tune stepper function

Hi,

A-axis is testable now. Thanks.

Test-Dialog accepts now new values, but I guess, that values will not be used at testing.
hal-show displays a velocity of 100 and 12,7 - which I guess are mm/s - so the speed is stil 6000, although the dialog shows different values.

Help page of axistest claims, that test run uses a trapezoidal velocity profile, but my ears don't believe that. It looks, as if the test starts with full speed (100) and after half of distance it switches to low speed (12,7).

Is there a way to really test trapezoidal velocity with the given acceleration parameters from dialog?
Help page of axistest does not name a pin related to acceleration.
Is the dialog value misleading?

I just tested the latest on my stepper machine.
It does use a trapezoidal profile.
It will go above 6000

Of course you must have the distance and acceleration high enough to allow it to get to the cruise phase.

To see for your self use halscope to watch the stepgen velocity feedback pin.
(This is simple_tp 's code if you want to look at it what plans the move)
github.com/LinuxCNC/linuxcnc/blob/master...nents/simple_tp.comp

BUT
I did occasionally see weird oscillations in halscope (I didn't run motors)
And i may have found the problem.
A long while ago Peter of Mesa told me to not connect a signal to PID.command-deriv. i removed them from the configure HAL code but missed the test.
if a signal is connected to it but no driving pin is use FF1 becomes useless and that is what keeps the stepgen track accurately - apparently.

I'll push the fix to remove it and maybe you can test again/

Chris

I just tested the latest on my stepper machine.
It does use a trapezoidal profile.
It will go above 6000

Of course you must have the distance and acceleration high enough to allow it to get to the cruise phase.

I don't run motor test on existing machine configurations.

I always start pncconf to build a new machine (by reading mesaoutput through help input page).
My A-axis is a geared rotary axis with a gear rate of 1:90 - so one turn should be long enuf for cruise phase.

hal-show of position has fast update rate, so I can see intermediate values.
So if a trapezoidal profile would be used, I expect intermediate values on feedrate too. But feedrate jumps from 100 to 12.7 and back (and some exponential values instead of zero).

Whatever I enter in the maxspeed combobox - velocity does not rise above 100
... and I can change acceleration to small values, but I don't see rampings in hal-show output.

I assume when you say hal-show you mean halmeter.
It matters because hal-show is used when testing a full configuration -leading me to wonder what you were testing with pncconf or the ful config.

I'll assume pncconf.
Halmeter does not really update very fast.

try HALscope - its right there.
set to rolling
pick stepgen.00.velocity-fb
adjust the gain till you see the shape

You should be able to tell me what the shape is rather then both of us guess why it doesn't seem right

Not sure how I can debug any further for you. I tested metric and imperial with a live mesa card it all seemed to work.
If you can adjust the spinboxes higher then 6000 then it should use the numbers.
Here again you can use halmeter to check to see if the velocity changes.
for instance HAL pin 'simple_tp.maxvel' (units per second) should track the spinbox (units per minute)

Finally - did you set maxoutput in the PID to a limitting setting ?
A setting of zero will let the PID have no limit.

Chris

cmorley wrote: I assume when you say hal-show you mean halmeter.

Hal show is on the "show machine configuration" menu and can monitor multiple pins or parameters at the same time, i use that all the time as can be seen on many screenshots on my posts.

I assume when you say hal-show you mean halmeter.

what ever - I only talk about windows created by pncconf.
I don't know, who creates the windows with title "hm2_5i24.0.stepgen.07.position-fb" and "hm2_5i24.0.stepgen.07.velocity-fb". I assumed, that some hal function created that window and the only hal function to show pins I know about is hal-show. I'm sorry, if that is wrong.
.


and the slow part of the test is this:
.


Anyway ...

its obvious to see, that Hal-Meter does not reflect the configured top-speed (beside the fact, that the value -6000 is anything but not speed rpm - right label would be something like degrees/minute).
"velocity-fb"- value of -100 will most probabely be mm/second.

None of the values is related to the topspeed of 12000 degree/minute.

by the way:
Hal oszilloscope is shown, but its impossible to select anything useful.


With an acceleration of 100 degrees/s² I was able to hear (and watch) the ramping.
Interestingly the acceleration is not steady/smooth - there is some break impuls during acceleration.
Opposed to that deceleration is steady/smooth.