Need Help!- An Odd Situatition

[herring_fish]

I have an issue that turned up after installing my stepper motor. Please take a look at this Youtube link.

WhyThis - YouTube

WhyThis - YouTube

The stepper motor that I am using is a 57BYG, 1.8 degree 12V running at 30 V, 4 phase, 0.6A per phase, inductance per phase 25mH, 100Mohm, class B, rotor inertia 38gcm2, hold torque 6Kg.cm, mass 0.65kg

[P.Passuello]

You are encountering motor resonance. Adding the gear on top is changing point at which the motor resonates. The whining noise you are hearing is not the motor binding but you have your maximum speed set too high for the motor / driver combination. Slow it down and it will run ok. If you are using a Gecko drive tune the driver.

Cheers
Peter

[herring_fish]

Thank you for writing back. I thought about resonance so I turned down the speed from 255 to 200, 150, 100, 50 and 60. I do believe that you are right though. I can almost see it. This is a hand-me-down. Do motors get more finicky with age and/or miss-use? These motors are cheap. Should I just buy a new motor. Should it be the next size bigger....or is the issue that the motor is too cheap for my application?

I use a Rugged Motor Driver.

[herring_fish]

I wrote to rugged support and got this back from them. I will try this tonight. I believe that I have already have the TCCR2B = _BV(CS21); code in my sketch
I do have a few lines for acceleration but hopefully this will be better.



The issue of "12V running at 30V" is a bit confusing. Are you otherwise controlling the average motor current within the safe level of 0.6A?

There are 3 things that could be going on here (as a first guess):

* Your PWM frequency is too low for the small inductance of the motor (or really, the L/R ratio, inductance to resistance). You can increase the PWM frequency for analogWrite() commands by setting a lower prescale value for associated timer. For example, if you look at our Stepper Demo sample application you will see the following code in the setup() function:

// Change from divide-by-64 prescale on Timer 2 to divide by 8 to get
// 8-times faster PWM frequency (976 Hz --> 7.8 kHz). This should prevent
// overcurrent conditions for steppers with high voltages and low inductance.
TCCR2B = _BV(CS21);

If the PWM frequency is too low, the Rugged Motor Driver will go into a temporary overcurrent condition on each PWM cycle if you are driving a 12V motor at 30V.

* Your motor current is not high enough to move the mass that it is being asked to move. Frankly, at 30/12*0.6=1.5A per phase this does not seem likely for the mass you are trying to move.

* You are not accelerating up to the target speed. Stepper motors have much lower torque than their ratings at high speeds, and if you just simply start stepping without ramping up the speed you will see the type of behavior in your video. Consider using the AccelStepper library which has built-in support for ramp-up/ramp-down of speed:

AccelStepper: AccelStepper library for Arduino

[herring_fish]

I got it working thank you. Despite trying all kind of speeds initially, after changing a couple of other things, I was able to get it to run as 150 max speed instead of 300 that it use to run at. I'm cycle testing it now.

P9110046 - YouTube

P9110046 - YouTube