hobby servomotors

[anthony witcher]

Hello guys,

When I got my Anthony Bot up to running after being on shelf for many years,

it didn't run very well. I replaced batteries and re-programed the software.

It still didn't work.

Then when I went back to eliminate some program lines to trouble-shoot,

I noticed the continuous servomotors weren't running right. It wouldn't reverse well like it used to be.

This got my attention.

Before I attempt to replace the servomotors, I am wondering, do those small

hobby servomotors wear out?

Anthony

[Erik Kauppi]

They might wear out from high miles, they have plastic gears.  Or break at low miles from overloads, again plastic gears.  But I would not expect them to wear out or age out from sitting on the shelf (unlike batteries).

Swapping servos is a good idea.  Or put a 'scope on the signal line to the servos to see what they are being commanded to do.

-- Erik Kauppi

 

Erik Kauppi

Program Manager

Office: (734) 389-8588

eka...@tm-lift.com  I www.tm-lift.com

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Ann Arbor MI 48108

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[Tom Atwood]

Before I attempt to replace the servomotors, I am wondering, do those small

hobby servomotors wear out?

Yes, like all mechanical devices, they don't last forever. Small, inexpensive hobby servos used in very affordable toy products will wear out if used a lot, but it does not happen all that frequently; usually, the problem with a cheap servo turns out to be a stripped gear in the servo. That is, they can break internally. 

The permutations of possible servo features are many.  Hobby servos come in a large variety of physical sizes and output torques, internal speed control type, with choices in control system software, gearing, input volts and amps, output wheel type and degrees of rotation clockwise and counter clockwise (some offer continuous rotation output to drive wheels, boat props), etc.  

Cheap hobby servos serve a low-cost "disposable toy market," and pricier 'robot' servos range in quality and price depending on the sophistication of the product and application. You can get a quick idea of the types of servos out there by reviewing the Humanoid Buyer's Guide published in now out-of-print Robot magazine, but it is still available online, here:http://www.botmag.com/humanoid-buyers-guide/ . Humanoids are largely made by connecting servos together in the shape of a person, and then programming the servos to execute coordinated movements.  This guide details the components (including servos) of all the humanoids that were available when that guide was written in 2011. The guiding principles remain the same to this day. A comprehensive listing of servos can be found here: https://servodatabase.com/

On Mon, Oct 29, 2018 at 8:58 PM anthony witcher <anthony.w...@gmail.com> wrote:

[Tom Atwood]

Hey Mr. Kauppi,

To my dismay, I have found out that plastic, itself, can wear out owing to simple age. I bought a pair of fantastic BOSE ear phones, which included ambient sound suppression, back in the 1990s, so this head set is roughly 20+ years old. I pulled them out to listen to a great video by a dude exploring Macchu Piccu with his equivalent to a sensearound setup on is internet show: BETTER EVERY DAY. Well, I've mentioned that and may as well provide the link, because if you are interested in the INCA civilization, this is an incredible documentary.

A personal tour of Machu Picchu with surround sound super audio; the host is wearing a Gopro camera and exquisite microphones.  You will want to watch this wearing stereo headphones and you will think you are there.  Incredible tour, step by step, of the city. Close up views of all the architecture and details of this phenomenal citadel in the mountains.

https://www.youtube.com/watch?annotation_id=annotation_868785&feature=iv&src_vid=kfLH5_RWZH4&v=S0uGsAksBaY

[Tom Atwood]

Anyhow, the BOSE headset plastic literally had rotted and crumbled apart in my hands. I could not believe that plastic could degrade and rot like this!  Live and learn.

Tom Atwood

Executive Director, The National Robotics Education Foundation, www.The-NREF.org
Director, AUVSI Florida Peninsula Chapter, www.auvsi.net/floridapeninsulachapter/home
Founding Editor and Editor-in-Chief, Robot magazine, 2006 – 2014, www.botmag.com
Co-founder and Associate Publisher, Flight Journal magazine, 1996-2002, www.flightjournal.com

[Juanito Co]

If lasttime you used it and it was working,  the servo motor should be still working.  If the gears worn out, you would have grinding noise. Is the motor humming?  Are your running Arduino?  Check all you jumper cablles for continuity. Is it 5v or 12v? Did you burn it with wrong voltage? You need to share more info.  Can you open it and safely put it back.

[anthony witcher]

Hello Everyone,

The servo motors on my Anthony Bot are attached with a double sided foam tape to the wooden flat frame. I didn't want to tear them off for several reasons. I was more interested in testing my sonars system. So I unhooked the wires from the old servos and hooked them to the new servos that was temporarily fastened to the old servos.

As it turned out, the new servos were doing the same thing as the old ones. I went back to comment out some programming lines. Surprisedly, the sonar system was messing up programming to the servos from my point of view. After I comment out the sonar programming lines, the servos ran fine. When I unhooked the wires back to the old servos, they ran just like new.

Now the servos are not the problem. I am wondering if the Ultrasonic Ranger, SRF05, which I had on my robot is degraded. I tested several other of my SRF05 which I bought at the same time years ago are indicating that they are no good, like Atwood was saying, materials can degrade or become brittle whether you use it or not.

I'm planning to hook up the SRF05s to scopes soon.

I think this is an interesting topic. I am learning that when I take my old robots off the shelf after they have been sitting there for years, suddenly don't work like they should to be.

I remember seeing lots of robot movies where old robots get fired up after collecting many years of dust suddenly act like new. I would say that is a joke.

Anthony