stepper missing at 220-268 steps/sec

Hey people,

i have a stepper motor that i just conected to a polulu 8825 driver (nema 17), driver is run by a due.
driver is powered by the dues 5v output, the due is powered by a 9v plug in power pack. the drivers motor supply is powered by a bench top power supply and is running at 12v.
I have set up the driver to limit the current about 15% below the motors rated current.

i have run the stepper (full step only) at all sorts of acceleration and speed settings, acceleration settings dont make a difference to the problem. i have run the stepper up to 3000rpm so i know the code is fast enough. but between 220 and 268 steps/sec the motor is real twitchy, ie it turns the opposite way it should by the looks of it randomly. visually between that speed range i would say the stepper shakes back and fowards but doesnt go anywhere. even at high accel rates you can still here the twitch.

im leaning towards some sort of frequency problem, any ideas where to start to trouble shoot.

fairly new to all this electrickery so be gentle.

ps. i have a 100uF cap over the motor supply right next to the driver as they suggest. and the whole setup is on a breadboard

You have discovered mid-band resonance, the thing they don't tell you about steppers in the advertising,
but all steppers have big problems with resonance if run unloaded.

So load the motor mechanically (belt drives are fairly good at dissipating resonant energy, note).

Also you are using full-steps - never do this, its by far the worst for resonance. Try x8 or x16 microstepping
in the first instance. If you want to use full steps, you have to stay below the resonance speed or add
really good mechanical damping. Even with microsteps some sort of damping is useful.

Also full-steps are very noisy, microstepping reduces audible hums and whines.

Does it miss steps when you set the current limit for the full motor coil current

Post a link to the datasheet for your motor.

How much current can the 12v power supply provide?

Post the program you are using.

...R
Stepper Motor Basics
Simple Stepper Code

Hey mark,

my thought on your comments.

mechanical dampening may work under accel, maybe not under decel???????????????

because the affected steps/sec speed is so low, i should change the program to operate with a microstepping scalar under a certain speed setting, and then switch to full scale after to maintain max speed????

is there a hardware way of eliminating this issue??

i initially thought it might have been an issue with a floating signal on the direction pin, the setup is a bit have a few beers and see what happens.

thanks for the input

happy new years

found this on a website "Dynamics of Hybrid Stepper Motors | Machine Design"

At specific step rates stepper motors often experience an undesired reaction called resonance. The indications are a sudden loss of torque with possible skipped steps and loss of synchronization.

Resonance is inherent in the design and operation of all stepping motors. Slow stepping rates combined with high rotor inertia and elevated torque produce ringing as the rotor overshoots its desired angular displacement and is pulled back into position. Resonance arises when the step rate coincides with rotor ringing, typically about 100 to 200 steps/sec. Unable to overcome the combined effects of both load inertia and ringing, the motor skips steps and loses torque and synchronization.

Changing any one of the three parameters — inertia load, step rate, or torque — will reduce or eliminate resonance. As a practical matter, only torque is the easiest to change using a technique called microstepping.

micro electronics means think small and quick.

this makes sense, thanks for the lead.

"How do you minimize stepper motor vibration? - Electrical Engineering Stack Exchange"

Using full step driving, the rotor acts much like a Spring-Mass-System, with the rotor being the mass and the magnetic force being the spring. When you move from one step to the next, the motion will always be rough. The rotor pretty much jumps from one step to the next and it takes some time until the spring dampens out the rotor's energy, causing a little oscillation (read: rough motion).