double pid loop ?

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19 Jul 2016 01:53 - 19 Jul 2016 02:05 #77622 by vre
double pid loop ? was created by vre
I have ac servos 1.8kw that accept step-dir 500khz in position mode and analog -10+10v in velocity mode.
In position mode the drives have internal pid loop is possible to tune outer pid loop in linuxcnc ?
I mean with 2 pid loops 1 in drive and 1 in linuxcnc will be conflict between 2 pid loops ?

I made a simple breakout for 5i24 with 1 AM26LS31 & 1 AM26LS32 for testing in position mode with step dir
and possition feedback to linuxcnc but the operation is not stable i have some oscillation and delays to go in commanded possition
in last 0.05mm and some overshoot.
Is possible to pid tune in linuxcnc this setup or i must go for analog and have only one pid loop in linuxcnc and not in drive ?
Are there tutorials for tunning pid tunning for these 2 configs ?

Also if i get one 7i33TA for analog driving in speed mode how can i connect the spindle because pwm outputs from 7i33
are -10v +10v and my vfd for spindle gets 0-10v and has 2 pins for cw and ccw.Must make a new breakout that convert -10v +10v
to 0-10v CW CCW ?
7i33TA cooperates with 5i24 SVST4_8 firmware ?
Last edit: 19 Jul 2016 02:05 by vre.

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19 Jul 2016 02:31 #77623 by PCW
Replied by PCW on topic double pid loop ?
It should be possible to tune the 2 PID loops
Note that most of the tuning will be with FF1

a 7I33 will work with 0-10 just fine, you just dont supply negative PWM values
(motion has a absolute spindle speed pin that can be used for this)

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19 Jul 2016 02:45 - 19 Jul 2016 03:12 #77624 by vre
Replied by vre on topic double pid loop ?
Are there pid tuning tutorials for both speed and position mode ?
With 7i33 i undestand can output 0-10V but can output the ccw cw signals ?

i have tested now with P=1 FF1=1 others=0 and does not overshoot does not oscillate but delays to travel the last 0.05mm-0.005mm
Last edit: 19 Jul 2016 03:12 by vre.

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19 Jul 2016 13:54 - 19 Jul 2016 13:54 #77645 by PCW
Replied by PCW on topic double pid loop ?

Are there pid tuning tutorials for both speed and position mode ?
With 7i33 i undestand can output 0-10V but can output the ccw cw signals ?


No, but you can use other I/O pins for this (and motion provides spindle forward and spindle reverse hal pins to drive the I/O)

i have tested now with P=1 FF1=1 others=0 and does not overshoot does not oscillate but delays to travel the last 0.05mm-0.005mm


Note that FF1=1 will only work if the input and output scale are both in machine units, is this the case?

can you post your hal/ini files here?
Last edit: 19 Jul 2016 13:54 by PCW.

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19 Jul 2016 17:07 - 19 Jul 2016 17:11 #77659 by vre
Replied by vre on topic double pid loop ?
this is a test config look only Z axis
1mm/revolution
# Generated by PNCconf at Tue Jul 19 02:19:23 2016
# If you make changes to this file, they will be
# overwritten when you run PNCconf again

[EMC]
MACHINE = test1
DEBUG = 0

[DISPLAY]
DISPLAY = axis
POSITION_OFFSET = MACHINE
POSITION_FEEDBACK = ACTUAL
MAX_FEED_OVERRIDE = 2.000000
MAX_SPINDLE_OVERRIDE = 1.000000
MIN_SPINDLE_OVERRIDE = 0.500000
INTRO_GRAPHIC = linuxcnc.gif
INTRO_TIME = 5
PROGRAM_PREFIX = /home/labros/linuxcnc/nc_files
INCREMENTS = 5mm 1mm .5mm .1mm .05mm .01mm .005mm
LATHE = 1
POSITION_FEEDBACK = ACTUAL
DEFAULT_LINEAR_VELOCITY = 16.666667
MAX_LINEAR_VELOCITY = 32.500000
MIN_LINEAR_VELOCITY = 0.000000
DEFAULT_ANGULAR_VELOCITY = 0.250000
MAX_ANGULAR_VELOCITY = 1.000000
MIN_ANGULAR_VELOCITY = 0.010000
EDITOR = gedit
GEOMETRY = xyz

[FILTER]
PROGRAM_EXTENSION = .png,.gif,.jpg Greyscale Depth Image
PROGRAM_EXTENSION = .py Python Script
png = image-to-gcode
gif = image-to-gcode
jpg = image-to-gcode
py = python

[TASK]
TASK = milltask
CYCLE_TIME = 0.010

[RS274NGC]
PARAMETER_FILE = linuxcnc.var

[EMCMOT]
EMCMOT = motmod
COMM_TIMEOUT = 1.0
COMM_WAIT = 0.010
SERVO_PERIOD = 1000000

[HOSTMOT2]
# **** This is for info only ****
# DRIVER0=hm2_pci
# BOARD0=5i24

[HAL]
HALUI = halui
HALFILE = test1.hal
HALFILE = custom.hal
POSTGUI_HALFILE = postgui_call_list.hal
SHUTDOWN = shutdown.hal

[HALUI]

[TRAJ]
AXES = 3
COORDINATES = X Z
LINEAR_UNITS = mm
ANGULAR_UNITS = degree
CYCLE_TIME = 0.010
DEFAULT_VELOCITY = 3.25
MAX_VELOCITY = 32.50

[EMCIO]
EMCIO = io
CYCLE_TIME = 0.100
TOOL_TABLE = tool.tbl

#********************
# Axis X
#********************
[AXIS_0]
TYPE = LINEAR
HOME = 0.0
FERROR = 10.0
MIN_FERROR = 1.0
MAX_VELOCITY = 32.5
MAX_ACCELERATION = 750.0
# The values below should be 25% larger than MAX_VELOCITY and MAX_ACCELERATION
# If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger.
STEPGEN_MAXVEL = 40.62
STEPGEN_MAXACCEL = 937.50
P = 50.0
I = 0.0
D = 0.0
FF0 = 0.0
FF1 = 1.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 0.0
# these are in nanoseconds
DIRSETUP   = 1500
DIRHOLD    = 1500
STEPLEN    = 1500
STEPSPACE  = 1500
STEP_SCALE = 10000.0
MIN_LIMIT = -400.0
MAX_LIMIT = 400.0
HOME_OFFSET = 0.0

#********************
# Axis Z
#********************
[AXIS_2]
TYPE = LINEAR
HOME = 0.0
FERROR = 50.0
MIN_FERROR = 10.0
MAX_VELOCITY = 32.5
MAX_ACCELERATION = 1000
# The values below should be 25% larger than MAX_VELOCITY and MAX_ACCELERATION
# If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger.
STEPGEN_MAXVEL = 40.62
STEPGEN_MAXACCEL = 1250
P = 1.0
I = 0.0
D = 0.0
FF0 = 0.0
FF1 = 1.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 0.0
ENCODER_SCALE = 10000.0
# these are in nanoseconds
DIRSETUP   = 1500
DIRHOLD    = 1500
STEPLEN    = 1500
STEPSPACE  = 1500
STEP_SCALE = 10000.0
MIN_LIMIT = -1000.0
MAX_LIMIT = 1000.0
HOME_OFFSET = 0.0

#********************
# Spindle 
#********************
[SPINDLE_9]
P = 0
I = 0
D = 0
FF0 = 1
FF1 = 0
FF2 = 0
BIAS = 0
DEADBAND = 0
MAX_OUTPUT = 2000

# Generated by PNCconf at Tue Jul 19 02:19:23 2016
# If you make changes to this file, they will be
# overwritten when you run PNCconf again

loadrt trivkins
loadrt [EMCMOT]EMCMOT servo_period_nsec=[EMCMOT]SERVO_PERIOD num_joints=[TRAJ]AXES
loadrt hostmot2
loadrt hm2_pci config="firmware=hm2/5i24/SVST4_8.BIT num_encoders=1 num_pwmgens=0 num_stepgens=2" 
setp    hm2_5i24.0.watchdog.timeout_ns 5000000
loadrt pid names=pid.x,pid.z,pid.s

addf hm2_5i24.0.read          servo-thread
addf motion-command-handler   servo-thread
addf motion-controller        servo-thread
addf pid.x.do-pid-calcs       servo-thread
addf pid.z.do-pid-calcs       servo-thread
addf pid.s.do-pid-calcs       servo-thread
addf hm2_5i24.0.write         servo-thread

# external output signals

# external input signals

#*******************
#  AXIS X
#*******************

setp   pid.x.Pgain     [AXIS_0]P
setp   pid.x.Igain     [AXIS_0]I
setp   pid.x.Dgain     [AXIS_0]D
setp   pid.x.bias      [AXIS_0]BIAS
setp   pid.x.FF0       [AXIS_0]FF0
setp   pid.x.FF1       [AXIS_0]FF1
setp   pid.x.FF2       [AXIS_0]FF2
setp   pid.x.deadband  [AXIS_0]DEADBAND
setp   pid.x.maxoutput [AXIS_0]MAX_OUTPUT
setp   pid.x.error-previous-target true
setp   pid.x.maxerror .0005

net x-index-enable  <=> pid.x.index-enable
net x-enable        =>  pid.x.enable
net x-pos-cmd       =>  pid.x.command
net x-vel-cmd       =>  pid.x.command-deriv
net x-pos-fb        =>  pid.x.feedback
net x-output        =>  pid.x.output

# Step Gen signals/setup

setp   hm2_5i24.0.stepgen.01.dirsetup        [AXIS_0]DIRSETUP
setp   hm2_5i24.0.stepgen.01.dirhold         [AXIS_0]DIRHOLD
setp   hm2_5i24.0.stepgen.01.steplen         [AXIS_0]STEPLEN
setp   hm2_5i24.0.stepgen.01.stepspace       [AXIS_0]STEPSPACE
setp   hm2_5i24.0.stepgen.01.position-scale  [AXIS_0]STEP_SCALE
setp   hm2_5i24.0.stepgen.01.step_type        0
setp   hm2_5i24.0.stepgen.01.control-type     1
setp   hm2_5i24.0.stepgen.01.maxaccel         [AXIS_0]STEPGEN_MAXACCEL
setp   hm2_5i24.0.stepgen.01.maxvel           [AXIS_0]STEPGEN_MAXVEL

# ---closedloop stepper signals---

net x-pos-cmd    <= axis.0.motor-pos-cmd
net x-vel-cmd    <= axis.0.joint-vel-cmd
net x-output     <= hm2_5i24.0.stepgen.01.velocity-cmd
net x-pos-fb     <= hm2_5i24.0.stepgen.01.position-fb
net x-pos-fb     => axis.0.motor-pos-fb
net x-enable     <= axis.0.amp-enable-out
net x-enable     => hm2_5i24.0.stepgen.01.enable

# ---setup home / limit switch signals---

net x-home-sw     =>  axis.0.home-sw-in
net x-neg-limit     =>  axis.0.neg-lim-sw-in
net x-pos-limit     =>  axis.0.pos-lim-sw-in

#*******************
#  AXIS Z
#*******************

setp   pid.z.Pgain     [AXIS_2]P
setp   pid.z.Igain     [AXIS_2]I
setp   pid.z.Dgain     [AXIS_2]D
setp   pid.z.bias      [AXIS_2]BIAS
setp   pid.z.FF0       [AXIS_2]FF0
setp   pid.z.FF1       [AXIS_2]FF1
setp   pid.z.FF2       [AXIS_2]FF2
setp   pid.z.deadband  [AXIS_2]DEADBAND
setp   pid.z.maxoutput [AXIS_2]MAX_OUTPUT
setp   pid.z.error-previous-target true
setp   pid.z.maxerror .0005

net z-index-enable  <=> pid.z.index-enable
net z-enable        =>  pid.z.enable
net z-pos-cmd       =>  pid.z.command
net z-vel-cmd       =>  pid.z.command-deriv
net z-pos-fb        =>  pid.z.feedback
net z-output        =>  pid.z.output

# Step Gen signals/setup

setp   hm2_5i24.0.stepgen.00.dirsetup        [AXIS_2]DIRSETUP
setp   hm2_5i24.0.stepgen.00.dirhold         [AXIS_2]DIRHOLD
setp   hm2_5i24.0.stepgen.00.steplen         [AXIS_2]STEPLEN
setp   hm2_5i24.0.stepgen.00.stepspace       [AXIS_2]STEPSPACE
setp   hm2_5i24.0.stepgen.00.position-scale  [AXIS_2]STEP_SCALE
setp   hm2_5i24.0.stepgen.00.step_type        0
setp   hm2_5i24.0.stepgen.00.control-type     1
setp   hm2_5i24.0.stepgen.00.maxaccel         [AXIS_2]STEPGEN_MAXACCEL
setp   hm2_5i24.0.stepgen.00.maxvel           [AXIS_2]STEPGEN_MAXVEL

# ---closedloop stepper signals---

net z-pos-cmd    <= axis.2.motor-pos-cmd
net z-vel-cmd    <= axis.2.joint-vel-cmd
net z-output     <= hm2_5i24.0.stepgen.00.velocity-cmd
#net z-pos-fb     <= hm2_5i24.0.stepgen.00.position-fb
net z-pos-fb     => axis.2.motor-pos-fb
net z-enable     <= axis.2.amp-enable-out
net z-enable     => hm2_5i24.0.stepgen.00.enable

# ---Encoder feedback signals/setup---

setp    hm2_5i24.0.encoder.00.counter-mode 0
setp    hm2_5i24.0.encoder.00.filter 1
setp    hm2_5i24.0.encoder.00.index-invert 0
setp    hm2_5i24.0.encoder.00.index-mask 0
setp    hm2_5i24.0.encoder.00.index-mask-invert 0
setp    hm2_5i24.0.encoder.00.scale  [AXIS_2]ENCODER_SCALE

net z-pos-fb               <=  hm2_5i24.0.encoder.00.position
net z-vel-fb               <=  hm2_5i24.0.encoder.00.velocity
net z-pos-fb               =>  axis.2.motor-pos-fb
net z-index-enable    axis.2.index-enable  <=>  hm2_5i24.0.encoder.00.index-enable
net z-pos-rawcounts        <=  hm2_5i24.0.encoder.00.rawcounts

# ---setup home / limit switch signals---

net z-home-sw     =>  axis.2.home-sw-in
net z-neg-limit     =>  axis.2.neg-lim-sw-in
net z-pos-limit     =>  axis.2.pos-lim-sw-in

#*******************
#  SPINDLE S
#*******************

setp   pid.s.Pgain     [SPINDLE_9]P
setp   pid.s.Igain     [SPINDLE_9]I
setp   pid.s.Dgain     [SPINDLE_9]D
setp   pid.s.bias      [SPINDLE_9]BIAS
setp   pid.s.FF0       [SPINDLE_9]FF0
setp   pid.s.FF1       [SPINDLE_9]FF1
setp   pid.s.FF2       [SPINDLE_9]FF2
setp   pid.s.deadband  [SPINDLE_9]DEADBAND
setp   pid.s.maxoutput [SPINDLE_9]MAX_OUTPUT
setp   pid.s.error-previous-target true

net spindle-index-enable  <=> pid.s.index-enable
net spindle-enable        =>  pid.s.enable
net spindle-vel-cmd-rpm     => pid.s.command
net spindle-vel-fb-rpm      => pid.s.feedback
net spindle-output        <=  pid.s.output

# ---setup spindle control signals---

net spindle-vel-cmd-rps        <=  motion.spindle-speed-out-rps
net spindle-vel-cmd-rps-abs    <=  motion.spindle-speed-out-rps-abs
net spindle-vel-cmd-rpm        <=  motion.spindle-speed-out
net spindle-vel-cmd-rpm-abs    <=  motion.spindle-speed-out-abs
net spindle-enable             <=  motion.spindle-on
net spindle-cw                 <=  motion.spindle-forward
net spindle-ccw                <=  motion.spindle-reverse
net spindle-brake              <=  motion.spindle-brake
net spindle-revs               =>  motion.spindle-revs
net spindle-at-speed           =>  motion.spindle-at-speed
net spindle-vel-fb-rps         =>  motion.spindle-speed-in
net spindle-index-enable      <=>  motion.spindle-index-enable

# ---Setup spindle at speed signals---

sets spindle-at-speed true


#******************************
# connect miscellaneous signals
#******************************

#  ---HALUI signals---

net joint-select-a        halui.joint.0.select
net x-is-homed            halui.joint.0.is-homed
net jog-x-pos             halui.jog.0.plus
net jog-x-neg             halui.jog.0.minus
net jog-x-analog          halui.jog.0.analog
net joint-select-c        halui.joint.2.select
net z-is-homed            halui.joint.2.is-homed
net jog-z-pos             halui.jog.2.plus
net jog-z-neg             halui.jog.2.minus
net jog-z-analog          halui.jog.2.analog
net jog-selected-pos      halui.jog.selected.plus
net jog-selected-neg      halui.jog.selected.minus
net spindle-manual-cw     halui.spindle.forward
net spindle-manual-ccw    halui.spindle.reverse
net spindle-manual-stop   halui.spindle.stop
net machine-is-on         halui.machine.is-on
net jog-speed             halui.jog-speed 
net MDI-mode              halui.mode.is-mdi

#  ---coolant signals---

net coolant-mist      <=  iocontrol.0.coolant-mist
net coolant-flood     <=  iocontrol.0.coolant-flood

#  ---probe signal---

net probe-in     =>  motion.probe-input

#  ---motion control signals---

net in-position               <=  motion.in-position
net machine-is-enabled        <=  motion.motion-enabled

#  ---digital in / out signals---

#  ---estop signals---

net estop-out     <=  iocontrol.0.user-enable-out
net estop-out     =>  iocontrol.0.emc-enable-in

#  ---manual tool change signals---

loadusr -W hal_manualtoolchange
net tool-change-request     iocontrol.0.tool-change       =>  hal_manualtoolchange.change
net tool-change-confirmed   iocontrol.0.tool-changed      <=  hal_manualtoolchange.changed
net tool-number             iocontrol.0.tool-prep-number  =>  hal_manualtoolchange.number
net tool-prepare-loopback   iocontrol.0.tool-prepare      =>  iocontrol.0.tool-prepared
Last edit: 19 Jul 2016 17:11 by vre.

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19 Jul 2016 17:18 #77660 by PCW
Replied by PCW on topic double pid loop ?
For open loop stepgen (X currently) I would set P to 1000

For closed loop, can you not set P higher than 1 and remain stable?

(P=1 means a 1 mm error will cause a velocity adjustment of 1 mm/sec)

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19 Jul 2016 17:28 - 19 Jul 2016 17:28 #77662 by vre
Replied by vre on topic double pid loop ?
My config is ok for Z ?
if i set P=50 for Z oscillates & overshoots
Last edit: 19 Jul 2016 17:28 by vre.

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19 Jul 2016 17:31 - 19 Jul 2016 17:31 #77663 by PCW
Replied by PCW on topic double pid loop ?
Looks OK though a P of 1 is probably way too low

There's quite a range between 1 and 50.
You need to find the maximum stable P value for best performance
(this is no different on analog interfaces)
Last edit: 19 Jul 2016 17:31 by PCW.

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19 Jul 2016 17:39 #77664 by vre
Replied by vre on topic double pid loop ?
In what range must i set FF1 ?

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19 Jul 2016 17:41 #77665 by Todd Zuercher
Replied by Todd Zuercher on topic double pid loop ?
Did you follow the servo manufactures procedures for properly tuning the drives first?
Linuxcnc can't be expected to work properly with a position mode servo drive if the drive isn't properly tuned first.

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