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Italy
Asked — Edited

Servo Question

Hello and first of all, scuse me for my bad english.

I am trying to use servos for the movement of my robot, but i see a bad thing.
When servos goes in position i set, they have a vibration..........

For example, i set a servo in 60% position. It goes to the position and it start "buzzing".......

Do you have same problem?
I am thinking using motors and not servos, but it's a difficult way.
If i have many servos, i will have many "buzzing", so, my robot will be very bad..........

Can someone suggest me a solution?
Thank you very much and scuse me for my bad english.


Ema from Italy

AI Support Bot
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Synthiam
United Kingdom
#1  
Buzzing usually indicates it is holding a load and that load may be near to, or even over the maximum torque of the servo.

What is the maximum torque rating of the servo, and what are the weight and length of the part the servo is moving? Did you carry out the relevant calculations?
#2  
Hello ODT , if you have digital servos they Humm or buzz when they are on. It is because the controller pulses 300 times a second and that makes an audible tone.
PRO
USA
#3  
odt,
Buzzing happens when there is a load present, like asking to position out of range or after the desired range is completed, you can try releasing the load to the individual servo# or perform a #Release All
ReleaseAll(0) command.
This will also increase your battery life.
Maybe you asking a load above the capability of the servo, like mentioned by Rich.
Steve S
Italy
#4  
Thank you for the reply.
The servos buzz even with no load, when they are 'on'. I have tried to change servos, but all the servo i have, do an audible tone and a little vibration.

If it is ok, like jstarne1 has explain, i don't like the thing very much because having many servos, i will have many audible tone....
The way 'detaching' servos, is not a good idea because, for example, detaching the head servo, the head will roll down...
I was thinking using motors with encoder, but i don't like encoders very much. Do someone has some other ideas?


Thank you

Ema
#5  
DC Motors are very quite. Sadly EZB doesn't support encoders though. You can use pots attached to the ADC ports of EZB for feedback for position control.

If you want to use encoders you can use a Kangaroo board to take the load off of EZB and handle the encoder functions.
www.dimensionengineering.com/products/kangaroo
Italy
#6  
Can you explain please what is a "pot"?
#7  
Ema, mine buzz too when they are at their max rotation limits (load or no load)... My guess is they are pressing against their stops... Or in my case, possibly due to cheap servos...;)
#8  
A pot is a potentiometer which is a variable resistor.
#9  
My bet is your putting them to the stops farthest to the left and right. If not, it's because the item your turning or lifting is too heavy. Do calculations and see if the item is over the torque rating.
#10  
Servo amps roughly compare a generated pulse width to a "required pulse width. Differance causes the servo to move in the direction that will cause these signals to ballance. This is all ancient history, but is still true whether we are talking about analog or digital servos. If, as we will stipulate, the servo is not mechanically constrained, and if electronics were perfect, the servo would find the one position that exactly ballances the two signals, and wait quietly for the next stick jog. Of course, electronics are not perfect, and comparators have some jitter due to heat, cold, phase of the moon, or whatever, and if the jitter is read by the amp as significant enough, it will try to move a small amount. This causes the servo to buzz,whine, cough, or perform other tricks that are not expected.