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 ;) > > Regards, > Kent > > > > ------------------------------------------------------------------------------ > 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 ------------------------------------------------------------------------------ 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
