PCNC770 4th Axis w/ Clear Path Servo & PathPilot
- charliebrumfield
- Offline
- New Member
-
Less
More
- Posts: 16
- Thank you received: 1
02 Jun 2016 16:53 - 02 Jun 2016 18:51 #75343
by charliebrumfield
PCNC770 4th Axis w/ Clear Path Servo & PathPilot was created by charliebrumfield
We slapped a giant Clear Path Servo from Technik on the 4th axis of our PCNC770. All was well while under Mach3 control but with the path pilot upgrade I can't seem to make the deceleration work quite right with interpolated moves and it's causing our 4th axis work to come out twisted. See video for details. Anyone have any idea what parameters I need to tweak? I'm not familiar with LinuxCNC or PathPilot yet so this one has me stumped.
also have a thread over at CNC Zone. you can see what I've already tried in this link.
http://http://www.cnczone.com/forums/tormach-personal-cnc-mill/309278-pcnc770-4th-axis-clear-path-servo-pathpilot.html#post1891948
Since the video was take we have set P = 50 and max_error=0 that has the decell issue solved but we are still getting twisted part.
thanks in advance,
charlie
also have a thread over at CNC Zone. you can see what I've already tried in this link.
http://http://www.cnczone.com/forums/tormach-personal-cnc-mill/309278-pcnc770-4th-axis-clear-path-servo-pathpilot.html#post1891948
Since the video was take we have set P = 50 and max_error=0 that has the decell issue solved but we are still getting twisted part.
thanks in advance,
charlie
Last edit: 02 Jun 2016 18:51 by charliebrumfield. Reason: adding link to cnc zone
Please Log in or Create an account to join the conversation.
02 Jun 2016 17:09 #75345
by andypugh
Replied by andypugh on topic PCNC770 4th Axis w/ Clear Path Servo & PathPilot
The PID is used to make the step generation more insensitive to real-time thread jitter.
Do you know what the servo-thread period is in that setup? I would assume a 2kHz serv-thread if the PGAIN is 500.
Given that this is a servo motor being sent position commands by step-dir I would be very tempted to remove the PID from that axis.
ie, connect axis.3.motor-position-cmd directly to the stepgen (this would be in the HAL file).
Do you know what the servo-thread period is in that setup? I would assume a 2kHz serv-thread if the PGAIN is 500.
Given that this is a servo motor being sent position commands by step-dir I would be very tempted to remove the PID from that axis.
ie, connect axis.3.motor-position-cmd directly to the stepgen (this would be in the HAL file).
The following user(s) said Thank You: charliebrumfield
Please Log in or Create an account to join the conversation.
- charliebrumfield
- Offline
- New Member
-
Less
More
- Posts: 16
- Thank you received: 1
02 Jun 2016 18:53 #75353
by charliebrumfield
Replied by charliebrumfield on topic PCNC770 4th Axis w/ Clear Path Servo & PathPilot
I was thinking it might be something related to the PID as there is already an encoder and controller built in to the clearpath system. i'll see if I can't figure out how to work the HAL file changes. (total noob when it comes to linuxcnc)
Please Log in or Create an account to join the conversation.
02 Jun 2016 19:09 #75354
by PCW
Replied by PCW on topic PCNC770 4th Axis w/ Clear Path Servo & PathPilot
Why dont you try setting the ferror limits to something reasonable first as I suggested in the CNCZone thread
This will tell you if you have a following problem or theres something else like Gcode differences, step polarity issues so steps are lost on reversals etc etc
This will tell you if you have a following problem or theres something else like Gcode differences, step polarity issues so steps are lost on reversals etc etc
The following user(s) said Thank You: charliebrumfield
Please Log in or Create an account to join the conversation.
- charliebrumfield
- Offline
- New Member
-
Less
More
- Posts: 16
- Thank you received: 1
02 Jun 2016 19:44 #75357
by charliebrumfield
Replied by charliebrumfield on topic PCNC770 4th Axis w/ Clear Path Servo & PathPilot
i'll try that. hadn't been back over to CNC Zone to see your reply yet. but honestly I haven't changed the ferror values those are stock tormach numbers. i'll check the CNC Zone thread now and test it out.
Please Log in or Create an account to join the conversation.
- charliebrumfield
- Offline
- New Member
-
Less
More
- Posts: 16
- Thank you received: 1
03 Jun 2016 01:12 - 03 Jun 2016 01:13 #75368
by charliebrumfield
Replied by charliebrumfield on topic PCNC770 4th Axis w/ Clear Path Servo & PathPilot
alright ran the settings you specified over at cnc zone
looks like I am getting a following error on joint 3 as soon as the axis starts to spin I've attached my .ini and .hal files.
[AXIS_3]
# default value for max velocity is 22.0 max accel 69.0 and scale 500
TYPE = ANGULAR
HOME = 0.0
MAX_VELOCITY = 125
MAX_ACCELERATION = 8000
# 20 % higher
STEPGEN_MAX_VEL = 149
STEPGEN_MAXACCEL = 9600
# jog shuttle ring speed
MAX_JOG_VELOCITY_UPS = 125
MIN_JOG_VELOCITY_UPS = 0.15
# nanoseconds
DIRSETUP = 10000
DIRHOLD = 10000
STEPLEN = 8000
STEPSPACE = 5000
# PID tuning params
DEADBAND = 0
P = 1000
I = 0
D = 0
FF0 = 0
FF1 = 0
FF2 = 0.00011
BIAS = 0
MAX_OUTPUT = 0
MAX_ERROR = 0.0005
SCALE = 200.0
FERROR = 0.1
MIN_FERROR = 0.01looks like I am getting a following error on joint 3 as soon as the axis starts to spin I've attached my .ini and .hal files.
Last edit: 03 Jun 2016 01:13 by charliebrumfield. Reason: fixing typo code
Please Log in or Create an account to join the conversation.
03 Jun 2016 02:39 #75375
by PCW
Replied by PCW on topic PCNC770 4th Axis w/ Clear Path Servo & PathPilot
The thread order in the hal file is wrong
addf hm2_5i25.0.write servo-thread
should be the last thing done (so the last addf)
addf hm2_5i25.0.write servo-thread
should be the last thing done (so the last addf)
The following user(s) said Thank You: charliebrumfield
Please Log in or Create an account to join the conversation.
- charliebrumfield
- Offline
- New Member
-
Less
More
- Posts: 16
- Thank you received: 1
03 Jun 2016 02:50 #75377
by charliebrumfield
Replied by charliebrumfield on topic PCNC770 4th Axis w/ Clear Path Servo & PathPilot
moved that line to the end of the servo thread. will run and report back.
by the way, not sure it I said this yet but, thanks for all the help.
by the way, not sure it I said this yet but, thanks for all the help.
Please Log in or Create an account to join the conversation.
- charliebrumfield
- Offline
- New Member
-
Less
More
- Posts: 16
- Thank you received: 1
03 Jun 2016 03:00 #75378
by charliebrumfield
Replied by charliebrumfield on topic PCNC770 4th Axis w/ Clear Path Servo & PathPilot
no bueno. updated the .hal file, still get a joint following error as soon as the a axis starts to rotate. this is still using this pid tuning set up
# PID tuning params
DEADBAND = 0
P = 1000
I = 0
D = 0
FF0 = 0
FF1 = 0
FF2 = 0.00011
BIAS = 0
MAX_OUTPUT = 0
MAX_ERROR = 0.0005
SCALE = 200.0
FERROR = 0.1
MIN_FERROR = 0.01Please Log in or Create an account to join the conversation.
03 Jun 2016 03:28 #75380
by PCW
Replied by PCW on topic PCNC770 4th Axis w/ Clear Path Servo & PathPilot
I would now try setting the max_error to 0
The following user(s) said Thank You: charliebrumfield
Please Log in or Create an account to join the conversation.
Moderators: cncbasher
Time to create page: 0.443 seconds