Silent Stepper Motor Control - Page 1
Forum section: electronics / beginners

author: selkathguy
author_rank: Unknown
timestamp: July 16, 2014, 01:34:22 pm
content: I found this a while back:I've not been able to find anything about silent steppers, which led me to believe it has to do with the way in which you drive the stepper. Someone said microstepping is the key to making it quieter, but I've seen plenty of microstepping videos and they're still loud. I guess what I'd like to know is how are they making it so quiet? Is it just the quality of the motors? Crazy high stepping frequency? Some voodoo with the drive waveforms?Perhaps some VSD-XE magic.

author: rob77
author_rank: Super Contributor
timestamp: July 16, 2014, 01:37:15 pm
content: the steppers will be always clicking, whining and screaming - no matter what you do

author: selkathguy
author_rank: Unknown
timestamp: July 16, 2014, 01:39:45 pm
content: Quote from: rob77 on July 16, 2014, 01:37:15 pmRight, and I understand there will always be some noise, but what matters to me is banging down that noise as much as possible, and I was curious if there were any methods for pursuing that goal. And unless that video is fake, someone has managed to do it.

author: PE1RKI
author_rank: Regular Contributor
timestamp: July 16, 2014, 01:47:25 pm
content: at a certain motor speed you can cancel out the noise.the video shows the motor moving a fixed speed, suspicious!but if they are indeed silent drivers, give me 5 now and take my money!

author: selkathguy
author_rank: Unknown
timestamp: July 16, 2014, 01:50:16 pm
content: Quote from: PE1RKI on July 16, 2014, 01:47:25 pmThose drivers are 300 bucks a pop. lol

author: rob77
author_rank: Super Contributor
timestamp: July 16, 2014, 01:53:18 pm
content: that video seems fake to me (but i might be wrong!) - the background noise is audible, but not a single noise from the machine - that's strange. at least a little noise from the bearings and the motors should be audible.and regarding your question:well.... to achieve the designed torque of a stepper whilst maintaining the steps - you have to drive it hard. once you do that it will click or scream at higher rmpsyou could make some magic in terms of "soft" stepping - e.g. slowly ramp up the current, or PWM it to achieve smooth transition to the next step - but both torque and accuracy will go away - effectively eliminating the benefit of a stepper (which is maintain position and reproducible accuracy).

author: fcb
author_rank: Super Contributor
timestamp: July 16, 2014, 01:55:06 pm
content: I've built silent stepper motor drives for various projects over the years.The way I've done it is to use a sine table and generate a pair of sine and cosine PWM's, these then drive LMD18200T's H-bridges. By monitoring the current I can slowly change the 'gain' of the PWM to get the torque.

author: GeoffS
author_rank: Unknown
timestamp: July 16, 2014, 02:03:34 pm
content: I useGeckodrives for any stepper motor project and, properly tuned, they are almost silent.In that video, the steppers are fitted with encoders, perhaps that's a clue to how the controller works?

author: rob77
author_rank: Super Contributor
timestamp: July 16, 2014, 02:13:24 pm
content: Quote from: GeoffS on July 16, 2014, 02:03:34 pmso probably as i said - soft transition between steps - and losing the accuracy and torque - and they compensate for that in the controller based on the encoder feedbacknow the only question is ... is it worth it doing that with steppers ? a geared brushless with encoder would be cheaper i think

author: PE1RKI
author_rank: Regular Contributor
timestamp: July 16, 2014, 02:14:37 pm
content: Quote from: selkathguy on July 16, 2014, 01:50:16 pmthats 200 euro in real money, not far of from the gecko drives. and these are still humming to me.

author: selkathguy
author_rank: Unknown
timestamp: July 16, 2014, 02:24:43 pm
content: Quote from: fcb on July 16, 2014, 01:55:06 pmThis is helpful! When you say 'sine table', do you mean an entry with sine and cosine values for each microstep? Or is it even microstepping at this point

author: selkathguy
author_rank: Unknown
timestamp: July 16, 2014, 02:28:10 pm
content: Quote from: rob77 on July 16, 2014, 02:13:24 pmOne of my constraints is space near the actual motor. I can't afford space for extra encoders as it's an embedded application, and I need to retain accuracy.Might be a more realistic representation of sound. It's still acceptably quiet.

author: WarSim
author_rank: Frequent Contributor
timestamp: July 16, 2014, 03:08:25 pm
content: In mode 0 my vacuum is silent too..Any stepper can be near silent with process micro stepping, very low applied torque and no induced intrinsic torque.Ie: Constant velocity lower than the field transfer speed, with no load.After all a stepper motor is held I place with more than happy thoughts.Sent from my iPad using Tapatalk

author: mrflibble
author_rank: Super Contributor
timestamp: July 16, 2014, 03:14:09 pm
content: Quote from: rob77 on July 16, 2014, 01:53:18 pmSeems legit. You can hear a cyclical sound along with the arm moving, and at the end you can also hear it when it quickly rotates back to the starting position.