Author Topic: Servo position  (Read 1066 times)

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Offline Ecir HanaTopic starter

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Servo position
« on: November 23, 2009, 07:19:45 PM »
Hello,
if I understand this correctly to move a servo to a certain position one has to drive the signal wire with desired PWM value so long until it finally moves there. Is this correct? How do I know then if the servo is already in the position or if it is just moving there? I mean, a servo is left and I want to turn it right - how to I know that it stopped moving and is on the right hand side?

Offline madchimp

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Re: Servo position
« Reply #1 on: November 23, 2009, 07:39:19 PM »
Hobby servos don't have feed back so you have to just trust that they will go to where you tell them. There are ways to add position feed back to them though.

Offline Soeren

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Re: Servo position
« Reply #2 on: November 24, 2009, 11:23:38 AM »
Hi,

[...] drive the signal wire with desired PWM value so long until it finally moves there.
You make it sound really slow.


How do I know then if the servo is already in the position or if it is just moving there?
What's the reason you need to know?


I mean, a servo is left and I want to turn it right - how to I know that it stopped moving and is on the right hand side?
Oh well, either detect position optically or measure the current draw.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Ecir HanaTopic starter

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Re: Servo position
« Reply #3 on: November 24, 2009, 10:00:10 PM »
Quote
What's the reason you need to know?
I wanted to perform a sequence of action based on the completion of previous steps.

Quote
You make it sound really slow.
Ha! Actually, thanks a lot! If the servo doesn't make any noise - it's there! Just wire up some mic to ADC... Or hall sensor for the rotor...
« Last Edit: November 24, 2009, 10:01:35 PM by Ecir Hana »

Offline madsci1016

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Re: Servo position
« Reply #4 on: November 25, 2009, 12:09:50 AM »
Ha! Actually, thanks a lot! If the servo doesn't make any noise - it's there! Just wire up some mic to ADC... Or hall sensor for the rotor...

...or a current sensor to the servo!!! ( as stated before)

That would be a better idea as it would be immune to interference. The mic would pic up everything making noise.

 


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