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Posted by Thomas Arundel on October 12, 2005, 6:56 pm
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We're thinking of designing and manufacturing some servos aimed at the
robotics hobby market, with 360 degree rotation and feedback provided via an
optical encoder - target prices about $20-25 each using miniature precision
motor / gearbox combos similar to these:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=6005416519&rd=1&sspagename=STRK%3AMESE%3AIT&rd=1
That we're now starting to import from Asia. As well as traditional PWM
encoding, we could also consider encoding schemes like i2c. We're planning
on designing some even smaller models based around mobile phone / pager
vibrator motors.
It would seem that many people use RC servos, though there seem to be some
compromises, and I think we can improve on weight and torque as well as
offering arbitrary positioning.
I'd appreciate some thoughts, about the shortcomings of RC servos, and on
which areas we should focus to design a servo that's better for building
robots...
Also, does anyone know of any linear servos? Do you think those would be a
popular product, and if so in what sort of size / configuration?
Cheers,
Tom.
--
Thomas Arundel
TL: +44 (0) 1932 252482
FX: +44 (0) 870 137 6005
EM: tom@fastcomponents.co.uk
-----------------------------------------
Fast Components Limited
www.fastcomponents.co.uk
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Posted by steamer on October 13, 2005, 11:38 am
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--Small is cute, but spare a little of your talent to design
some robust stuff for "real world" bots please! :-)
--
"Steamboat Ed" Haas : A greasy donut, a cup of
Hacking the Trailing Edge! : coffee and thou...
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---
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Posted by Thomas Arundel on October 13, 2005, 7:20 pm
Please log in for more thread options > --Small is cute, but spare a little of your talent to design
> some robust stuff for "real world" bots please! :-)
Hmm I'm starting to think that a retrofit board that converts geared motor
units into precision servos might be more marketable and useful product,
than a unit reliant on one particular size of motor / geartrain...
What sort of sizes and specs are you thinking of?- we can source much larger
gearboxes too - high quality metal geartrains... :-)
--
Thomas Arundel
EM: tom.SPAMINACAN@fastcomponents.co.uk
-----------------------------------------
Fast Component sets - the best way to buy components!
www.fastcomponents.co.uk
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Posted by steamer on October 13, 2005, 8:23 pm
Please log in for more thread options : Hmm I'm starting to think that a retrofit board that converts geared motor
: units into precision servos might be more marketable and useful product,
: than a unit reliant on one particular size of motor / geartrain...
--Neat.
: What sort of sizes and specs are you thinking of?- we can source much larger
: gearboxes too - high quality metal geartrains... :-)
--Well I'm partial to those $20.- windshield wiper motors with the
built in gearbox, just cuz they've got lotsa torque and they're easily
obtainable from several surplus dealers..
--
"Steamboat Ed" Haas : A greasy donut, a cup of
Hacking the Trailing Edge! : coffee and thou...
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---
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Posted by Gordon McComb on October 13, 2005, 1:16 pm
Please log in for more thread options Speed-wise I think you need to go no less than 1 rps. These motors are a
bit too slow; the exporter ought to be able to supply some other gear
ratios. I know there is a market for small motors for micro and nano
robots, but I think it's a less significant market than desktop robots
that use standard servos. If anything, people tend to ask for servos
that are beefier and faster that the typical Futaba S-148 (or knockoff).
That makes the target >1 rps, and >56 oz-in (at 6vdc).
If you can manage the motor and optical encoder for $20-25 that would
place it at a competitive level with a $10 servo and a $10-15 (per side)
encoder setup, but not a jaw-dropping price. Remember that an R/C servo
doesn't need an H-bridge, so while control is not as precise as regular
PWM, there's less to design, and overall less cost. RC servos are
popular not so much because of their features, but because of their low
cost, plus ease of use.
Linear servos: I've seen retrofits for taking a standard servo and
making it linear, but unless you need the more precise movement, most
people just use a bell crank, and live with the (somewhat) non-linear
positioning.
-- Gordon
Thomas Arundel wrote:
>
> We're thinking of designing and manufacturing some servos aimed at the
> robotics hobby market, with 360 degree rotation and feedback provided via an
> optical encoder - target prices about $20-25 each using miniature precision
> motor / gearbox combos similar to these:
>
>
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=6005416519&rd=1&sspagename=STRK%3AMESE%3AIT&rd=1
>
> That we're now starting to import from Asia. As well as traditional PWM
> encoding, we could also consider encoding schemes like i2c. We're planning
> on designing some even smaller models based around mobile phone / pager
> vibrator motors.
>
> It would seem that many people use RC servos, though there seem to be some
> compromises, and I think we can improve on weight and torque as well as
> offering arbitrary positioning.
>
> I'd appreciate some thoughts, about the shortcomings of RC servos, and on
> which areas we should focus to design a servo that's better for building
> robots...
>
> Also, does anyone know of any linear servos? Do you think those would be a
> popular product, and if so in what sort of size / configuration?
>
> Cheers,
>
> Tom.
>
> --
> Thomas Arundel
> TL: +44 (0) 1932 252482
> FX: +44 (0) 870 137 6005
> EM: tom@fastcomponents.co.uk
> -----------------------------------------
> Fast Components Limited
> www.fastcomponents.co.uk
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> some robust stuff for "real world" bots please! :-)