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### Topic: regarding  speed of continous rotation servo motor (Read 2148 times)previous topic - next topic

#### real

##### Oct 21, 2010, 03:02 pm
hello ,
i m working on autonomous robot. i m using two continuous rotation servos  which are centered for 1500 microseconds. to move this robot in forward direction we have to give larger pulse  than 1500 for right servo and  pulse less than 1500 for left servo. wheels are attached to these two servos. following is the combination
right servo pulse 1600 microseconds
left servo pulse  1400 microseconds

after uploading program this bot moves in  forward direction  but speed of left servo more than right servo ,so it doesn't   move straight

#### PaulS

#1
##### Oct 21, 2010, 04:06 pm
The exact no-motion value may not be the same on both servos. The speed of rotation when moving a fixed value away from stopped may not be the same on both servos, and may not be the same in each direction on the same servo (that is a delta of +100 and a delta of -100 may not result in the same number of rpms in each direction). Welcome to the real world.

If you need to make independent servos track precisely, you will need to add some sensors that can report the actual speed that the servo is turning, and use that feedback to adjust the values written to the servos.

#### real

#2
##### Oct 24, 2010, 10:45 am
thanks for ur suggestion.
how can i identify  maximum speed of servo with command  "Microsecond"  without sensors . because  when i give command  'writeMicroseconds(9500) to a servo motor it is moving clockwise even though  its range is 500-2500

#### Groove

#3
##### Oct 24, 2010, 10:50 am
9..5 ms out of a frame time of 20ms is silly.
What are you trying to do?

#### real

#4
##### Oct 24, 2010, 11:29 amLast Edit: Oct 24, 2010, 11:31 am by real5750 Reason: 1
i write 1500 microseconds which stops servo, when i write 1800 which  moves  the motor in clockwise direction .
my question is how i can find   microseconds for maximum speed.
while experimenting i just write 9500 and servo is moving  in clockwise direction

#### Groove

#5
##### Oct 24, 2010, 12:26 pm
What happens with pulse lengths of, say, 1000us?

#### Korman

#6
##### Oct 24, 2010, 12:28 pmLast Edit: Oct 24, 2010, 12:31 pm by Korman Reason: 1
Real,

common RC-servos for hobby usage - and that's what's the Servo library is written for - work in a range from 1000µs to 2000µs with 1500µs being the middle. Some may extend that range to 500µs to 2500µs with 1500µs still being the middle. If your motor work differently, you're going to need a data-sheet for it which will describe exactly what's necessary. Speculation would be a pointless exercise.

You should get the data-sheet of your servo anyway, because if it involves some kind of electronic speed control (ESC), you might need to calibrate it. Only reading the data-sheet will tell you that, psychic divination on an internet forum won't help.

Korman

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