Hi Nicklas, it should be fine to keep the step rate (velocity) constant between updates from the trajectory planner, assuming that it runs at something like 1kHz and the machine is not highly dynamic. Limiting velocity and acceleration in the step generator should generally not hurt and avoids stalled motors in case there is a step in the position command (which should not happen with LinuxCNC unless you mess around with the signals in HAL).
If you want to implement smooth point-to-point positioning, you could consider some kind of jerk limiting, e.g. by using quadratic or cubic velocity profiles (giving linear or quadratic acceleration). Or use a sinusoidal profile, but trigo functions are computationally rather expensive. Regards, Philipp On 18.03.2016 21:15, Nicklas Karlsson wrote: > It could be a good option so I do not need to have a large computer for a > small machine. As is know it is more a question about how to ideally > increases/decrease step rate for a stepper motor? > > > > On Fri, 18 Mar 2016 16:05:31 -0400 > John Alexander Stewart <ivatt...@gmail.com> wrote: > >> Just FYI - about a year ago or so I purchased from Jeff @xylotex a BBBlack >> and DB-25 cape - ran my Unimat SL CNC'd lathe just fine (feeding a spare >> Gecko G540, 2 axes of which were unused) >> >> BBBoard from Xylotex came with LinuxCNC Machinekit on a little SDCard. An >> out of the box solution. >> >> >> >> On Fri, Mar 18, 2016 at 3:50 PM, John Dammeyer <jo...@autoartisans.com> >> wrote: >> >>> You might look at the Replicape and a BeagleBone Black. There are several >>> other capes including one with a standard DB-25 parallel port that run >>> LinuxCNC on the Beagle. Search for MachineKit. >>> >>> John >>> >>>> -----Original Message----- >>>> From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com] >>>> Sent: March-18-16 12:27 PM >>>> To: Enhanced Machine Controller (EMC) >>>> Subject: Re: [Emc-users] Stepper, ideal pulses without feedback >>>> >>>> >>>> Nice box and standard port is always good, I should think about it. >>> Steppers >>>> are for an xyz engraver so it is essentially a mini CNC machine without >>> tool >>>> changer. >>>> >>>> >>>> >>>> On Fri, 18 Mar 2016 12:00:55 -0700 >>>> "John Dammeyer" <jo...@autoartisans.com> wrote: >>>> >>>>> You are welcome to look at my Electronic Lead Screw Code. Follow the >>>> link >>>>> to the code. It's written for a PIC in C. >>>>> John >>>>> >>>>> >>>>> "ELS! Nothing else works as well for your Lathe" >>>>> Automation Artisans Inc. >>>>> http://www.autoartisans.com/ELS/ >>>>> Ph. 1 250 544 4950 >>>>> >>>>> >>>>> >>>>> >>>>>> -----Original Message----- >>>>>> From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com] >>>>>> Sent: March-18-16 11:46 AM >>>>>> To: emc-users@lists.sourceforge.net >>>>>> Subject: [Emc-users] Stepper, ideal pulses without feedback >>>>>> >>>>>> >>>>>> I am planning to use a micro controller for stepper step pulse >>> generation. >>>>> I >>>>>> have considered to use an inverter card but special purpose stepper >>>>> circuits >>>>>> are cheap so I use one of these instead. It should be possible to >>> feed >>>>> timer >>>>>> values then toggle should happen via DMA timer output compare values. >>>>>> >>>>>> Can anyone suggest how an ideal step generation curve should look? >>>>>> Constant acceleration up to top speed? Constant deceleration from top >>>>>> speed to zero? Or just stop generating pulses? >>>>>> >>>>>> Regards Nicklas Karlsson >>>>>> >>>>>> >>>>> >>> >>> ---------------------------------------------------------------------------- >>>>> -- >>>>>> Transform Data into Opportunity. >>>>>> Accelerate data analysis in your applications with >>>>>> Intel Data Analytics Acceleration Library. >>>>>> Click to learn more. >>>>>> http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 >>>>>> _______________________________________________ >>>>>> Emc-users mailing list >>>>>> Emc-users@lists.sourceforge.net >>>>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>>> >>>>> >>>>> >>> >>> ---------------------------------------------------------------------------- >>> -- >>>>> Transform Data into Opportunity. >>>>> Accelerate data analysis in your applications with >>>>> Intel Data Analytics Acceleration Library. >>>>> Click to learn more. >>>>> http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 >>>>> _______________________________________________ >>>>> Emc-users mailing list >>>>> Emc-users@lists.sourceforge.net >>>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>> >>>> >>> >>> ---------------------------------------------------------------------------- >>> -- >>>> Transform Data into Opportunity. >>>> Accelerate data analysis in your applications with >>>> Intel Data Analytics Acceleration Library. >>>> Click to learn more. >>>> http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 >>>> _______________________________________________ >>>> Emc-users mailing list >>>> Emc-users@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>> >>> >>> >>> ------------------------------------------------------------------------------ >>> Transform Data into Opportunity. >>> Accelerate data analysis in your applications with >>> Intel Data Analytics Acceleration Library. >>> Click to learn more. >>> http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 >>> _______________________________________________ >>> Emc-users mailing list >>> Emc-users@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/emc-users >>> >> ------------------------------------------------------------------------------ >> Transform Data into Opportunity. >> Accelerate data analysis in your applications with >> Intel Data Analytics Acceleration Library. >> Click to learn more. >> http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ > Transform Data into Opportunity. > Accelerate data analysis in your applications with > Intel Data Analytics Acceleration Library. > Click to learn more. > http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users >
signature.asc
Description: OpenPGP digital signature
------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140
_______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
