RC- servo motors -anybody can help me ?

[mechatonics]

hi all.
anybody who can help me ? where can i learn about RC-servo motor?
please help me . thanks alot

 

[ivancho]

What is a servo?... is a "smart" geared motor with feedback. YOu can find tons of information on the web about them... google is your friend.

In a nutshell, a servo is a motor with a gearhead mechanisim such that when the motor moves, the gears inside motor also move a potenciometer. This way the electronics inside the servo can know where the shaft is located.

The electronics of the servo has a H-bridge to control direction of movement, and brains to get a signal and transform it to movement.

The signal needed by the servo has to be a pulse. The pulse must be between 1 milisecond and 2 miliseconds, every 18ms. A 1ms pulse will tell the servo to move all the way to the left, and a 2ms pulse will tell the servo to move all the way to the right. A 1.5ms pulse will position the servo at the middle.

Once a pulse is sent, the electronics in the servo will make the motor move towards the position sent very fast, and slows down as it approaches the position, so that it doesn't overshoot it.

Servos take 3 wires, 2 for power and 1 for a signal. They are normally powered by 4.8V but I have actually run mine of a 7.2V battery. That is why they are favorite among hobbiest since they are easy to control, and thy don't need extra-electronics. You can modify the servo, by removing the potenciometer inside and replacing it with the equivalent resistance as when the servo's pot is position in the middle. Then by sending a 1ms or 2ms signal, the servo will always think is in the middle and will try to position itself, but because of the change it will never get there, accomplishing full rotation. During a modification like this one, you must also remove any physical stops that can be found inside the servo what won't allow full rotation.

Good Luck

Ivancho

 

[marchache]

Servo help

Good document here:

https://www.winnipegrobotics.com/cgi-bin/refdoc.cgi?servo

Marc

 

[jbeng]

Here's another good page which might be helpful to you:

It's a short tutorial on how the servos operate. They're quite easy to work with.