Dc servo motor control

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05 Apr 2022 15:12 #239342 by Joeymcc
Replied by Joeymcc on topic Dc servo motor control
I changed it to x enable to get going.

My motors keep moving by themselves, both x and y axis, x is on the gantry and is a single motor, encoder and motor direction is correct, I have tried adding "-" values in the ini file to try different motor and encoder direction but no help. They move even when analogue signal wires are completely removed. This happens in the pncconfig, in linuxcnc it errors as soon as i to turn on with joint follow errors 
 

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05 Apr 2022 15:19 #239344 by tommylight
Replied by tommylight on topic Dc servo motor control


My motors keep moving by themselves, both x and y axis, x is on the gantry and is a single motor, encoder and motor direction is correct, I have tried adding "-" values in the ini file to try different motor and encoder direction but no help. They move even when analogue signal wires are completely removed. This happens in the pncconfig, in linuxcnc it errors as soon as i to turn on with joint follow errors 

 

That is normal in velocity servo drives.
Make sure that when LinuxCNC errors out with joint following error, the enable goes off and the drives stop moving.
If the motors are moving before pressing "enable" in LinuxCNC, do not proceed to try tuning, that usually ends up in tears.
Enable HAS to be be controlled by LinuxCNC, that is not negotiable on velocity servo systems. :)

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05 Apr 2022 15:45 #239348 by Joeymcc
Replied by Joeymcc on topic Dc servo motor control
Yes, with x enable it is working ok,

It errors out as soon as i click power button,  so i cannot tune/test in the calibration window

The values entered into the calibration to start are the same as in the tutorial but it errors straight away. I tried also adding the "-" but no help.

It is always errors on joint 1 or joint 2 which is the y and y tandem

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05 Apr 2022 16:22 #239357 by Joeymcc
Replied by Joeymcc on topic Dc servo motor control
Ah I am getting somewhere now! I had an error and i was lookong at the wrong joint!

At 50 my machine had lots of vibration, i had to go very low to stop it. For some reason my y axis jog o cannot use, it is greyed out

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05 Apr 2022 16:33 #239359 by Joeymcc
Replied by Joeymcc on topic Dc servo motor control
Ah, i changed homing to 0 in my ini file, working now, will change back after tuning. 
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05 Apr 2022 20:40 #239384 by tommylight
Replied by tommylight on topic Dc servo motor control
Nice, now you should refer to the tutorial about servo tuning, go step by step, no skipping. Do that for a single axis only, only after having one axis working continue to the next as trying to do everything at once will very quickly become frustrating and yield no results. This can be done after being able to enable the machine and no errors until you try to jog and no motors are moving on their own.
You can use an android phone or tablet with any software that uses the built in sensors by looking at the accelerometer while the phone is standing on or near the motor. That way you can see from far away how much the machine is vibrating while setting the P gain. I think i have pictures of it on that tutorial.
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05 Apr 2022 20:49 #239387 by Joeymcc
Replied by Joeymcc on topic Dc servo motor control
Thanks Tommy, im still having some problems with the y axis (2 motors)

I set up the 2 home switches. I have y and y2 tandem motor, encoder and switches. Directions and encoders are good. I can start linuxcnc and home the y axis, it homes perfectly, squares the gantry and in the DRO is the home offset I set in pncconfig, but the Y axis jog keys are greyed out and cannot be used. Not really sure what can cause that.
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05 Apr 2022 20:57 #239388 by rodw
Replied by rodw on topic Dc servo motor control
You might need to press home all
If you have not got your other axes set up for homing yet, yo can set them to immediate homing as discussed in the homing configuration page in the main docs.

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05 Apr 2022 21:03 #239389 by tommylight
Replied by tommylight on topic Dc servo motor control
Tandem axis/joints/motors must have -1 in home_sequence, otherwise it will not jog. Even when set correctly, it will not jog before homing the machine.
So since the Y axis is moving and homing, set it to -1 and give it a try.
Just for kicks, set to to home slowly and set the offset of one side 2mm more, never gets old looking at that ! :)
Yeah also very useful to make sure the sensor for y2 is actually y2!

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05 Apr 2022 22:00 #239393 by Joeymcc
Replied by Joeymcc on topic Dc servo motor control
Thanks tommy il get a play with the homing/squaring after some issues are fixed, Ive got going now, however i have a very noisy servo/drive on the rhs of the gantry, it was noisy before this retrofit started, the other side done similar before and i found a few bad solder joints, this one looks ok. Not sure what the cause os, brushes look good too. Had you seen any noisy ones before tommy? This has been a bit of an issue this past year, noisy and a small vibration

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