Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!apple!well!nagle From: nagle@well.sf.ca.us (John Nagle) Newsgroups: comp.robotics Subject: Re: 6 DOF Joysticks Message-ID: <22058@well.sf.ca.us> Date: 8 Dec 90 20:50:50 GMT References: <18232@hydra.gatech.EDU> <1990Dec6.232210.2638@sctc.com> <4282@media-lab.MEDIA.MIT.EDU> Distribution: na Lines: 18 minsky@media-lab.MEDIA.MIT.EDU (Marvin Minsky) writes: >Consider that the internal sensor-brain-muscle roudtrip time of a >human is of the order of 1/5 second -- so that when your brain tries >to do anythig in the outer world, you have a delay time of this order. Eye-hand control loops are of that order, but many purely tactile control loops in the body are much faster. The grasping reflex, which maintains finger contact forces at a level sufficient to prevent slip, operates in about 20ms. Flight simulator designers have discovered that update rates as high as 500Hz are required to make control forces "feel right". ("Flight Simulation", Rolfe and Staples, Cambridge University Press, 1986, section 4.10). A 1 sec delay in a tactile control loop thus represents roughly a 2 order of magnitude performance degradation. John Nagle