Thanks for your responses Kirk and Andy! No, we are not planning to create a toy here and the machine wants to be production oriented, as that is what pays for it! There will have to be further mechanical improvements as to avoid that the Sleds could jump a tooth on their linear gears, but the servo eliminates the potentially missed step of a stepper at any speed. The wish to close the loop could be interesting to be able to recognize obstacles (current limit) or adjust speeds to machine physics without having to manually calibrate. But its true if this is not yet implemented, I cant promise to be the one to do it ;)
So now I understand that if using the gecko driver I would have to also feed the motion readout to the computer somehow in order to close the loop? Then I think it would be better to go to some other type of interface that can do that in one move! Anybody using these FPGA based controller cards here? Or the pico solution, what do they do? Also, i know I have to call them but maybe somebody has experience for these servo motors: *KL23-130-60 (NEMA23) dual Shaft $79.95 Skewed Rotor * http://www.kelinginc.net/ServoMotors.html Do i need to get the readout encoder or does it come with it? I see no specification what kind of signal this provides! Skewed rotor refers to the little twist in the laminate stack? I suppose this would be a brushed DC motor? Brush-less I bet is much more expensive? Thanks you guys for working with me, we are hoping to make a purchase this week! On Wed, Aug 10, 2011 at 1:28 PM, Kirk Wallace <[email protected]>wrote: > On Wed, 2011-08-10 at 12:25 -0700, Tobias Gogolin wrote: > > No problem if the servo solution is a bit more expensive than the > steppers, > > i do believe that i's the way to go for a more agile and useful machine! > > There are basically two rates to consider. One is cutting feed rate and > is mostly determined by the workpiece material, cutter type, machine > rigidity, etcetera. This rate is usually considered slow. Then there is > rapid, which is the fastest rate the machine can move without gross > position errors and is used to get the axes to and from home, the > workpiece or the tool changer. If the application is a hobby machine, > rapids are not usually important, so one can gear reduce the axes to get > higher torque. Rapids become important in manufacturing when > part-to-part time can cut into the profit margin. > > > I need to understand a bit more about what means EMC has to 'close the > loop'. > > I suspect a motor current readout would help to see how hard the driver > has > > to try to achieve the required position? > > One can get an idea of the load by using HALscope or HALmeter to watch > the following error. This difference between the requested position and > the current position is part of the feedback loop that EMC2 uses to > compute the next output command. Geckos and similar step/dir input servo > drivers have this loop intelegence built in. I prefer to use EMC2's loop > because it allows the integrator to configure and customize the loop, > and use HALscope and HALmeter. > > > Funny I also found the same http://www.geckodrive.com/g320x-p-28.htmland > > was studying its specifications, but i couldn't find a way this one would > > close the loop! > > As above, the loop is inside the Gecko. One could run the encoder data > to both the Gecko and EMC2, but this is more advanced than I can comment > on. > > > You say that it could be simply connected to 2 lines of a parallel port? > > Even from the manual I can't find any evidence that the Gecko driver > could > > be used for closed loop operation! > > The standard way to do this is to set EMC2 similar to a stepper system > so that it outputs step and direction, then set up EMC2 .ini file > parameters to known safe parameters. I don't know if Gecko servoe drives > have a fault output, but if so, this could be linked into EMC2. > > > Are there any better solutions? I suppose for pico or the FPGA controller > > (which I like for its potential to do very quick responses processed > > locally) I'll have to consult with their application engineering? > > The FPGA solutions from Pico, Mesa, Pluto-P are fairly well developed, > so their documentation should be enough to get one through a standard > installation. An FPGA is basically used to receive a velocity or > position command from EMC2 (through the printer port or PCI slot) and > turn it into a high speed PWM signal that would then go to a PWM input > servo amplifier. The printer port could also be used to create PWM > signals, but the printer port is considered fairly slow. My Shizuoka > uses the the printer port (software) signal generator: > http://www.wallacecompany.com/machine_shop/Shizuoka/ > > which works fine for stepper phase generation (or step/dir signals). > Software PWM generation is only good for playing in the lab, but can be > very informative. > > > -- > Kirk Wallace > http://www.wallacecompany.com/machine_shop/ > http://www.wallacecompany.com/E45/index.html > California, USA > > > > ------------------------------------------------------------------------------ > uberSVN's rich system and user administration capabilities and model > configuration take the hassle out of deploying and managing Subversion and > the tools developers use with it. Learn more about uberSVN and get a free > download at: http://p.sf.net/sfu/wandisco-dev2dev > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Tobias Gogolin Tel. Movistar (646) 124 32 82 Tel. Telcel (646) 160 58 99 skype: moontogo messenger: [email protected] First Bitcoin Account: 1LCupcVd8HhAGyVhd3xayPpnQHeis7rAiV Blog: http://zeitgeistensenada.blogspot.com/ You develop Sustainable Ranch Technology at http://tech.groups.yahoo.com/group/SURA-TECH an Open Source Electric Motor/Alternator at http://groups.yahoo.com/group/Performance_Axial_Flux and an Open Source Motor Controller at http://groups.yahoo.com/group/GoBox ------------------------------------------------------------------------------ Get a FREE DOWNLOAD! and learn more about uberSVN rich system, user administration capabilities and model configuration. Take the hassle out of deploying and managing Subversion and the tools developers use with it. http://p.sf.net/sfu/wandisco-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
