Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!uakari.primate.wisc.edu!dali.cs.montana.edu!milton!chris@ug.cs.dal.ca From: chris@ug.cs.dal.ca (Chris Robertson) Newsgroups: sci.virtual-worlds Subject: Re: Cheap Force Feedback for VR? Message-ID: <13542@milton.u.washington.edu> Date: 28 Dec 90 20:23:58 GMT References: <12079@milton.u.washington.edu> <13407@milton.u.washington.edu> <199 Sender: hlab@milton.u.washington.edu Organization: Chaos in my head, Halifax, NS, Canada Lines: 54 Approved: cyberoid@milton.u.washington.edu hermann@fsc.cpsc.ucalgary.ca (Michael Hermann) writes: > james@TWG.COM (James Marshall) writes >> Is there some kind of piezoelectric (?) material that rapidly >> expands when a voltage is applied to it? > There is a class of fluid compounds, whose name eludes me. These are normally > fluid, until a current is run through them, at which point they form a sort > of crystalline structure, and become much more solid. A family of compunds, specifically a class of liquid crystals, behaves this way, especially in gel form. For most such substances, however, the property does not endure well after repeated electrical agitation. > I believe one or more of the US auto manufacturers was looking into using > this goo as integral to reactive suspension systems. This is a different goo. I saw it in C&D a while back .. apparently some kind of electrically active colloidal suspension. Ever dump a wad of cornstarch in water? It has very low viscosity, acts like a liquid. But punch it, and no splash .. it temporarily solidifies (to a degree) on impact. Ball point ink is the same in reverse. They're also using this stuff for a continuous transmission .. infinitely many gears .. ;^) > As for a Dataglove application, the fluid could fill a number of small > bladders distributed about the digits, on the back and palms of the glove, > and around the wrist. Electrodes run to the bladders. Of course, use in a VR > application would require that the fluid have a boundary zone before it > turns solid, for graduations in force-feedback ... Yes, boundary zone. Big problem. Without precise amounts of just the right catalysts, temperature, etc., it seems very much a threshold event. This was several years ago i read about this stuff, and nothing since .. maybe they couldnt get it to work .. Also, think about this jello glove for a sec .. you wanna give the sensation of pressure in the middle of the palm, so you apply some juice, which presumably expands the gel-pocket, or whatever, and pressure is felt, right? But the gel-pocket is pushing OUT as much as IN, which is only counter- acted by the pull of the glove fabric on the BACK of the hand and .. hey wait a sec, why not just wrap a blood_pressure bag around that hand .. hmm. Somehow i cant see getting any tactile resolution out of this at all .. Smaller areas, like the fingers, where the glove can be tighter, and the gel-packs smaller, might prove to be a bit more effective .. perhaps the somewhat-sensation of holding something, i dunno .. No sig its late.