LinuxCNC S-Curve Accelerations

I can not test that as it requires EtherCat hardware.

Hi Pcw,

The referred config file is a simulation for use with no hardware. 
I thought if this runs ok on your pc, maybe you have a idea why it will not run ok on real hardware.

i have it running with huge ferror values.





 

PCW wrote:

I can not test that as it requires EtherCat hardware.

I think you could just create a normal pncconf config for your hardware and set the ini file tpmod etc to use the scurve planner.
Once configured Linuxcnc does not care if its Ethercat or mesa.

I looked at the sim config an edited a mesa config to add the new TP, but it does
show major acceleration spikes (~500K)  lasting 1 servo period. I needed to set
large  following error limits  to avoid the spike triggering a following error.

Note that this is not hardware related but may have a relation to scaling so I can try again
by modifying the sim config to make sure everything else remains the same.
 

it worked on my Delta B3 Ethercat servos using CIA402/CSP config (see attachment).
i used linuxcnc-scurve-compat  from codeberg.

S-Curves would be nice.

Constant acceleration causes machine wobble.

OK it does work, my test configuration was missing the
default/max velocity and accel settings in the TRAJ section
of the .ini file. This (missing values) seems to work with the
standard TP (maybe it has some kind of working defaults)
but fails with  the S-Curve TP.

Note that I can still trigger following errors with actual
hardware as  the S-Curve TP does not seem to obey joint
acceleration constraints.

The TRAJ and joint accelerations are both set to 200 here:

 

But that acceleration is exceeded (and trips a following error when
it exceeds the hardware's accel limit of 240)

Pcw,

Thanks again for your effort.

What do you advise at this moment?
You can tune the planner with scurve jerk value in the hal section. This changes the accelation profile.
This jerk value is not integrated to the .ini file so far.

I assume you could tune your ini config to run without following error? Or is this not the case?

Indeed if you set acceleration to 200, the scurve max acceleration will be 400 at inflection point.
Exceeding your max acc off 240.

Indeed if you set acceleration to 200, the scurve max acceleration will be 400 at inflection point.
Exceeding your max acc off 240.

I will try this, note that this is a difference from LinuxCNCs standard TP where the
acceleration bound in the ini file is obeyed at all points.
(unless you have backlash compensation enabled)

acceleration = floor(max_acc/2)