On May 6 2013 10:50 PM, Michael Haberler wrote: > Kent, Ebo, > > Am 07.05.2013 um 02:59 schrieb Kent A. Reed > <[email protected]>: > >> On 5/6/2013 5:00 PM, EBo wrote: >>> does anyone remember the paper that was posted to the group that >>> measured the loss in torque as a function of speed and jitter? >>> That >>> might give us a more principled start to develop guidelines. As a >>> note, >>> when you get anywhere close to the jitter threshold the apparent >>> acceleration/deceleration is greater than what the motor can >>> handle. >>> >>> hope that helps. >>> >>> >> >> Ebo: >> >> You may be thinking of this 2001 SPIE paper: >> >> Frederick M. Proctor and William P. Shackleford, "Real-time >> Operating >> System Timing Jitter and its Impact on Motor Control", Proceedings >> of >> the SPIE Sensors and Controls for Intelligent Manufacturing II, Vol. >> 4563, pp. 10-16, October 28, 2001. >> >> Nevermind the SPIE paywall. NIST provides a pdf copy at >> http://www.nist.gov/customcf/get_pdf.cfm?pub_id=824455 >> >> This is the work I alluded to in my earlier email. > > > I think it would be a very useful study topic (and a paper worth > publishing) to start with this work, and go a step further > > a sketch for the work based on the above I would find interesting in > general and very relevant to the discussions here: > > - the question I would care about is 'what is the incidence to loose > steps, given a certain load, and a certain noise distribution in the > stepping signal' > - start by measuring actual noise (latency profiles) of currently > used RT OSes, including a vanilla kernel > - create a signal generator can load and regenerate noise profiles > (better not based on linuxcnc but hardware, say a microcontroller) > - create a setup of stepper motor(s), a hires encoder, and a DC motor > with a controllable load (eg switchable shunt resistors or somesuch) > - come up with a way to detect lost steps based on input signal and > encoder signal > - automatically run various speed, noise and load profiles and > qualify them by 'lost steps' incidence > > I think the result of such a study could provide fact-based answers > to what latency in a soft-stepper context actually means, and that be > very valuable > > Note this does _not_ address the (IMO more interesting) question how > latency impacts 'path tracking quality' of a real and complete > motion/pid etc servo setup; that would be worth a separate attempt, > probably more based on control theory than measurements plus some > verification > > no junior researchers out here itching to publish? > > - Michael > > ps: on the question of shunt resistors - Amit's company might have > some scalable answers here, but Amit better explain their business > himself ;)
publishing? What is the target journal or outlet. Maybe one of the academics can convince a student to take it on. It would take a lot to really make this publishable in a peer reviewed journal/conference. EBo -- ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. This 200-page book is written by three acclaimed leaders in the field. The early access version is available now. Download your free book today! http://p.sf.net/sfu/neotech_d2d_may _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
