[SOLVED] Servo making clicking noise

GoPiGo
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Hello,

Whenever I send commands to the servo to move it makes a noise; I must say it moves to where it is supposed to but even after reaching the final position the noise is there.
Could it be that I need more power to drive the servo?

Thanks

2

Hey,
The noise is due to the fact that the Servo is using software servo instead of hardware servo and hence does sometimes gives jitters. It not a big problem and we are working to get rid of it.

-Karan

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I realize this post is over two years old, but I just purchased a GoPiGo Starter Kit (with a GoPiGo2 and Raspberry Pi 3) and the servo still has this clicking sound. Is this still a known issue, and something I just need to deal with? Can someone recommend a better servo?

Here’s a video of what I’m talking about:

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Hi @zooce,

Thank you for being thoughtful for sharing with us a video of your servo.

Just as @karan said, it’s because the GoPiGo uses the software servo.
With software servo, it’s normal to have some jitter, which in turn causes that clicking sound.

Using a better servo won’t do, because it isn’t related to how good the servo is - it’s all about the signal that’s sent to the servo. And the signal that’s sent by using a software servo isn’t going to be stable.

Do you face any serious problems because of the noise?

Please, tell us if the noise is affecting your project. If it’s affecting then we will try to make it more stable.
Also, contributions that seek to solve this issue are also well-received.

Thank you!

5

Thanks for the quick response @RobertLucian.

It’s not causing an issue for me right, now. I really just wanted to make sure that I don’t have a faulty servo.

By a better servo, I meant a servo that didn’t have so much jitter. As @karan mentioned, there are hardware servos, which don’t have this jitter. Is there one (or more) that you could recommend using with a GoPiGo2?

6

Hi @zooce,

Jitter on a servo can come from 2 places:

  • the signal generator - aka the GoPiGo

  • the servo - caused by cheap sensors within the servo

Most of the jitter the servo encounters comes from the GoPiGo. If you’d hook up a state-of-the-art servo, it would still have jitter and quite a lot - because of the GoPiGo.
Yes, it’s also possible that the servo has some jitter on its own, but that’s neglectable compared to what the GoPiGo generates.
If you really want to go that route (by getting high quality servos), you wouldn’t have great benefits from it. To the naked eye, it’s going to be same jitter.

FYI, the high quality servos use and I quote

optical or magnetic absolute encoders.

Here’s a post on stackoverflow that talks more on this subject: https://electronics.stackexchange.com/a/77536

Also, what do you mean by

there are hardware servos, which don’t have jitter

If I’m correctly guessing, you’re thinking that there are software and hardware servos, physically-speaking. Well, that’s not the case.
When we we’re talking about software and hardware servos, we were referring to how the PWM signal is generated on the GoPiGo.

  • hardware-generated PWMs (for the servos) are really the thing you want to use if you want high-precision. Unfortunately, it’s going to leave you without certain timers available and so you won’t be able to use the chip (aka the GoPiGo) to its full extent.

  • software-generated PWMs (for the servos) are useful when you want to keep all the chip’s functionalities (like the sleep function), but the only downside is that these signal are not stable - hence the jitter. We’ve went this way because we wanted to have a little bit of everything.

Please let me know if there’s anything else unclear.

Thank you!

7

@RobertLucian,

I actually didn’t know what a hardware servo was. I was kind of quoting @karan’s post:

Thanks very much for the details about how servos work!

8

Hi @zooce,

Your welcome!

I think that’s because of the jargon. It happens when you spend lots of time tinkering - you start cutting words out of the phrase in order to get to the point faster.

I think we can close the topic now.
I’m setting a timer on it in case there’s anything else you might want to add.

Thank you!

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This topic was automatically closed after 27 hours. New replies are no longer allowed.

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