I also suspect max acceleration will be a little bit lower for higher speed since motor back-emf will limit available voltage for acceleration.
On Fri, 28 Aug 2015 01:47:23 +0000 Kyle Kerr <ker...@gmail.com> wrote: > Late to the party armed with nothing more than book smarts, may not be > enough. > If you can accurately measure time over distance, you should be able to > find relatively close max accel. Once the time over distance is constant > from point to point you go back and say 0 to 100 took 500mS and 14mm or > whatever. Then you just do the math to find acceleration. > > On Thu, Aug 27, 2015, 6:47 PM Dave Cole <linuxcncro...@gmail.com> wrote: > > > >>>If you set the max acceleration lower than > > the actuator is capable of, I assume it will work fine and just take longer > > to ramp up to full speed than it could in theory.<< > > > > Yes. It will work fine. You want the accel limit lower than less that > > what it can actually do. Years after you set this up and things get a > > little gummed up, > > you don't want your actuator to be slower than what you command. That > > may result in following errors and frustration. > > > > The same is true of the max velocity. > > > > Dave > > > > > > > > On 8/27/2015 6:15 PM, Jerry Scharf wrote: > > > My question was the opposite. If you set the max acceleration lower than > > > the actuator is capable of, I assume it will work fine and just take > > longer > > > to ramp up to full speed than it could in theory. > > > > > > jerry > > > > > > On Thu, Aug 27, 2015 at 1:50 PM, Karlsson & Wang < > > > nicklas.karls...@karlssonwang.se> wrote: > > > > > >> If you try to accelerate the actuator above what the actuator is capable > > >> of the best thing that could happen is it will not keep track of the > > >> position and the other thing are more bad. > > >> > > >> > > >> > > >> > > >> On Thu, 27 Aug 2015 11:35:04 -0700 > > >> Jerry Scharf <jsch...@finsix.com> wrote: > > >> > > >>> Hi, > > >>> > > >>> One last question about this. Is there any harm in reducing the max > > >>> acceleration below what the actuator is capable of? I wouldn't seem > > like > > >>> it, but I want to be sure. > > >>> > > >>> I know it will slow things down a bit, but this is by far the fastest > > >> part > > >>> of my system and only moving a short distance. > > >>> > > >>> jerry > > >>> > > >>> > > >>> On Tue, Aug 25, 2015 at 5:04 PM, TJoseph Powderly <tjt...@gmail.com> > > >> wrote: > > >>>> Jerry I didnt answer your question. > > >>>> to measure acceleration there's an industry standard 'step' test. > > >>>> The 'step' is to apply the voltage required to achieve max velocity. > > >>>> This voltage **instantly** rises from 0 to the value needed for max > > >>>> velocity. > > >>>> Thats where the name 'step' comes from, > > >>>> Its a square edge on a scope. > > >>>> > > >>>> A second measurement is now needed, > > >>>> Some way to determine _when_ the > > >>>> maximum velocity is actually achieved. > > >>>> > > >>>> Old school dc motors gave us Tachos so this was easy. > > >>>> I dont know what you can put together. > > >>>> You could attach a voice coil to the end, I suppose. > > >>>> Measure when the output voltage goes constant ( at max vel ) > > >>>> A scope should show a 'knee' starting at 0Volts. > > >>>> > > >>>> But if you measure time from the 'step' until the max vel, > > >>>> you have the precise acceleration _time_. > > >>>> > > >>>> The acceleration time divide by time is the acceleration > > >>>> > > >>>> ( example .240 Sec accel time to achieve 800mm/minute velocity > > >>>> is .24 sec to achieve 13.333mm/sec > > >>>> is 55.555 mm/s/s > > >>>> > > >>>> 3.15"/sec / 0.02ec = 157.5in/s/s ) > > >>>> > > >>>> HTH > > >>>> TomP > > >>>> tjtr33 > > >>>> On 08/25/2015 04:09 PM, Jerry Scharf wrote: > > >>>>> Hi, > > >>>>> > > >>>>> My quick scan of the docs didn't find an explanation for how to > > >> calculate > > >>>>> this from manufacturer specs rather than experimentation. I want to > > >> make > > >>>>> sure I am doing this right. > > >>>>> > > >>>>> The actuator is rated a 3.15 inches per second and it can reach full > > >>>> speed > > >>>>> in under .02s for the load I will be putting on it. If I use a = v/t, > > >>>> this > > >>>>> comes out to about 150 inches per second square. Does this look > > >> right? > > >>>>> The actuator is a SMC LXPB2BD-50S that I picked up used. > > >>>>> > > >>>>> jerry > > >>>>> > > >>>> > > >>>> > > >>>> > > >> > > ------------------------------------------------------------------------------ > > >>>> _______________________________________________ > > >>>> Emc-users mailing list > > >>>> Emc-users@lists.sourceforge.net > > >>>> https://lists.sourceforge.net/lists/listinfo/emc-users > > >>>> > > >>> > > >>> > > >>> -- > > >>> Jerry Scharf > > >>> FINsix IT > > >>> 650.285.6361 w > > >>> 650.279.7017 m > > >>> > > >> > > ------------------------------------------------------------------------------ > > >>> _______________________________________________ > > >>> Emc-users mailing list > > >>> Emc-users@lists.sourceforge.net > > >>> https://lists.sourceforge.net/lists/listinfo/emc-users > > >> > > >> > > ------------------------------------------------------------------------------ > > >> _______________________________________________ > > >> Emc-users mailing list > > >> Emc-users@lists.sourceforge.net > > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > >> > > > > > > > > > > --- > > This email has been checked for viruses by Avast antivirus software. > > https://www.avast.com/antivirus > > > > > > > > ------------------------------------------------------------------------------ > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
