I've stalled servos for considerable time and, as Niel stated, it eats up
your battery.  No damage to the servos.  Metal gears are good for protecting
against sudden forces on the servo head.

With plastic (standard) gears, snap a strong spring tangential to the head,
then go down to the hobby store and buy yourself a new set of gears. :-)

As you're into robotics, check out http://cnjarc.homerobots.us.  I have a
lot of links there you may find useful.

Derek Cowburn
derek@cowburn.us, www.cowburn.us


> -----Original Message-----
> From: Pic Dude [mailto:picdude@PILOTTOOLS.COM]
> Sent: Wednesday, July 31, 2002 2:57 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE] Servos and Strain
>
>
> The servo will "jitter", which IMHO is not good.  The reason
> is that the force on the arm will be enough to just move the
> pot wiper, and this will tell the controller to push the motor
> a bit more, which will relax the motor, which will allow the
> force on the arm to shift the pot wiper again, etc, etc, etc.
>
> I'd not be too worried about stripping gears (unless you're
> really overloading them), but more from wearing a dead spot
> on the pot, or destroying the motor by repeated flickering.
>
> Since, as you indicated, servos tend to use power somewhat
> proportional to the load on them, this is also not good from
> a power-consumption perspective.  In my past life when I was
> really into RC airplanes, I noted that if any control surface
> jittered due to binding, then battery life was significantly
> reduced.
>
> I don't think you need to worry about the control circuit in
> the servo handling the current, but instead if your power
> supply can hold up.
>
> Either way, if the servo is known overloaded, which it seems
> you do know, then it it obviously not designed for that use,
> and should be replaced with something higher-torque.
>
> Cheers,
> -Neil.
>
>
>
>
> > -----Original Message-----
> > From: pic microcontroller discussion list
> > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Nick Stedman
> > Sent: Wednesday, July 31, 2002 1:25 PM
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: [EE] Servos and Strain
> >
> >
> > Hi
> >
> > I'm working on a hobby robot that uses servos for the joints in
> > its legs. I
> > have a couple of questions about them.
> >
> > What happens to a servo when its rotation is consistently
> overloaded with
> > too much weight? Does this damage the motor?
> >
> > Second, when too much weight is placed on the servo, current draw
> > increases
> > substantially. Is this current loaded onto the servo's
> control circuit and
> > if so can it handle the current? I have many servos sharing
> the same power
> > source, so problems relating to current draw are probably
> compounded, no?
> >
> > In fact, I have not encountered too many problems so far.
> If the robot is
> > weighed down it just struggles against its load and resumes
> operation once
> > the weight is removed. This is what I want. I just hope that I'm not
> > damaging the servos in the meantime. BTW I'm using Metal
> Gear servos to
> > reduce the chances of stripping.
> >
> > Thanks in advance,
> > Nick
> >
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