cdshaw@cs.UAlberta.CA (Chris Shaw) (02/28/91)
In article <17290@milton.u.washington.edu> Richard M Willis writes: >I have finished an interface box (8031 microcontroller, oscillators, etc.) >to control the firing of the ultrasonic transmitters on the Glove. ... > >Everything works fine, EXCEPT that the distances that I get are very noisy: >variation of 200 microseconds (about six inches) at a distance of five feet. This is a problem inherent in the technology. Accuracy is very low at anything but very short distances. You're probably going to have to get into some heavy filtering to make the numbers look better. I have heard of systems that can deliver +- 2 inch in a 20x20x20 foot measured space, but it's not deliverable at $100 per unit. (I'm being vague here.. better than 6 inches at 5 feet, but I forget how much better.) After all, if this technology delivered +- 0.25 inches RMS at 60 inches range, you'd have a $100 Polhemus Isotrak replacement at 1/30th the cost! -- Chris Shaw University of Alberta cdshaw@cs.UAlberta.ca Now with new, minty Internet flavour! CatchPhrase: Bogus as HELL !
dwillis@athena.mit.edu (Richard M Willis) (02/28/91)
I have finished an interface box (8031 microcontroller, oscillators, etc.) to control the firing of the ultrasonic transmitters on the Glove. The signals from the receiver array are passed through the junction box, which has level-testing op-amps that convert the oscillating waveform into a TTL-compatible gate signal. I am using a counter onboard the 8031 to determine the time-of-flight of the signal. Everything works fine, EXCEPT that the distances that I get are very noisy: variation of 200 microseconds (about six inches) at a distance of five feet. Question: Does anyone else have this problem ? I haven't seen much on the net about the Glove lately.