On Wed, 12 May 2010 00:36:19 +0100, Andy Pugh <[email protected]> wrote: > On 11 May 2010 22:52, Agustin Cruz <[email protected]> wrote: >> I'm trying to do rastering with a laser. >> But each time the pwm changes, the movement stops for a few milliseconds. >> If in the next pixel changes the pwm, then there is a slight pause. >> Is there any way to make rastering at a constant speed, with no pauses to >> change the pwm?. > > What does your G-code look like? > What form is your intensity information in? > > eg, if your G-code says things like > G1 X0 > S 200 > G1 X20 > S100 > G1 X25 > S150 > > etc then you might be able to smooth it out by relaxing the > accel/decel parameters or the trajectory accuracy > http://linuxcnc.org/docs/html/gcode_main.html#sub:G61,-G61.1,-G64 > > You could try running the servo thread faster too, I think a change to > PWM value has to wait for a servo thread (every mS by default)
The last time I needed something like this was in the context of running a 3D elastic backscattering LiDAR. One of the modes of operation was to move the LiDAR (picture a 2000 Watt laser pointer on a gimble mount with a 12ns pulse width) where were we moving the LiDAR at a constant velocity and triggering the laser to fire at synchronized way-points (thus generating a known 3D scanning volume). You could basically fake the same by co-opting one of the axes as a laser trigger and then programming in the trigger pulse as the step in the auxiliary axis. This is of course a total hack and you would likely have to write a code generator function which would take a list of your way-points, and their relative timings, and calculate a path. Depending on the specifics of your application you can simplify things a lot and write a generator in maybe a hundred lines of C or python code. The devil is definitely going to be in the details. Hope that helps. EBo -- ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
