🚀 go-pugleaf

markh@csd4.csd.uwm.edu (Mark William Hopkins) writes:

>   I'm not very familiar with robotics in general, but keep seeing stepper
>motors mentioned in this context.  How fundamental are stepper motors,
>especially in relation to the issue of precision in speed and positioning?

There's a big difference between "normal" motors and stepper motors:

The function of a "normal" motor is to turn around while getting current.
For example to turn around one time it must get 1 second. To get a half
round it must 1/2 second and so on. To get an exact round-partition you
need a very exactly time-generator. But there's a next problem: The turn-
around-time depend of the weight of the moved thing by motor. If the
motor move empty a round takes for example 1 sec. If there is a big work
to do it take a lot more for example 2 sec. Because of this a exact
move isn't possible with different weights.

A stepper motor don't depend of time: For example a 4-bit motor: it has
5 lines having these functions:
the first is only ground;
the following 4 are the direction-bit. If you put current to the first one
the motor turns a little turn-partition; it's equal how long there is current
it makes always the same turn-partition.
To turn again you now must put current at the second bit. It now will
make a second turn-partition. To turn again you must put current at
the third on, to turn again you must put current at the fourth one
and after that to turn again you must put current at the first bit again.
The partition-number depends of the quality of the stepper motor. There
are for example 360-part-motors, so you must put current 360 times at the
right bits. So they work exactly and can be used in robotic.

- Frank -
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