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More than 9 axes with servo

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8 years 2 months ago - 8 years 2 months ago #116077 by Ilya
More than 9 axes with servo was created by Ilya
Hello everyone
I have read this topic and as I understand it - I can't use M67 or M68 for pid

We are building a machine for processing logs, for this I need 11 axes and 12 motors.
A minimum of 6 interpolated axes (7 joints as the X-axis is gantry)
6 axes (XXYZABC) - for processing(engraving, milling, Etc)

5 axes will have to drive up to the right place and fix the log. It is necessary when you have to cut it in half.
They do not need to be interpolated, but they need to be able to manage them through both the MDI and the control program.

I use the servo Delta ASD-A2-E ethercat running, and LinuxCNC 2.8 pre~

I would appreciate any help and ideas
Thanks,
ilya
Last edit: 8 years 2 months ago by Ilya.

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8 years 2 months ago #116087 by Todd Zuercher
Replied by Todd Zuercher on topic More than 9 axes with servo
That topic doesn't say that at all.

First lets straighten you out on what an axis is in Linuxcnc. As of 2.8-pre the current Master development branch (before this the definition is somewhat muddled) an "axis" refers to a Cartesian coordinate in space, and is limited to X,Y,Z (linear), A,B,C (rotary), plus 3 additional linear U,V,W.

In Linuxcnc, Joints refer to the actual physical pieces of the machine that move the machine or each motor driving some part of the machine. I am not sure if these are or are not actually limited to only 9 in Master. (I haven't played with 2.8-pre much.) Joints are associated with and move the axis coordinates via the kinematic module that is loaded in the configuration.

A servo could also be commanded with a pid loop directly and not be associated with a joint or axis. This is what is being suggested by using M67 or M68 commands to change the postion command to the pid loop. Other components such as limit3 could (should) be used between the command input (M67/M68) and the pid to help control and smooth the motion created by the commands.

However I'm not sure that you would be using a pid loop in linuxcnc with those Eithercat drives? You might just be directly sending positioning commands directly to the drives and they would be handling the loops internally.
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8 years 2 months ago - 8 years 2 months ago #116190 by Ilya
Replied by Ilya on topic More than 9 axes with servo
I was trying to connect the motion.analog-out-00 and x-pid.comand pins, But it certainly doesn't work
I can't control the drive by position using halcmd, only by speed

I don't know what happens behind the scenes when I, for example, use the command "G0 X1000". Maybe it would help me

Here is part of my working configuration (If you want, I can upload the full file):
Code:
# position controler setp x-pid.Pgain [JOINT_0]P setp x-pid.Igain [JOINT_0]I setp x-pid.Dgain [JOINT_0]D setp x-pid.FF0 [JOINT_0]FF0 setp x-pid.FF1 [JOINT_0]FF1 setp x-pid.FF2 [JOINT_0]FF2 setp x-pid.deadband [JOINT_0]DEADBAND setp x-pid.maxoutput [JOINT_0]MAX_OUTPUT net x-enable => x-pid.enable net x-pos-cmd => x-pid.command net x-pos-fb => x-pid.feedback net x-vel-cmd <= x-pid.output # axis interface net x-home-sw-in => joint.0.home-sw-in net x-enable <= joint.0.amp-enable-out net x-amp-fault => joint.0.amp-fault-in net x-pos-cmd <= joint.0.motor-pos-cmd net x-pos-fb => joint.0.motor-pos-fb net x-pos-joint <= joint.0.pos-fb net x-homed <= joint.0.homed net x-homing <= joint.0.homing net x-neg-lim-in => joint.0.neg-lim-sw-in net x-pos-lim-in => joint.0.pos-lim-sw-in # * lcec - component for working with Ethercat # voltage is statically enabled as soon as LCNC is running setp lcec.0.3A1.srv-enable-volt 1 # set motor position scale (default 1 motor revolution) setp lcec.0.3A1.pos-scale [JOINT_0]SCALE setp lcec.0.3A1.extenc-scale [JOINT_0]ENC_SCALE # switch on if joint is enables # this signal is used for the fault autoreset feature, too net x-enable => lcec.0.3A1.srv-switch-on # enable operation if joint is enabled # The delta driver internally delay this signal # till switched-on feedback is set to 1 net x-enable => lcec.0.3A1.srv-enable # check driver fault status net x-amp-fault <= lcec.0.3A1.srv-fault # output velocity command from position control # the scale of this value respects the setting # of srv-pos-scale. if scale is set to 1.0 this # means 1 motor revolution per second. net x-vel-cmd => lcec.0.3A1.srv-vel-cmd # motor encoder position is used as joint # position feedback net x-pos-fb <= lcec.0.3A1.enc-pos #net x-index x-pid.index-enable lcec.0.3A1.enc-index-ena

thanks,
ilya
Last edit: 8 years 2 months ago by Ilya.

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8 years 2 months ago - 8 years 2 months ago #116218 by Todd Zuercher
Replied by Todd Zuercher on topic More than 9 axes with servo
To send a position command to that servo, you will have to disconnect it from the joint.0.motor-pos-cmd. and to prevent following errors you would also need to do something to fool the joint.0.motor-pos-fb.

For your test it might be simpler to set up a new pid loop that isn't already connected to a joint/axis. There is a lot of little things that would need to be faked, fooled or manipulated in some way to separate it from the old system.

All you should need is a pid loop that you send a position command to. Connect the output of the PID to the velocity command input of your servo, And connect the encoder feedback to the PID's feedback input. Oh, and some way to enable/disable the drive.
Last edit: 8 years 2 months ago by Todd Zuercher.
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8 years 2 months ago #116375 by andypugh
Replied by andypugh on topic More than 9 axes with servo

Todd Zuercher wrote: All you should need is a pid loop that you send a position command to. Connect the output of the PID to the velocity command input of your servo, And connect the encoder feedback to the PID's feedback input. Oh, and some way to enable/disable the drive.


Once this is working it might be useful to interpose a Limit3 component between the motion.analog-out and the pid.command
This could then have its velocity limit pin connected to a second motion.analog-out in order to control both the speed and final position of the movement.
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8 years 2 months ago #116474 by Ilya
Replied by Ilya on topic More than 9 axes with servo
Thanks to Todd and Andy for your advices! They were very useful. Limit3 component is just great!
For the test, i had to connect joint.0.amp-enable-out to two servos and two PIDs. If I don't come up with something smarter, I'll have to do it for four servos at once..
Here's what works now:
Code:
setp n1-pid.Pgain [JOINT_3]P setp n1-pid.Igain [JOINT_3]I setp n1-pid.Dgain [JOINT_3]D setp n1-pid.FF0 [JOINT_3]FF0 setp n1-pid.FF1 [JOINT_3]FF1 setp n1-pid.FF2 [JOINT_3]FF2 setp n1-pid.deadband [JOINT_3]DEADBAND setp n1-pid.maxoutput [JOINT_3]MAX_OUTPUT net x-enable => n1-pid.enable net n1-m68-to-limit3 motion.analog-out-00 => limit3.0.in setp limit3.0.min -1000 setp limit3.0.max 1000 setp limit3.0.maxa 200 setp limit3.0.maxv 100 setp limit3.0.smooth-steps 10 net n1-limit3-to-pid limit3.0.out => n1-pid.command net n1-pos-fb => n1-pid.feedback net n1-vel-cmd <= n1-pid.output setp lcec.0.3A4.srv-enable-volt 1 setp lcec.0.3A4.pos-scale [JOINT_3]SCALE setp lcec.0.3A4.extenc-scale [JOINT_3]ENC_SCALE net x-enable => lcec.0.3A4.srv-switch-on net x-enable => lcec.0.3A4.srv-enable net n1-amp-fault <= lcec.0.3A4.srv-fault net n1-vel-cmd => lcec.0.3A4.srv-vel-cmd net n1-pos-fb <= lcec.0.3A4.enc-pos net n1-brake <= lcec.0.3A4.srv-oper-enabled

Now i have to figure out how to do the homing for that axis

thanks,
Ilya

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