Following error - Rotary Axis

More
07 May 2022 21:39 - 07 May 2022 21:40 #242268 by Slaybaw
I'm getting a following error on Joint 4 (A Axis) when running the following section of gcode on my fixed gantry machine + rotary axis.

I've read through myriad of threads and I can't figure out how to fix it!  Any help would be greatly appreciated.

INI and HAL files attached.

Gcode:
I get a following error on the line that starts with G1 A-720.
G93
G1 A0.00 F21.8
G1 Z13.37 A-29.65 F345.1
G1 Z12.50 A-70.17 F234.8
G1 Z11.00 A0.00 F135.6
G1 A-360.00 F26.4
G1 Z10.43 A-393.88 F384.3
G1 Z10.00 A-419.54 F472.0
G1 Z9.00 A-360.00 F203.4
G1 A-720.00 F33.6
G0 Z29.04
G94
Attachments:
Last edit: 07 May 2022 21:40 by Slaybaw.

Please Log in or Create an account to join the conversation.

More
08 May 2022 01:47 #242284 by Slaybaw
Few more details that may be important - this is a machine with open loop steppers...from other threads I've read...2 things cause following error message:

1) Stepgen velocity and stepgen accel not having enough "headroom" over the axis valuse
2) The base thread rate not actually being able to make all the requested pulses.

But I think I'm good on this front? My Base_Thread = 50000ns, which should allow for 10000 steps/sec....well above what my ini files specify.

Please Log in or Create an account to join the conversation.

More
08 May 2022 14:28 #242303 by PCW
Replied by PCW on topic Following error - Rotary Axis
You should not have a base thread at all with a Mesa configuration...

Please Log in or Create an account to join the conversation.

More
08 May 2022 18:49 - 08 May 2022 19:44 #242316 by Slaybaw
Right - yep, agree. After doing some pretty good searching over the last couple days, I found that BASE_PERIOD does nothing on Mesa configs. If you look at the HAL config, nothing is tied to the base thread anyway, so I don't think it had any effect.

Anyway, I remove the BASE_PERIOD from the .ini today, and tried again, and I still get a following error on Joint 4 at the same place in the G-code file.

Anything else I can try and scope to try and figure this out?  Do my FERROR and MIN_FERROR values look good in the .ini?  I can't even figure out where those values play in as I can't find those params referenced in the HAL file.

Updated INI and HAL files attached.

This is what halscope shows right when the following error occurs:
 
Attachments:
Last edit: 08 May 2022 19:44 by Slaybaw. Reason: Add'l clarity added.

Please Log in or Create an account to join the conversation.

More
09 May 2022 19:07 #242403 by Slaybaw
Updating here for posterity...I guess it really was as simple as an update to the STEPGEN_MAXVEL and STEPGEN_MAXACCEL values.

This fixed the issue immediately.

Before:
STEPGEN_MAXVEL = 450
STEPGEN_MAXACCEL = 1250

After:
STEPGEN_MAXVEL = 600
STEPGEN_MAXACCEL = 1500

 
Attachments:

Please Log in or Create an account to join the conversation.

More
09 May 2022 19:22 - 09 May 2022 19:23 #242405 by PCW
Replied by PCW on topic Following error - Rotary Axis
The original values in the ini file should be OK
(stepgen velocity and accel values are 25% > than
the joint/axis limits)

Can you plot the joint velocity along with the following
error (with the original ini file values) to see
what's gone wrong?
Last edit: 09 May 2022 19:23 by PCW.

Please Log in or Create an account to join the conversation.

More
09 May 2022 19:39 #242406 by Slaybaw
Thanks for the note - I am interested in troubleshooting more just to learn more...

I'll do some more testing this evening and report back.

Please Log in or Create an account to join the conversation.

More
10 May 2022 01:04 #242446 by Slaybaw
Here's a plot with joint.4.vel-cmd as well...that was the only signal I could find that was joint velocity.

 
Attachments:

Please Log in or Create an account to join the conversation.

More
10 May 2022 01:12 - 10 May 2022 01:12 #242447 by Slaybaw
Same plot, but with:
STEPGEN_MAXVEL = 600
STEPGEN_MAXACCEL = 1500

 
Attachments:
Last edit: 10 May 2022 01:12 by Slaybaw.

Please Log in or Create an account to join the conversation.

More
10 May 2022 01:56 - 10 May 2022 02:00 #242453 by PCW
Replied by PCW on topic Following error - Rotary Axis
If you look at the slope of the velocity,
the acceleration on the fast velocity downslope
exceeds 1500 deg/s^2, causing the increasing
following error because the stepgen is not allowed
to accelerate beyond 1500 deg/s^2.

So this seems like a trajectory planner or ini setup issue.
Last edit: 10 May 2022 02:00 by PCW.
The following user(s) said Thank You: Slaybaw

Please Log in or Create an account to join the conversation.

Time to create page: 0.205 seconds
Powered by Kunena Forum