On Sun, 1 Dec 2013, Robert Ellenberg wrote: > Date: Sun, 1 Dec 2013 17:30:02 -0500 > From: Robert Ellenberg <[email protected]> > Reply-To: EMC developers <[email protected]> > To: EMC developers <[email protected]> > Subject: Re: [Emc-developers] Initial tests of circular arc blending > > Good find! After running that program, I'm seeing similar spikes. That > error is a subtle one, and I think I know what's causing it. There are rare > cases where a segment hits its target almost exactly, so the split time is > small or non-existent. All of the acceleration spikes in my logs correspond > to this case, so I need to take another look at what happens when we hit > the target exactly. > > As for possible realtime errors, my answer for now is to simply run the > loop slower until we can do some profiling and optimization. My code as > it's written now is a bit expensive to run a 5 or 10 kHz, but we shouldn't > need to run that fast unless you have a very fast and very accurate > machine. > > I've also been working on how to correlate desired accuracy and velocity to > the update rate. For example, if you want segments that are 0.001" long > with a peak velocity of 120ipm, then you need a ~12kHz update rate to be > able to hit every segment (with blend arcs) at that speed. This is of > course the worst-case scenario, as other limits such as cornering > acceleration and machine accuracy will be the limiting factors. > > -Rob >
Its good to remember that both step/dir systems and most servo systems are running in velocity mode (effectively linear extrapolation from each way point) so that the actual errors caused by a lower update rate are only second order errors. What I consider a fast CNC machine may machine at 600 IPM with 400 IPS/S acceleration (1/40 sec to full speed) Even with these extremes, its possible to keep within 1/5000" of a acceleration limited profile with 1 KHz position (and velocity) update rate. If the TP provided forward differences for velocity and higher derivatives a much slower update rate is feasible if the underlying hardware has a simple extrapolator. > > > On Sun, Dec 1, 2013 at 2:46 PM, sam sokolik <[email protected]> wrote: > >> ok - I still think there is an issue - maybe with really short line >> segments? this program causes a huge jump in position and accelleration.. >> >> http://pastebin.com/97YFUnsM >> >> (around line 1064) >> >> That is with strait G64. If I do a G64P.010 - it runs much further >> through the program - almost 3/4 or so before it fails >> >> (whole program) >> http://electronicsam.com/images/KandT/testing/stellabee1.ngc >> >> no realtime errors on any runs... >> sam >> >> >> >> On 12/01/2013 11:33 AM, sam sokolik wrote: >>> wow - more testing - so far - it looks like the constraint violations >>> are from the realtime issuses.. running 1khz on this computer is not >>> showing the errors I was seeing >>> >>> It really is quite awesome. The performance improvment over the current >>> tp is pretty substantial.. >>> >>> Still testing >>> sam >>> >>> >>> On 12/01/2013 10:45 AM, sam sokolik wrote: >>>> ok - those blends make sense (other than I don't know why they are >>>> parabolic) as those segments are longer.. >>>> >>>> sam >>>> On 12/01/2013 10:12 AM, sam sokolik wrote: >>>>> ok - a little more testing (just a little) >>>>> >>>>> I wonder if what I am seeing is caused by realtime errors.. I was >>>>> running 5khz thread which is on the edge on this computer. when I went >>>>> to 1khz it obeyed constraints.. >>>>> >>>>> There are a few blends(large) that look odd to me - you can see it here >>>>> >>>>> http://imagebin.org/279832 >>>>> >>>>> sam >>>>> >>>>> ps - if the previous failure was caused by missed realtime - I wonder >> if >>>>> that needs to be figured into things. (if a realtime target is missed >> - >>>>> the machine should not go wonky) >>>>> >>>>> sam >>>>> >>>>> >>>>> >>>>> >>>>> On 11/30/2013 04:52 PM, Robert Ellenberg wrote: >>>>>> I'm looking into it now, but I think it's an optimization issue. I'm >>>>>> exporting position, velocity, and acceleration data through sampler >> now, so >>>>>> it's easier to identify small blips in velocity. With smoothing >> enabled, >>>>>> there shouldn't be any significant blips in velocity on the spiral >> example. >>>>>> >>>>>> >>>>>> On Sat, Nov 30, 2013 at 5:24 PM, sam sokolik <[email protected]> >> wrote: >>>>>> >>>>>>> I pulled it yesterday. mid day or so.. I will try to get a halscope >>>>>>> tonight (and check to see if I have the latest git) >>>>>>> >>>>>>> what are your thoughts on the spiral velocity? >>>>>>> >>>>>>> sam >>>>>>> >>>>>>> >>>>>>> >>>>>>> On 11/30/2013 01:41 PM, Robert Ellenberg wrote: >>>>>>>> That's an interesting result. I just ran 3D Chips myself with my >> test >>>>>>>> config (tests/trajectory-planner/circular-arcs) and it didn't have >> that >>>>>>>> hiccup. However, I had an issue a few commits back that looked like >> that. >>>>>>>> It happened when a segment switched from parabolic blending to arc >>>>>>>> blending. I fixed it by adding the split-cycle check during >> parabolic >>>>>>>> blends, so that we shouldn't get to the end of a segment without >> knowing >>>>>>>> exactly when to stop. Are you running the latest code? I pushed an >> update >>>>>>>> recently, so that might make a difference. Also, could you upload a >>>>>>>> screenshot of the spiral code HAL scope? >>>>>>>> >>>>>>>> There's another possible cause: I found a possible error with one >> of my >>>>>>>> formulas in the tpCreateBlendArc at lines 768-774. It will be a >> simple >>>>>>> fix >>>>>>>> I think, so I should have updates by tonight. Thanks for the >> feedback! >>>>>>>> >>>>>>> >> ------------------------------------------------------------------------------ >>>>>>>> Rapidly troubleshoot problems before they affect your business. >> Most IT >>>>>>>> organizations don't have a clear picture of how application >> performance >>>>>>>> affects their revenue. With AppDynamics, you get 100% visibility >> into >>>>>>> your >>>>>>>> Java,.NET, & PHP application. Start your 15-day FREE TRIAL of >>>>>>> AppDynamics Pro! >>>>>>> >> http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk >>>>>>>> _______________________________________________ >>>>>>>> Emc-developers mailing list >>>>>>>> [email protected] >>>>>>>> https://lists.sourceforge.net/lists/listinfo/emc-developers >>>>>>>> >>>>>>> >> ------------------------------------------------------------------------------ >>>>>>> Rapidly troubleshoot problems before they affect your business. Most >> IT >>>>>>> organizations don't have a clear picture of how application >> performance >>>>>>> affects their revenue. With AppDynamics, you get 100% visibility >> into your >>>>>>> Java,.NET, & PHP application. Start your 15-day FREE TRIAL of >> AppDynamics >>>>>>> Pro! >>>>>>> >> http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk >>>>>>> _______________________________________________ >>>>>>> Emc-developers mailing list >>>>>>> [email protected] >>>>>>> https://lists.sourceforge.net/lists/listinfo/emc-developers >>>>>>> >>>>>> >> ------------------------------------------------------------------------------ >>>>>> Rapidly troubleshoot problems before they affect your business. Most >> IT >>>>>> organizations don't have a clear picture of how application >> performance >>>>>> affects their revenue. With AppDynamics, you get 100% visibility into >> your >>>>>> Java,.NET, & PHP application. Start your 15-day FREE TRIAL of >> AppDynamics Pro! >>>>>> >> http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk >>>>>> _______________________________________________ >>>>>> Emc-developers mailing list >>>>>> [email protected] >>>>>> https://lists.sourceforge.net/lists/listinfo/emc-developers >>>>>> >>>>> >> ------------------------------------------------------------------------------ >>>>> Rapidly troubleshoot problems before they affect your business. Most IT >>>>> organizations don't have a clear picture of how application performance >>>>> affects their revenue. With AppDynamics, you get 100% visibility into >> your >>>>> Java,.NET, & PHP application. Start your 15-day FREE TRIAL of >> AppDynamics Pro! >>>>> >> http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk >>>>> _______________________________________________ >>>>> Emc-developers mailing list >>>>> [email protected] >>>>> https://lists.sourceforge.net/lists/listinfo/emc-developers >>>>> >>>> >> ------------------------------------------------------------------------------ >>>> Rapidly troubleshoot problems before they affect your business. Most IT >>>> organizations don't have a clear picture of how application performance >>>> affects their revenue. With AppDynamics, you get 100% visibility into >> your >>>> Java,.NET, & PHP application. Start your 15-day FREE TRIAL of >> AppDynamics Pro! >>>> >> http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk >>>> _______________________________________________ >>>> Emc-developers mailing list >>>> [email protected] >>>> https://lists.sourceforge.net/lists/listinfo/emc-developers >>>> >>> >>> >> ------------------------------------------------------------------------------ >>> Rapidly troubleshoot problems before they affect your business. Most IT >>> organizations don't have a clear picture of how application performance >>> affects their revenue. With AppDynamics, you get 100% visibility into >> your >>> Java,.NET, & PHP application. Start your 15-day FREE TRIAL of >> AppDynamics Pro! >>> >> http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk >>> _______________________________________________ >>> Emc-developers mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/emc-developers >>> >> >> >> >> ------------------------------------------------------------------------------ >> Rapidly troubleshoot problems before they affect your business. Most IT >> organizations don't have a clear picture of how application performance >> affects their revenue. With AppDynamics, you get 100% visibility into your >> Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics >> Pro! >> http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk >> _______________________________________________ >> Emc-developers mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-developers >> > ------------------------------------------------------------------------------ > Rapidly troubleshoot problems before they affect your business. Most IT > organizations don't have a clear picture of how application performance > affects their revenue. With AppDynamics, you get 100% visibility into your > Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! > http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
