I am working on a project which uses a force feedback joystick. EMaze You must navigate a maze blind folded, so essentially you are moving around by feel rather than sight. **Instead of making the user require a blindfold (dont want to make them do anything), I was thinking of just decreasing the ambient light. The ground will be comprised of different textures, which will have different feels to them (different frictions. There will be ramps scattered around the maze (ramp forces). I am looking for a way to indicate to the user (via force feedback) that you have hit a wall. The first thing that popped into my head was to simply shake the stick in a random fashion, though that would not feel like you hit a wall (well unless you were running full tilt)... I am also looking for other ideas as to how to incorporate the other conditions/forces: inertia, damping, springs and so forth.

Make the thingie move in the direction that is the oposite of the direction that the wall. I dunno how force feedback thingies work tought, so I don't even know if you can make it move in a specific direction or just random.

If you have constant feedback from walking on various surfaces, the simple cessation of that feedback could let a player know they've stopped. Maybe some kind of "reach" command that would reach out and feel the object in front of you could work. If you reach out and feel a wall, you'll get one reaction. If you feel a door, it might feel different. That way, they can not only detect that they've hit something, but get an idea of what it is.

If I'm blindfolded, I'll be using sound as much as feel, so that should be an option.

If you're just doing a hardware demo, though, I can understand the desire to focus entirely on the hardware's capabilities.

First of all, if you are going to have several different texture "feels", then you will need to be certain to have a very distinct feel and sound for your wall(s); as this type of game may prove to be surprisingly difficult to play already. Second, there is the problem of "drag" for lack of a better word, meaning that you will probably need to experiment with different levels of vibrations in order to indicate to the player whether they have hit the wall dead on or at an angle, and whether or not they are still dragging against the wall or have gotten back on path.
If my guess is correct, this type of game would require a level of sensitivity to feel that the average audience just wouldn't have. So I would highly recommend keeping the ground texture vibrations to soft minimum. Perhaps texture sounds will help with separating these sensations as well. Last of all, personally, I like a more realistic feel when gaming so I would recommend a sudden, small and moderately intense burst of vibration and then "stop" for a dead on wall impact. And, maybe similar vibrations for the wall drags (assuming that you will have those). Hope I've been some help :) or atleast sparked some ideas.