Re: [CAD_CAM_EDM_DRO] Digest Number 2256
Posted by
Ray Henry
on 2002-04-22 06:46:18 UTC
Paul
You've gotta think dumber than that. There are no ramps or anything else.
This board just takes pulse rate signals from the PC parport and spits them
out as a set of up to four nicely formed pulse trains. Then it counts them,
or counts the pulses from an encoder and returns that number to the PC.
If you want trapezoidal, S-curve, or any other shaped ramping you can do that
with the PC by asking it to send a different set of rate commands over time.
The larger issue that you may be hinting at is that the communication with
this board is in descrete chunks and between these chunks, the board runs
descrete velocities. As a result, a motor will accelerate in velocity steps
like a staircase rather than a nice smooth curve like some old banisters.
But after all we are talking about stepper motors here and while you could
theoretically spin a stepper with a stereo audio amp to which you have
attached two analog frequency generators running 90 degrees out of phase with
each other to make continuously variable velocity -- I suspect that it is not
a practical thing to do. (My freshman English teacher would be appalled --
diagram that!)
HTH
Ray
You've gotta think dumber than that. There are no ramps or anything else.
This board just takes pulse rate signals from the PC parport and spits them
out as a set of up to four nicely formed pulse trains. Then it counts them,
or counts the pulses from an encoder and returns that number to the PC.
If you want trapezoidal, S-curve, or any other shaped ramping you can do that
with the PC by asking it to send a different set of rate commands over time.
The larger issue that you may be hinting at is that the communication with
this board is in descrete chunks and between these chunks, the board runs
descrete velocities. As a result, a motor will accelerate in velocity steps
like a staircase rather than a nice smooth curve like some old banisters.
But after all we are talking about stepper motors here and while you could
theoretically spin a stepper with a stereo audio amp to which you have
attached two analog frequency generators running 90 degrees out of phase with
each other to make continuously variable velocity -- I suspect that it is not
a practical thing to do. (My freshman English teacher would be appalled --
diagram that!)
HTH
Ray
> From: "Paul R. Hvidston" <paulh@...><S>
> Subject: Universal Stepper, Formerly: Re: Re: Brushless servo drive - Cheap
> Solution?????
>
> Jon,
>
> I'm confused ( no surprise there ;-) ). Does your board simply output
> independent channels of step pulses, possibly with trapezoidal accel/decel?
> If so how does it handle curved paths? Hopefully I'm missing something
> here.