servo board

http://www.seetron.com/ssc.htm

JM

John Mianowski åAF«E9�93ïBC�


really cool and thanks. But is there any thing can control the
"contingous servo"? i am using a "continugous servo" for the wheels.
thanks
from Peter

The servo control board doesn't know the difference. The software you
write will be simpler, as you know have only three modes for any motor:

1. Send 2 millisecond duration pulses every 20 milliseconds to go one
direction;
2. Send 1 millisecond duration pulses every 20 milliseconds to go the
other direction;
3. Don't send any pulses, and the motor will stop.

-- Gordon

As Gordon said, the continuous servos receive the exact same signal as the
normal server.  The difference is that it interprets the position
information as speed information.  A signal which makes a normal server
move to the center position is seen as a 0 speed for the continuous servo.
Positions on either side of that cause it to spin forward, or backwards, at
different speeds.  So any servo controller board will work fine for both
types of servos.  The commands simply translate to speed commands instead
of position commands.

With the Mini SSC II board (the first suggestion posted) you can't make it
stop sending pulses.  So you don't have a simple way with that board to
guarantee your servo is not moving.  If you set the center position with
your software, it should stand still, but this is not perfect because it's
an analog pulse width protocol that the board using to control the servos,
and the pulse width generated by the servo board for the center position
might not be the exact width needed to make it stand still.  So it's likely
to cause the servo to creep slowly.

Some of the more advanced boards posted in that second message give you the
ability to tell the controller to turn the servo off - which means it just
stops sending pulses as Gordon talked about above.  For controlling
continuous spinning servos, it would be good to get a board that allowed
you to stop sending pulses to the servo.  That can be a useful advantage
for normal servos as well because when you stop sending pulses to them,
they stop holding their position and can be moved to a different position
(though because of gearing it takes a bit of torque to move them).

--
Curt Welch                                            http://CurtWelch.Com/
curt@kcwc.com                                        http://NewsReader.Com/

Curt Welch åAF«E9�93ïBC�


thank you so much to teaching the newbie (me).
    I am going to develop an AI using my arm 7 development board to let
the robot walk by two legs. Is anybody here is doing the same thing?
    I need to make a "expand and contract" servo, which like the "oil
presure servo" works. i really can't find a tutorial website in google,
do you know any?
thanks
from Peter

cmk128@hotmail.com åAF«E9�93ïBC�


     do you have any website that talk about "very flexible movement"
robot?
thanks
from Peter (cmk128@hotmail.com)

    --What he said; and if you want to vary speed you just change the
numbers. It's possible to program rise and fall, to make motion more
"natural" too. I recall there's an exercise in the Parallax BOE-bot book
that describes various programming shortcuts to do this.

--
        "Steamboat Ed" Haas         :  Dedicated to Spinachio,        
        Hacking the Trailing Edge!  :  goddess of spinach..
                          www.nmpproducts.com
                   ---Decks a-wash in a sea of words---

Some serial servo controllers beyond the mini ssc-II.

http://www.pololu.com/products/pololu/#servcon
http://www.pontech.com/products/sv200/index.htm
http://www.servocity.com/html/servo_controllers.html