Ok, so I have an idea that I want to throw out there, but I'm not sure how practical it is. I was thinking of how to create something like a pair of gloves for use in a 3d environment. Now I obviously don't mean the real world, but virtually, like in a game. My basic idea originally was to have some form of spring loaded potentiometer for each finger. This means it'd turn all the way on when a fist is made and all the way off when fingers are open wide. Attach a string on the potentiometer, attach the other end to the finger tip, and have rails or a sleeve that keeps the string on each finger. As you bend your fingers, you pull on the potentiometer making the values increase/decrease.
While this is a sound way of doing it, it also doesn't give any feedback. Sure, you could have a vibrating motor to let you know you are holding something, but it wouldn't work as far as making you feel like you've grabbed something. My current idea is to have something like a small servo motor to pull on the string when the 3d engine finds you've "grabbed" something.
With all that explanation, I guess what I'm wanting to know is, is there something that works like a servo (not strong enough to hurt anyway) that also can double as a sensor (reading being pulled on or released)??
If not, I'm sure I could just use a combination of a weak servo with a custom built spring pot system, but that's extra work and inputs/outputs, so I'd rather have it all in one. Any ideas?
(This is all an in my head project at the moment, but It'd be cool to work on it when I get some extra cash on hand.)
You might want to take a look into what has been explored over the past 25+ years in haptic glove interfaces.
For what it's worth, you probably won't find anything off the shelf to do what you want; instead, you are going to need to build something.
One method that has been explored is to line the fingers on the palm side with inflatable bladders (you could use latex tubing or balloons, for instance), and inflate those with compressed air (from a pump or tank/cylinder), which you control using solenoid valves. This would give you the pressure feedback you desire.
For detecting the flexing of the fingers, you could use flex sensors, like were used in the old Nintendo Powerglove. You don't need to tear one of these apart anymore (in fact, they are rapidly becoming collector's items, and are starting to become difficult to find - as well as being expensive to buy). Instead, several companies sell the sensors - look for "resistive flex sensor" and similar.
When you bend the sensor, it changes resistance - very easy to interface with the Arduino.
Just note that you are going to end up with a fairly bulky glove in the end (no real way around that). Also note that whatever kind of sensor or haptic device you put on the glove and fingers, the fabric -will- shift, causing the reading and such to change. This has always been a major headache for glove devices used in virtual reality simulations and such.
If you wanted to go a bit "higher tech" - you could try to build your own "VPL DataGlove" system using fiber optics and IR LEDs and photo-transistors; I leave it to you to figure out the details (more than enough info out there if you want to give it a try - heck, I have an old article I wrote a long time ago up on my website about building an optical flex sensor glove on the cheap).