Force feedback motor? What's the best kind for me?

Forum 2005-2010 (read only) Hardware Interfacing
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Ok, so I'm thinking of trying to start a project. To put it simply, I'd like to do a home VR system. Something where you plug it in to your computer and strap yourself in, not taking up the space more then a computer chair.

There are VR systems, but they are really large. For instance, the sphere like one shown at GDC this year is near two stories tall of a ball, and has no feedback to a hill or steps, or anything but flat ground.

What I'd like to do is some kind of walking system where you strap it on your legs, and you're kind of hanging from it, but I want a response if you start to walk up a hill to put more strain on your legs. So, I'd need something that works like a servo (going in only so many degrees) and something that has enough strength to stress you, but not so much strength it would hurt you, and could be used a lot.

Any idea's on the kind of motor I would need for this? Would a larger servo work?

Did I put this in the right forum?

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O-o?? Anyone have any suggestions?

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What I'd like to do is some kind of walking system where you strap it on your legs, and you're kind of hanging from it, but I want a response if you start to walk up a hill to put more strain on your legs

What's your public liability insurance like?

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What I'd like to do is some kind of walking system where you strap it on your legs, and you're kind of hanging from it, but I want a response if you start to walk up a hill to put more strain on your legs.

Don't do this; please, just don't. If you do, you will be disappointed.

Setting up a system like this makes no sense from a computer interface standpoint. Why "walk" someplace in a virtual context, when there isn't any real need for it? You need to go someplace in a virtual context, teleport. Instant x/y/z/yaw/pitch/roll 6DOF coordinate transform; figure out a way to do this intuitively (within a completely immersive environment, no less), and you will have a worthwhile system.

What you are proposing is akin to the VR file system described/shown in Michael Crichton's book "Disclosure" (and the movie by the same name). It is a completely impractical method of interaction with a computer in a virtual environment; it will do nothing but tire the user out, instead of letting them get on with real work.

Instead, if you want a solution that is more practical but still fits into the space requirements, you would do well to mimic this:

http://flogistondesign.com/flostation.htm

Something like this, with perhaps one of those 3D LCDs (instead of the dome), plus maybe some form of hand and head/gaze tracking, would be ideal for a compact virtual environment workstation. It would allow for long-term working in such an environment with less fatigue than upright sitting or standing (or suspension), plus the design ("zero gravity chair") means that immersion becomes more complete.

The flostation design, however, is patented (being a combination of the "zero gravity" position and some other position related to yoga, IIRC) - but the "zero gravity" position is essentially "public domain", something studied by NASA. Furthermore, many companies have built and sold these chairs; you can even buy a pool lounge chair version from Harbor Freight for $50.00.

As I noted, though, the greater problem is in designing the UI for such a system, for navigation and interaction; this is a great open area of exploration and research - there have been very few successful methods developed (one of the best in my opinion has been the "point-and-trigger" method of such systems as the W Industries Virtuality pods - if one could couple this with a glove and gesture system, along with visual, audio, and tactile feedback, it might be a winner).

Good luck in your research and exploration; I've been playing with this kind of stuff on and off again since 1993 - I would advise you to pick up and find as many books from the 1990s as you can regarding virtual reality; if you need a good list, PM me and I will give you a list (I need to post such a list to my site, actually).

:slight_smile:

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Any idea's on the kind of motor I would need for this? Would a larger servo work?

I still stand by my previous comment, but to answer your real question (which I didn't before):

You would probably want to pneumatics or hydraulics to act on the joints, and transfer power using high-power (probably custom, too) servos.

Basically, you would have a large servo (say something like a windshield wiper motor/gearbox), where the servo arm acted upon a single-ended pneumatic or hydraulic cylinder, which would transfer the force via hoses to another single-ended cylinder which would act on the joints of the user.

I am postulating custom servos rather than large-scale R/C (with/without custom gearboxes) or industrial servos, simply from a cost standpoint - no matter how you look at it, your system isn't going to be cheap to implement.

Alternatively, you could also use pneumatic or hydralic pressure in closed-off lines to simulate pressure/resistance (think of how a garden hose stiffens up with water pressure). You can use the servo system I described above to pressurize things, or you can use a real pneumatic/hydraulic system (with pumps, hoses, regulators, pressure chambers, solenoid valving, etc - be prepared to spend some dough here, even if you buy used components).

One other thing: If you decide to go with a hydraulic system, be aware that in a real hydraulic fluid system that the fluid can be corrosive and at pressures/temperatures high enough to cause injury (not to mention one hell of a mess indoors). You might want to stick with pneumatics (which would provide more than enough resistance to work against), or use a working fluid in your hydraulics that isn't hazardous (like water or mineral oil), and run at lower pressures.

Good luck.

:slight_smile:

[edit]Oh - one other thing - look into "air muscles" as feedback actuators - they may be useful for what you are attempting to do...[/edit]

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Well, my idea wasn't really for a long work day, but more for just walking in a virtual park or playing paint ball with your friend that moved to japan or something like that. It's meant purely for an hour or three of quick games. Also, I personally think it would feel more immersive to actually walk in the environment rather then sit with joysticks. I can see that being better for longer sessions of work and such, but as far as for gaming, the only difference with that system that I notice from regular gaming is the chair and having an enclosure around the user and the screen.

I don't mean to say that it's not a bad idea, just not the same kind of immersion that I want. As for the hydralic/pneumatic system as well as the air muscle, I'd be afraid of what happens if something goes wrong. Hydralics don't give in all that easy, and if someone's not expecting it, a sudden jolt from the game engine could physically harm someone, which is NOT a good thing from a company's perspective. Lawsuits and such being what I mean.

I would need something that's soft as far as strength goes, but strong enough to make you feel that you're walking up a hill, rather then just walking forward.

Thanks for the suggestions though :slight_smile: I appreciate it, and I intend on going forward with this still XD Just need to find the right motor/pressure system.

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Well, my idea wasn't really for a long work day, but more for just walking in a virtual park or playing paint ball with your friend that moved to japan or something like that. It's meant purely for an hour or three of quick games.

Haven't spent much time in immersive environments, have you? You may want to research "simulator sickness"; there's also a related issue (can't remember the name right now) in which after being in an immersive environment for a long period of time, then exiting, the "real" environment becomes somewhat "unreal" - they make pilots take a period of time off of flying after long sessions in full motion flight simulators. The level of immersion is the main issue; the more immersed you are (and the longer you spend immersed), the greater the effect. Simulator sickness, however, is another thing - everything from lag to sounds to optics focus, etc - plays into it; headaches, nausea, etc are common.

Also, I personally think it would feel more immersive to actually walk in the environment rather then sit with joysticks. I can see that being better for longer sessions of work and such, but as far as for gaming, the only difference with that system that I notice from regular gaming is the chair and having an enclosure around the user and the screen.

You would think, but it isn't necessarily true; I suppose if you are trying to simulate earth-based (or similar) environments, then sure - keeping your "feet on the ground" would be wanted. You may want to look into what the US Department of Defense has done with their "Dismounted Soldier" project; their goals are kinda similar, wanting to train soldiers in varying terrain, etc.

As far as the Flostation is concerned, being in the chair was meant to simulate a gravity free environment. By supporting the body in the pose they designed (and in a chair that supposedly was very posh and comfortable - these things were handmade and very expensive), which like I said was a patented combination of the "zero gravity" pose and some pose for yoga - supposedly the outside world "went away" for the most part. This, coupled with the special display (essentially an XGA projector projected on the outside of the sphere the display; it was spherically warped by optics or software, such that inside the sphere, the back projected image was perceived as "flat", but it still surrounded your peripheral vision area - it was actually a pretty neat hack, giving the benefits of a large FOV HMD and monitor all in one, at a lower cost), and the motion platform system (yaw/pitch/roll mainly), along with other transducers (bass shakers) allowed for a very interesting experience.

The system originally was designed out of the guy's garage, then he got a NASA grant to expand it and use it for astronaut training; it didn't go much beyond the prototype phase (but the prototypes did tour the country to various conference venues).

I don't mean to say that it's not a bad idea, just not the same kind of immersion that I want.

Understood.

As for the hydralic/pneumatic system as well as the air muscle, I'd be afraid of what happens if something goes wrong. Hydralics don't give in all that easy, and if someone's not expecting it, a sudden jolt from the game engine could physically harm someone, which is NOT a good thing from a company's perspective. Lawsuits and such being what I mean.

A valid thing to think about; if such a thing is on your mind, then pneumatics running a low pressure (or being actuated by servos, instead of a pump system) would be best. Pneumatics have a springyness to them that would be more suited to the need. You could potentially do something with motors and gearboxes, but you would need to make sure that everything was either back-driveable and/or clutched, which would introduce more mechanical complexity. It might be possible to do something with cables and slip-clutched winch mechanisms attached to gear-motor servos...

I would need something that's soft as far as strength goes, but strong enough to make you feel that you're walking up a hill, rather then just walking forward.

Something you might also look into are 2 dimensional treadmills. Essentially they consist of two treadmills that overlap each other, and the belts are composed of many little rollers/wheels at perpendicular angles to the direction of travel. When you walk on them at an angle, the motion is translated via friction to cause both treadmills to move in proportion the vector sum of the direction being moved. You then allow for motors to backdrive the treadmill, and then mount the whole unit on a motion platform (to allow you to tilt it)...

Thanks for the suggestions though I appreciate it, and I intend on going forward with this still XD Just need to find the right motor/pressure system.

Good luck with the project; it won't be easy, but it will be rewarding (and if you have never been in a fully immersed virtual environment - you may be in for a treat!)...

:slight_smile:

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I haven't been in a fully immersive environment, but I have been in a partial via the Johnny Lee head tracking wiimote trick. One very interesting system for how simple it was.

And I also know of simulator sickness, there are people that even get it from playing regular games, but unfortunately, you can't force someone to stop using a system.

You did point out that this could be use for more then just regular gaming as well. I'm sure if it worked right, the military would be very happy, and maybe even some people that like to run and can't because they live in a cold environment or something like that can then. XD Who know what it could be used for, but that's all down the line. :stuck_out_tongue: I mainly want to build it just for personal use and just to see how it feels.