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Topic: Servo motor range only 90 degrees? (Read 11602 times) previous topic - next topic

longstaff

In the text the servo motor is supposed to give 180 degree of motion, even suggesting cutting out a "half circle" to make the dial on.
My servo is only giving me 90 degree motion, which is supported by the picture on page 69 giving only a quarter circle for the dial.

Anyone know which one is supposed to be correct? or which is working for you?

retrolefty


In the text the servo motor is supposed to give 180 degree of motion, even suggesting cutting out a "half circle" to make the dial on.
My servo is only giving me 90 degree motion, which is supported by the picture on page 69 giving only a quarter circle for the dial.

Anyone know which one is supposed to be correct? or which is working for you?


Not all servos can actually move a full 180 degrees, that is just an assumption the arduino servo library uses. Perhaps a link to your specific servo may shed light on the topic?

Lefty

longstaff

the servo is the one that is included in the starter kit.

on further study there is an obvious number on it that is a product code (SM-S2309S) that states movement of about 60 degrees on the data sheets, so its just incorrectly stated in the book.
next time I might actually look at the component...

Thanks

retrolefty


the servo is the one that is included in the starter kit.

on further study there is an obvious number on it that is a product code (SM-S2309S) that states movement of about 60 degrees on the data sheets, so its just incorrectly stated in the book.
next time I might actually look at the component...

Thanks


Well the datasheet I found doesn't give the total travel range. http://www.servodatabase.com/servo/springrc/sm-s2309s

The spec listed:
Quote
4.8V: 0.12 sec/60°
6.0V: 0.10 sec/60°


Is a speed specification telling how many degrees it can move in so much time at what operating voltage.

The total range specification is shown as:

Quote
Rotational Range:   ? (add)


Lefty

JohnClavis

That's the exact model # of the servo listed on the arduino website (arduino.cc)! You can read the # on the sticker on the photo of the servo! Just look up "servo" -- there's only a couple! They list the range of movement as 180 degrees! It's right there on their site! I'm about to order one based on the assumption that it's accurate! I hope it is!

Stefano2800

I have found this datasheet: http://descargas.cetronic.es/microservo.pdf
apparently total range is 120°

Stefano2800

I tried my sevo, from the Starter Kit, it moves almost 180°
But I was thinking that, if you reference the movement of your servo to a voltage, like in the Project05, when you map the voltage values and angles you assume that the output of the pot will be 0 to 5Vdc.
Well make sure it happens, maybe for some reasons you have lower maximum output and so you will never get to 180°, in this case you have to remap using the max voltage you can  get...
Probably it is not your case, but it may help someone else in future...

JoseSolanoCR

may be i am a little late with this... but i was at the same point with the servo of my arduino kit.... "almost" 180 degrees.... after a short (long) reading and testing... used this on my code...


void setup()
{

  servo1.attach(7);
  servo1.writeMicroseconds(2300);
 

}

this  function actually make my servo turn 180 degrees....

Phaelos

!!Warning!!  Any unconventional testing of failed components adds considerable risk of damage to any and all components attached!  You have been warned...

Old topic yes, but apparently still somewhat relevant.  Received an Arduino kit about a year ago and have been learning much about the interplay of software and hardware.  Has been an amazing though sometimes hair pulling adventure.  So, what I've learned of the supplied SM-S2309S servo motor. 

There is always someone shouting "It has to have it's own supply of at least 1 Amp and exactly 5 Volts."  Truth is, if you're making relatively slow movements, you're fine with barrel jack power supply (mine is 9v 1.3A) and passing the current through the 5v line.  Definitely DO NOT power through the I/O lines or with only usb power as these routes put the arduino and associated computer at unnecessary risk of overload.  This was just for limited duration testing at slow adjustment rates.  I've had no issue with 2000ms between adjustments.  That said, the on board regulator did get warm with 200ms between.  So...  Be careful if you don't have a decent secondary power source with correct ratings or are still learning how to interconnect multiple sources of energy.

Now for the good stuff.  The servo was about 40 degrees away from 0 stop at 0 degrees.  Limiting motion to about 140 degrees.  Way better than 90 but still pretty crap.  To fix this, I opened the servo to re-allign the innards so now the servo can achieve the full 180 + degrees of motion.  However, even with full motion, the code for the servo in degrees is 0 - 149.  A discrepency of about 30 which if I needed would have to figure in to the calculation of the position.

Note:  Don't take stuff apart unless you are ready to throw it away.  Yeah, a 180 degree servo only capable of 140 was about to get trashed.  Just sayin...  Maybe this is helpful to someone.  Maybe not.  Best wishes all the same.

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