a roller system:

Most gravity roller systems are actually pretty widely spaced, and they are almost totally frictionless. Walking on one would not tell me much.

I do plan on chalking out the size, and I also plan on spending a little bit of money building a single, non motorized platform. If that goes well, I will develop it further.

I haven't read every post here, but I think the only really economically viable option is the roller shoes.
The issues with this seem to mainly be related to four things:
1. using normal roller blades, you can only go forwards/backwards, not turn or strafe
2. It is difficult to limit the rolling so you don't just fall over.
3. How do you track the movement?
4. How to stay in the one spot?

So, my idea for these is:
1. Use some regular roller-skates (four wheels with two at front, and two at the back) except replace the wheels with these:
http://www.acroname.com/robotics/parts/ ... LER-3.html
2. If you have seen the 'soft closing' cupboard/draw mechanisms, they get a nice stiff action by just using a heavy grease. Most roller-skates use a fairly light grease to make them as friction-less as possible, so just washing the bearings and replacing the grease should get a nice and consistent friction.
3. The main Idea I have here is to use the sensor out of a regular optical mouse, mounted with a spring that will press it against the ground lightly when you put your foot down. The movement tracked by the mouse will be opposite to what you want as input though. Also, you need two mice to track both feet, which will make it difficult to write a driver for.
The other option is to track the wheels, but this would be more difficult.
4. I believe a harness that just goes around your waist with some elastic attached to four (or more) points on a heavy frame is all that would be needed.

I've too many other projects on the go, but if anyone was going to implement the omni-shoe concept, the following might help:
http://www.ebay.com.au/itm/Omniwheel-Flexiwheel-RS02WE-Robot-conveyor-omni-wheel-/220864574281?pt=BI_Robotics&hash=item336c8df349#ht_2239wt_1139

OK! Now we are talking! This looks very interesting. I wonder how hard it would be to retro-fit those wheels onto a pair of roller-skates? That certainly seems like the most affordable suggestion so far. Those wheels were like $7 each, for 4x thats $28. Maybe $100 for a pair of skates. And the tracking could use multiple off-the-shelf equipment (Wiimote, Kinect, etc.) and only add maybe another $100 to the cost (not counting the computer and all the other stuff). I'd like to explore this further.

Those wheels don't look like they can bare much weight. That aside, if you make some skates from them, what then? Doesn't that only leave you with the option of suspending your full weight in a harness and just have you feet touching the ground for walking motions and still having an issue with turning?

I don't believe you need to be fully suspended in a harness. the harness prevents you moving forward, backward, left, right and turning. your full weight would be on the wheels. you'd have to test the wheels for weight, but think they would be good enough for testing. There are similar products that are all metal that could be used in a final product if found satisfactory.
The sensors on the shoes would monitor the floor position relative to your shoe, which will be the exact opposite of your movement relative to the ground if walking normally. This would probably need two sensors per shoe to get turning as well as forward/backward, left/right.

I think an ideal setup would actually use only 3 wheels per shoe. one in front of toe pointing left/right and two just behind the heel so they are at 60 degrees to the front one. Ideally these would also have powerful supper motors attached to keep the wheels all moving at the same speed though.

Well this is interesting. One of the more practical ideas that came out of this thread was just simply using a Kinect to track gestures and stationary walking. Well this guy went ahead and did just that. Not as exotic as many of the other ideas put up, but you gotta admit this solution is simple, cheap, requires minimal space, and achieves many of the goals of a natural motion system. So is this more immersive than a button controller? You be the judge...




http://zookal.com/blog/2012/03/how-to-play-skyrim-in-virtual-reality/

Only interesting if it works in 360 degrees.

I am sure it could, the Kinect is pretty good at handling rotation.