klw11037@uxa.cso.uiuc.edu (08/18/90)
Some time back, there was a note discussing feedback in data gloves and data suits. Along the line of data gloves, does anyone know of work being done with electro-rheologic fluids as part of a feedback system? There has been some interest in them for various mechanical systems of late, and they might be useable to provide a controllable viscous damping form of feedback. I fully admit that I know very little about electro-rheologics. If that were possible, then combining that with a set of several nitinol wires running down the front and back of the fingers with a critical temperature set several degrees above body temp and acting as electrically controlled springs would seem to be a way to simulate the resistance of various objects to being grasped. An array of several of the wires along each finger would allow a varied response to movement that could increase spring force as the deflection of the finger increased, in the case of say a rubber ball, or, as in the case of crushing a paper cup, increasing back pressure up to a yield point and then partial release. Nitinol can generate a fair bit of force when returning to it's initial shape, and reacts quite quickly to temperature over it's critical temperature, especially in a thin wire. The cool down time to go back below the the critical temperature might be a problem, I don't know whether it would be fast enough. Comments? If I'm talking nonsense, then please let me know:-). Kyle Webb
auric2@hardy.u.washington.edu (Eric Vondergeest) (08/21/90)
In article <138900001@uxa.cso.uiuc.edu> klw11037@uxa.cso.uiuc.edu writes: >Some time back, there was a note discussing feedback in data gloves and >data suits. Along the line of data gloves, does anyone know of work being >done with electro-rheologic fluids as part of a feedback system? There has > >Kyle Webb I thought part of the problem with force-feedback was concern for the safety of the user. Mechanical devices are bulky and could possibly pinch the user in undesirable ways, and the fluids you speak of intro- duce the problem of more electricity that could possibly shock the user. What interested me was a report of some sort of gelatinous substance that contracted in the presence of visible light, reported in the Wall Street Journal on or around 8/17/90. Would it be feasible to construct an exo-muscular system into a data glove or a body suit?
klw11037@uxa.cso.uiuc.edu (08/24/90)
Was there anything in the article on the percentage of total length that it contracted and the amount of force that it could exert? Was the light the only power source, or was there another source with light simply the trigger? Speed of response would be another factor. True that user safety is a major concern. The problem is to exert enough force to stop a preempted motion (e.g. squashing a construct that is representing a steel bar) but not being able to apply the force in such a way as to injure or stop desired movement. My idea with the combination of nitinol springs and variable viscous damping was that the spring system could be made weak enough that it would be strong enough to halt motion with the viscous damping turned on, but not by itself. I don't know about the voltages involved in controlling electro-rheologics. I'll try to find out. Kyle Webb