On Sat, Oct 11, 2014 at 11:30 PM, Al B <[email protected]> wrote: > Ytai, > > Regarding your point #2. The stepper motor is rated for 1.2A so I set the > current limit on the DRV8834 > <http://www.pololu.com/file/0J617/drv8834.pdf> drive to 1.2A by setting > the reference voltage to 0.59V* (Current Limit = VREF × 2*) > > Should I increase the reference voltage to a higher value so the torque is > increased? >
No. Exceeding the rated limit is not a good idea. If all else fail you may need a motor with higher rating (and possibly a beefier driver). > > Can you please explain a little bit what you meant with #1 and #4 (Reduce > the load and slow down)? > Reduce load = make it so the motor doesn't have to work as hard, for example, reduce friction, use smaller wheels, use some kind of transmission. Slow down = limit your maximum speed (which is really just a crude, simple way of limiting acceleration, which is what you're actually after). > Are you suggesting to use 1/16 or even 1/32 microstep resolution instead > 1/8? > I think that in general more microstepping = better. It results in a smoother motion. Unless you're bound by the maximum pulse rate your controller can generate or your driver can handle, there should be no good reason to reduce microstepping. > > Thanks, and best regards! > > > > On Saturday, October 11, 2014 9:55:37 PM UTC-7, Ytai wrote: >> >> The stepper is missing steps when its cannot accelerate fast enough to >> keep up with the electric commutation. You can mitigate this by: >> >> 1. Reduce the load on the motor. >> 2. Increase torque ~= current, if your motor and driver are capable >> of it. >> 3. Rate-limit the speed change (i.e. limit acceleration). >> 4. Slow down. >> >> >> On Sat, Oct 11, 2014 at 8:25 PM, Al B <[email protected]> wrote: >> >>> When I try to setup the period with a value under 40, then the stepper >>> <http://www.pololu.com/product/1200> motors stop moving and start >>> vibrating like they are missing steps. By looking at the ShoeBot app, it >>> seems that Ytai is able to set the period as low as 15. I using 2 of these >>> DRV8834 <http://www.pololu.com/file/0J617/drv8834.pdf> Low-Voltage >>> Stepper Motor Drivers with a 1/8 microstep resolution; which are a little >>> bit different to the A4988 >>> <http://www.pololu.com/file/0J450/a4988_DMOS_microstepping_driver_with_translator.pdf> >>> drivers used on the ShowBot. However, I don't think they are imposing this >>> limitation. My app also uses a CLK_62K5 clock and the loop() method >>> updates the period every 2ms. >>> >>> Any suggestion or comment will be appreciated. >>> >>> Thanks! >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "ioio-users" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/ioio-users. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- > You received this message because you are subscribed to the Google Groups > "ioio-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/ioio-users. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "ioio-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/ioio-users. For more options, visit https://groups.google.com/d/optout.
