I don't like to believe that that is the best 'servo' conversion one could make adding a readout, one that would try faster pulses and lock... So if I can work with these motors, who can recommend a good high voltage power supply and microstepping driver for these?
Nobody has ever implemented a closed loop stepper controller in EMC? Thanks guys! On Tue, Aug 9, 2011 at 12:11 AM, gene heskett <[email protected]> wrote: > On Tuesday, August 09, 2011 02:33:30 AM Tobias Gogolin did opine: > > > Thanks cogoman and Roland for replying, yes indeed that is a quite > > important explanation why they use such a ridicoluously low voltage > > high curent motor (even though they use very thin wires) > > Torchmate kit came with a 5V 7A motor with 6 wires each! I wonder what > > kind of circuit model uses 6 wires? > > That is a unipolar motor where normally the motor supply voltage is > connected to a center tap on each winding, and transistors are connected to > the end wires. They are turned on to ground, but never at the same time. > > > How many phases might this motor have? > > The usual 2. > > > Also just thinking about it now, isn't the real concern the positive > > capability to move the sleds to the position and never to miss a step? > > Yes. > > > What if I rather focused on the smart move to close the loop (put a > > digital readout on each motor) and this way make sure that i only go as > > fast as i can positively accelerate the sleds??? > > Unforch, generally this is made difficult by the fact that if the motor is > being told to move faster than it can and slips a step, which will be > detected, but the correction applied is to supply the step signals at an > even faster rate. Generally the motor stalls. :( You have to reach back > into the trajectory planner and slow the whole machine before issuing the > corrective step(s) to that motor, thereby keeping the rest of the machine > from exceeding the allowable error and stopping everything with a 'joint > error'. It may have been done, but tuning such a setup can reduce ones > hair follicle count. Drastically. > > I found in my small machine, that the MAXVEL's could be doubled by > restricting the accelerations so they were rather leisurely. Mine carves > about as much wood as it does metal, using a die grinder as a 2nd spindle > to carve both the mortise and the tenon of a furniture joint. The aux > spindle is offset to the left and forward of the normal spindle so that the > stick getting a tenon carved on its end, clears the front of the table and > can hang clear to the floor in a fixture clamp I made. > > So the fix is to never accelerate faster than the motor can move under > load. Resonance dampers on the motors can also help quite a bit, and you > will see many, usually home made versions of those as you tour the web and > you tube looking at other machines, they are hanging on the motors rear > shaft. > > Similar remarks also favor 'microstepping' as this smooths the motors > motions by regulating the currents such that a 200 step/rev motor becomes a > 400-800-1600 (or more) step motor. I am currently using 8 microsteps, but > I have new drivers on a rowboat from Hong Kong that claim they can do 64 > steps. That may well be overkill, but it will be fun checking. And much > quieter in operation. > > [...] > > Cheers, gene > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > Outside of a dog, a book is a man's best friend. Inside a dog it's too > dark to read. > -- Groucho Marx > > > ------------------------------------------------------------------------------ > 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 ------------------------------------------------------------------------------ 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
