looking for THE dc drive motor speed controller solution

Hi JCD,

pogo wrote:

When you use an H-Bridge to drive a permanent DC motor, you use PWM.
There are a couple of different types of drives (signed magnitude, or
locked anti-phase).

With signed magnitude, you have two control lines, one is normally used
as direction and one is normally used as the PWM control signal. The
percentage of on time (or off-time depending on the direction) in the
PWM signal controls the speed.

With locked-antiphase, a single control line is used. 50% duty cycle
means stopped. Greater than 50% means move in one way, and less than
50% means move in the other.

RC servos also use PWM, but quite differently. With a servo, the width
of the pulse typically vaires from 1 millsecond to 2 milliseconds. The
spacing between the pulses is less crictical and typically about 50
pulses per second are sent out. A 1 millisecond pulse tells the servo
to move to one extreme, and a 1.5 millsecond pulse tells it to go to
the middle, and a 2 millisecond pulse tells it to go to the other
extreme.

RC servos often contain a permannent DC motor (at least on the
inexpensive servos). You can remove all of the servo electronics,
connect the motors up to an H-Bridge and drive the motors just like
regular motors.


You'll probably need one a servo controller to drive the servos and an
H-Bridge to drive the DC gear motors.

Dave Hylands

correctly)

way ---

great!

Thanks for the great explanation! This one goes in my notes folder
!
Thanks again.
JCD

Try here... This might be what you need.  Good luck.

http://www.robotshop.ca/home/products/robot-parts/electronics/servo-controllers/solarbotics-l293d-motor-driver-kit.html

http://www.robotshop.ca/home/products/robot-parts/electronics/servo-controllers/solarbotics-l293d-motor-driver-kit.html
Close, but not enough amperage for my needs. (which I didn't put in
the specs, either)
Thanks though ! Good stuff there ....
JCD

Its a little more than $100, but the serializer from
http://www.roboticsconnection.com/  will handle 2 dc motors and a couple
servos, as well as sensors, and you talk to it via the serial port.
Ringo

Robert Davidson wrote:

http://www.robotshop.ca/home/products/robot-parts/electronics/servo-controllers/solarbotics-l293d-motor-driver-kit.html

Hey that looks slick! I'm not crazy about being limited to .Net to
use their provided libraries, but I have an email in to thier tech
support regarding that. But, yeah, I can handle more than $100 if
one product takes the place of 2 or more others! Since it's serial
I assume I can access/control everything regardless of libraries as
long as I send/receive the correct commands with the right
protocol. Of course, now I will examine the downloaded manual
*after* I have written all of this.

But I did want to say Thanks !
JCD

the .NET is just there if you want to use it. Anything that can spit
out serial can talk to it, 232 or TTL.


pogo wrote:

Thanks Ringo. Do you used to go to BotLanta (AHRC) ? Seems like I
recall your name.
Anyway, thanks again !
JCD

Yep, Still do.
Ringo

pogo wrote:

You might get a servo control chip and a PWM chip from below and
put them on a single small board. The bottom link shows how
simple a servo control setup can be. For the PWM control of
motors you would probably need some high current MOFET
transistors in an H-bridge to rapidly turn on/off the current to
the motor.

http://www.kronosrobotics.com/xcart/customer/home.php?cat )2
http://www.geocities.com/zoomkat/ezservo.htm

What you're asking for is exactly one of the uses our 'Pod's boards were
intended for. The DSP processor in the our 'Pod's were designed
specifically with motor control in mind, and do the job very well.

The IsoPod(TM) for <$100 has 12 PWM outputs, and 14 timer lines.
Configure them to be RC Servo PWM style signals, and you can control 26
RC Servos at once.

Or configure one PWM module (six lines) to control real DC motors, and
control 1 (BDCM), 2 (Complimentary with enable), 3 (Complimentary), or
(Independent with Locked AntiPhase) 6 motors. Still have 20 outputs
available for RC Servo control.

Or with the PWM module as above, do two motors, and use quadrature feed
back (loose 4 timer lines) and have have two closed PID loops. So you
can do two beautifully controlled DC motors, and still have 16 RC Servos
controlled as well.

Plus the language in the 'Pod's is interactive. Send command from the PC
host via serial, or USB (we've got USB versions of the 'Pod's as well).

If anything, our 'Pod's are so good for motion control, and have so many
options... it's hard to get people to understand the power they've got.
Pair up our 'Pod's with our H-bridges, and just a little bit of software
(we show lots of examples) and you really do have THE dc drive motor
speed controller solution, par excellance!

Sorry to sound like a commercial, but this is exactly what I meant for
these boards I designed to be used for. I'd be very pleased so see
everyone come to understand how good they are at motion control.

--
Randy M. Dumse
www.newmicros.com
Caution: Objects in mirror are more confused than they appear.

Where exactly are the many examples you mention on your website ?

Also, regarding the pods, it looks like after I buy I Pod then I
also have to buy additional software to do any programming. Is that
correct or have I glossed over things too quickly ? ( I tend to do
that, so please feel free to correct me! )

Thanks -
JCD

For the full blown PID example, go to our 'Pod's Downloads page. In the
appnotes - Example programs shows actual code from a contest winning
robot, also including Odometry.

There are quite a few RC Servo control examples there too.


Nothing extra required. 'Pod's come with IsoMax(TM) installed, and
Small C available for free download. There are third party full
development languages available, but really, we prefer our IsoMax(TM)
over any of those.

?

IsoMax(TM)

Thanks !

I'll be taking a long look !
JCD

I don't work for them, but I do like the 'Pods.

I also admit that they have a pretty bad website. I think that
if Randy put the information that he gives us here on his website
then there would be fewer questions.


Iso-Max (a Forth dialect with some interesting extensions) is
included. This is a nice programming environment.
--
D. Jay Newman           ! Author of:
jay@sprucegrove.com     ! _Linux Robotics: Programming Smarter Robots_
http://enerd.ws/robots/  ! "Heros aren't born, they're cornered."

I'll agree on that! Might not be a bad idea to scrape some threads off here and
post in a Q&A !
Randy has been a big help to me here in this group before I even ordered
anything from them !

JCD

nobody seems to have mentioned the osmc

http://www.robotpower.com/products/osmc_info.html

you can build it yourself, we have.

  dan

pogo wrote:

Just took a look at it. Also surfed over to the Scorpion XL page ... now *that*
might be exactly what I need !
Thanks !
JCD