Like many universities, EPFL has an innovation park for start-up companies: there I visited Force Dimension, a company that has exploited the delta robot invented by Reymond Clavel to create a haptic device. In this kind of system you don't expect your hand to explore a system directly (as with the virtual reality workstation I mentioned previously). Instead, your interaction with the virtual world is mediated through some kind of instrument. For instance, in the image on the right, you can think of the black sphere I'm holding as the handle of some kind of short, fairly blunt, tool. I can use this to probe the virtual landscape. If I hit a solid object, I will feel force feedback from the robot arm. The system also creates vibrations that allow me to feel textures and friction as I move around.
Using the Force Dimension device was a lot of fun, and pretty realistic: the forces imparted were very large. The experience reminded me of when, at MIT, I got to feel the one of the very early Phantom devices invented by Thomas Massie (a modern version is shown left, but the device I remember looked much the same). At the point that I got to use the system, maybe 1993 or 1994, he'd just recently set up SensAble Technologies: a company that has has since become very successful. Force Dimension claims that the force that their device imparts is much greater than the Phantom, but I couldn't possibly compare after more than a decade.
Anyway, I can remember being very impressed trying Massie's device, which was a memorable experience in more ways than one. Not only was it the first haptic device I ever tried but, with the early prototype I used, there seemed no special protocol for starting a session. I put my finger inside a thimble (the tool through which I would feel the virtual world), and they ran the program. Apparently, because of the position at which my hand happened to be, I 'materialized' into the virtual world deep inside a solid object. Because of this, the force-feedback response was to use every Newton available to push me out of there, pretty much instantly. After my getting over this shock (it was pretty violent!) and Thomas resetting the system, I very much enjoyed using it to feel objects and textures.
Nothing's perfect, but both of these devices are pretty impressive. I only wish they were not so bulky.
Finally, before I get off this subject for a while, I wanted to say that probably the most impressive haptic device I've ever used was designed by Allison Okamura of Johns Hopkins University. One of her goals is to develop systems that allow surgeons to either practice surgery or to allow them to teleoperate while getting good sensory feedback. So she designed some haptic scissors (right) for doing what surgeons do: cut. When I used this device, I got the chance to feel what it was like cutting through skin and organs and blood vessels. It was extremely realistic, and the fact that the tool was not just probing but really interacting with the virtual world made it particularly compelling. Again, the system works entirely through vibration and force feedback.
Top: Me trying a Force Dimension haptic device.
Middle: A current model of the Phantom device from SensAble Technologies.
Bottom: Allison Okamura with her haptic scissors for telesurgery and surgical simulation.