Hi!
So a few days ago I bought a new Servo. After a short time the Servo broke and started acting strange (barley turned and if it did only in one direction). So I went to the store I bought it from and asked what I did wrong or wheter the Servo had a defect. They said that the electronic of the Servo burned up (got really hot).
I am rather new to Servos and really dont know much about them.
Therefore i asked them what was the cause of that and they told me that I probably adressed the Servo with the wrong frequency (dont know wheter this is the right name for it).
I simply used the example code of the standart Servo library:
#include <Servo.h>
Servo myservo; // create servo object to control a servo
// twelve servo objects can be created on most boards
int pos = 0; // variable to store the servo position
void setup()
{
myservo.attach(9); // attaches the servo on pin 9 to the servo object
}
void loop()
{
for(pos = 0; pos <= 180; pos += 1) // goes from 0 degrees to 180 degrees
{ // in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position
}
for(pos = 180; pos>=0; pos-=1) // goes from 180 degrees to 0 degrees
{
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position
}
}
The Servo got the power from an external source (battery pack), but im sure i connected everything the right way and the battery pack delivers the right voltage.
Is it really possible that the servo broke because of that?
Now i still have a Servo at home (This one) I dont want to make the same mistake again, so can anyone tell me what i did wrong?
You need to tell exactly how you connected it up, the exact nature of the battery pack, because
the fact you burnt it out implies you did something wrong. Also what were you doing with the
servo? Did you overload it mechanically? (That always cooks a servo).
I got a 6V/3000mAh NiMH battery pack which consists out of 5 batteries (I didnt do that myself however, i got that in the store). Since I need a connection of the ground of the Arduino and the battery pack i solded some cabels in there, but I'm pretty sure I did that right. Then i connected the + of the battery pack with the + of the Servo and the ground aswell. I also connected the ground of the Servo and the Arduino and connected the signal of the Servo and Arduino.
The Servo had to lift about 16kg for like 20 seconds, but the force was just 1cm away from the center of the Servo. In the store i was told that I should be able to life 16kg with the Servo for about half an hour.
1.6Nm continuous torque from a device rated at 2.3Nm max? No, that's going to cook it good!
The maximum torque happens at maximum current, which is about 4A I think looking at the
stats, so it will cook rapidly indeed.
The ratings are 2.3Nm at 6V, 7 rad/s at 6V. Multiply those and you get 16W mechanical max
power, which means about 25W or so electrical (ie 4A). Something that size with 25W dissipating
will be melting within a minute!
Servos are not designed for continuous max torque use at all - the peak torque is there for
rapid accurate response, not working against a constant load.
What are you actually trying to do? Perhaps a hobby servo is not the best method...
Im trying to build sort of a water pump that pumps water in a plexiglass tube. I want to achieve that by squeezing a waterballon with a Servo. My teacher, who by now i know has no idea of that stuff, told me that i could easily achieve that with a Servo for 10$ instead of a linear accutor. So i build everything according to it and now I'm stuck on Servos
Well in the store I was told that there wouldnt be any problems with this Servo. They told me aswell that Servos arent made for continious torque, but that 16kg shouldnt be any problem with that Servo with a max holding power of 280/320 Ncm.
So it really was that it couldnt handle the force after all?
Thanks for the help btw ^^
16kgf force is a lot - perhaps some figures about back pressure, flow rate etc are needed to see
if you are in anything like the right ballpark. If I put 16kgf onto a balloon filled with water I would
expect it to burst.
Well the ballon is connected to a 65cm long tube with a diameter of 2.3cm. The ballon is way more robust than normal ballons and the pump is specifically designed for a ballon(the shape of the plate that puts the pressure on the ballon is in the exact shape of the ballon). The ballon wont be the problem i think.
The only problem i have at the moment is the Servo. So is it actually possible that the electronic got burned by using the sample code of the libary?
I wonder could you organize the mechanical arrangment so that, for example, when the servo has moved to maximum extension (max squash on the baloon) the load, the servo arm and the servo shaft are directly in line so that the load is all taken on the bearings without any need for motor power.
Ok at this point i guess ill have to quickly explain the whole project:
The goal is to be able to control the water level in the tube so that it's an accurate representation of the decibel value of music playing. Therefore the Servo will have to be able to move between position 0° and 90° (more or less).
I tried to accompish your idea aswell as possible already, but it still takes quite some force (both to push and hold).
A fairly beefy and fast linear actuator might be more plausible - getting one that's
fast enough and powerful enough could be tricky. 160N force moving at speed means
a lot of power. Power = force x velocity.
