A fast control loop that drives each motor at a given speed and a second slower control loop that figures out what that speed should be. The second loop typically uses "PID" even if only in fact the "P" is used.
That can be used to drive any number of motors all at their correct speeds. On Mon, Jul 13, 2020 at 7:28 PM R C <cjv...@gmail.com> wrote: > Interesting, > > > but I already have the motors, and the gears are on their way. What > I was really looking for is how to drive the stepper-drivers, he DM542 > series ones. > > > Ron > > > > On 7/13/20 7:53 PM, cogoman via Emc-users wrote: > > I recently discovered geared stepper motors. > > > > > http://www.zyltech.com/nema-17-stepper-motor-geared-planetary-gearbox-1-7-a-3-1-nm-435-ozin/ > > > > > > I've been happy with zyltech in the past. I bought one of these for > > evluation, but the specs seem to be great for CNC. Low enough current > > to work with a stepstick, High enough torque for a fairly powerful > > machine, and less than 4 mH inductance should let it step pretty fast. > > > > 5.18:1 gear ratio should reduce that 4 meter spur gear, but the link > > below has higher gear ratios that would reduce that spur gear greatly! > > Backlash could be a problem for CNC, but if you are only going one > > way, the less precision gearboxes might be fine. > > > > > https://www.omc-stepperonline.com/geared-stepper-motor/?sort=p.price&order=ASC > > > > > > Once you visit the stepperonline web page you know as much about them > > as I do, but their offerings might be just right for your application. > > > > On 7/9/20 2:23 PM, R C wrote: > >> Hello, > >> > >> this is (probably) off topic, been seen that happen. If it is please > >> ignore it. > >> > >> > >> I am building a "motorized" telescope mount (dobsonian) with what is > >> called an equatorial platform, it has 3 axis which I am going to > >> drive with stepper motors. > >> > >> > >> The stepper motors I use with a stepper driver, those common DM542 > >> ones, the stepper motors themselves are 2A and 1.8 degrees per step. > >> > >> > >> What I want to accomplish with the equatorial platform) (it > >> compensates for the rotation of the earth) is that, the start and > >> end position accuracy is not that important, smooth and > >> constant/consistent movement is. for the azimuth/altitude precision > >> is not a really big deal, but you'd want to move these 2 axis > >> somewhat swift. > >> > >> > >> So there are a few factors to decide. > >> > >> > >> I probably want micro stepping, what settings on the driver for > >> pulses per rev, is best to use (or is that just trial and error?) > >> > >> > >> As with PWM itself, I am probably just not too familiar with it. From > >> what I understand, the voltage I use for the motors determines how > >> fast I can go (I am going to use a 48V switching power supply). > >> > >> > >> as for PWM, I can of course change the length of the pulse itself > >> and, independently, change the time between two pulses. What is the > >> relation ship there? WHat does a longer width of the pulse itself > >> do? and what exactly does a longer gap between the pulses do (of > >> course the wider the gap between two pulses the slower the motor turns). > >> > >> > >> for, especially, the equatorial platform, I want to avoid "jerking" > >> it, meaning starting and stopping the stepper motor as little as > >> possible and just go at a 'slow' constant speed. > >> > >> > >> > >> sorry if totally of topic.... > >> > >> > >> thanks, > >> > >> > >> Ron > >> > >> > >> > >> _______________________________________________ > >> 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 > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
