Reducing servo motor jitter noise

In summary, the conversation discusses techniques for reducing noise in a digital servo, such as lowering the voltage, using capacitors for noise filtering, and using high frequency noise absorbing foam. Additional suggestions include using a controller that supplies holding current, reducing backlash in the drive system, implementing a deadband in the positioning algorithm, and changing the PWM frequency. The importance of addressing the source of the noise, such as worn motor bearings or a sympathetic frequency, is also mentioned.
  • #1
kolleamm
477
44
I have a digital servo that makes a lot of jittering noise. The motor itself works great, however when you set it to a certain position while applying a force it will make a jittering sound as it tries to find the optimal position, which is pretty common for digital servos to do. My question is how do I reduce this noise?

One method I tried that seemed to work was lowering the voltage. This is a 4.8 - 6v servo, reducing the voltage to 2.8v greatly reduced the noise while still maintaining a decent amount of torque.

I've heard using capacitors for noise filtering on the wires might work as well.
At this point I'm considering using a high frequency noise absorbing foam, since I really just want to get rid of those annoying high pitched sounds. The low pitch I can live with.

Thanks in advance
 
Engineering news on Phys.org
  • #2
You don't want to reduce the voltage as the higher current needed to operate it, while initially offering more torque, will cause motor damage. The higher the voltage you run, the smaller the motor you can use; maybe that could be a solution? Field weakening would allow it to run faster, which may get it past the chatter point, but I don't know if there are any steppers that allow for this {EDIT and it would lower your torque END EDIT}. If what you have will run for a sustained time with the chatter, foam may be the way to go. Many medical appliances with stepper motors rely on the foam.
 
  • #3
True, in that case I would have to put in a regulator to make sure the servo can't draw too many amps at the lower voltage.

At this point I'm just trying to find the best material/method for absorbing high frequency sounds. Acoustic foam so far is my best guess.
 
  • #4
I don't know a whole lot about your exact situation, but I once had some real problems with line noise with some servos I was using. I had to use cabling longer than the manufacturer recommended and as a result, it picked up some additional jittering due to noise those longer cables picked up. I solved that with careful shielding and ferrites. That certainly may not be an issue you are dealing with, but it's something to consider.
 
Last edited:
  • Like
Likes johnnyrev
  • #5
Ideally you should fiddle with the drive electronics to sort this problem out but a common quick fix is to introduce a small amount of friction damping . An O ring inserted between fixed and moving parts is often adequate .
 
  • Like
Likes johnnyrev
  • #6
An O ring sounds like a pretty good idea. Thankfully there are things I can try! Also gladly high frequencies should be easier to cancel out.
 
  • Like
Likes johnnyrev
  • #7
I would like to try acoustic foam, but the foam itself is also a good insulator which would prevent the motor from cooling. Any way around this?
 
  • #8
kolleamm said:
I have a digital servo that makes a lot of jittering noise. The motor itself works great, however when you set it to a certain position while applying a force it will make a jittering sound as it tries to find the optimal position, which is pretty common for digital servos to do. My question is how do I reduce this noise?
Three suggestions:
Use a controller that supplies some holding current when the position is reached.
If the position sensor is not mounted on the motor shaft, reduce backlash in the drive system.
Implement a deadband in the positioning algorithm.
 
  • Like
Likes johnnyrev
  • #9
Is the annoying high frequency a PWM switched power from the H-bridge to the servo?
If so you need to identify the part that is moving and resonant at that frequency. Consider worn motor bearings, lubrication, motor mounts, driveline etc.
Maybe change the PWM frequency away from the sympathetic region.
 
  • Like
Likes johnnyrev
  • #10
Servo controllers work by calculating the difference between the demand position and the actual position. The difference (the error signal) is used to drive the servo in the required direction. Usually small error signals are ignored to stop the servo hunting or buzzing. This is called the dead band. You could try increasing the dead band if it is under your control. The down side is reduced position accuracy. Also it may not stop the buzzing if the servo has to provide a holding torque eg the servo is under a constant load that would pull it out of position.
 
  • Like
Likes johnnyrev

Related to Reducing servo motor jitter noise

1. How can I reduce jitter noise in my servo motor?

To reduce jitter noise in a servo motor, it is important to ensure that the motor is properly grounded and that all connections are secure. Additionally, using shielded cables and adding capacitors can help to minimize electrical interference. Adjusting the servo motor's gain and tuning parameters can also help to reduce jitter noise.

2. What causes jitter noise in servo motors?

Jitter noise in servo motors can be caused by a variety of factors, including electrical interference from nearby equipment, loose connections, or improper grounding. Mechanical issues such as worn gears or misalignment can also contribute to jitter noise.

3. Can servo motor jitter noise be eliminated completely?

While it is possible to greatly reduce jitter noise in servo motors, it is difficult to eliminate it completely. Some level of noise is expected in any motor, but following best practices for reducing noise can help to minimize its impact on performance.

4. Does the type of servo motor affect its jitter noise levels?

Yes, the type of servo motor can have an impact on its jitter noise levels. Brushed DC motors, for example, tend to have more jitter noise than brushless DC motors. Additionally, lower quality servo motors may have less precise movements, resulting in increased jitter noise.

5. Can excessive jitter noise damage a servo motor?

In most cases, excessive jitter noise will not cause any damage to a servo motor. However, it can affect the motor's performance and accuracy, so it is important to address and minimize jitter noise to ensure optimal operation.

Similar threads

  • General Engineering
Replies
1
Views
3K
Replies
9
Views
2K
  • Electrical Engineering
Replies
10
Views
4K
Replies
4
Views
4K
  • Electrical Engineering
Replies
5
Views
3K
Replies
5
Views
1K
  • Electrical Engineering
Replies
17
Views
3K
  • Electrical Engineering
Replies
15
Views
3K
  • General Engineering
Replies
1
Views
10K
  • Electrical Engineering
Replies
5
Views
2K
Back
Top