stepper motor

On Sat, 12 Mar 2011 23:52:01 -0800 (PST), Roshan Nagekar


Projects like this always work out *so* well. Read and understand the
material at <http://www.cs.uiowa.edu/~jones/step/>  first.

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Rich Webb     Norfolk, VA

hey Rich thanks for the reply
can u share any such link which could explain this stuff to me in a
layman's language?

On Sun, 13 Mar 2011 06:03:54 -0700 (PDT), Roshan Nagekar


That site pretty much is, at least if you're considering designing your
own controller. An alternative would be something like
<http://www.robotshop.com/cytron-3-40v-2a-unipolar-bipolar-stepper-motor-controller.html>

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Rich Webb     Norfolk, VA

Roshan, that link is about as close to "layman's language" as you can get
and still explain how stepper motors work and how to use them.  If it's
over your head, then you probably don't have the background you need to
design and build your own robot from scratch.  You might try to get one of
the simple programmable robot kits like the Lego Mindstorms or VEX and
built your robot from that instead.  You don't need any real background in
electrical engineering to work with kits like those.

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

Firstly, you need two motors on a robot platform put side by side
or a car arrangement with one driving motor plus a steering linkage
turned by motor.
Anyway, you need two motors.

Stepper motors are recommended only if your load stays contant (one
constant weight)
and you are not going to support external disturbances (hitting a wall
or moving on uneven terrain)
If you are not a good electronic hobbyist, I suggest you buy the
stepper motor driver as proposed from Roboshop.

Otherwise, if your load is changing, stepper motors are not good and
servo motors are needed with a sensor measuring position like a
potentiometer (to keep it simple).
But then you need to close a speed control loop which means some
feedback control knowledge.
Again Roboshop is good place to look for equipment.

Turning into a spiral will require some knowledge of geometry.
You need to get those two motors to turn at different speed then the
robot turns into a circle.
Try this first.

Then try a spiral: one motor has to keep its speed constant and the
other
has to gradually change its speed from 0 to a certain maximum being
lower or equal than the other
then, the radius of rotation of your motion will become larger and
larger.
You just need to adjust the speed update in order to adjust the
radius.
You can try to calculate that but trial an error can do as well.

Bests

LHR