getting started with 8i20

clematites93 wrote:

reference angle --> is supplied by the encoder
current --> is supplied by bldc.0.value

Yes, but no

The angle is provided by the bldc component, based on the encoder feedback. Or, in fact, on whatever other feedback it is using. The bldc component can also use Hall signals or the 4-channel feedback from the Fanuc encoders.

The current command can often be supplied directly from the position control PID component. Unless you are homing magnetically or to index, in which case the bldc component needs to be able to over-ride the PID output to run the homing sequence.

The main purpose of the bldc component is to perform the commutation calculations. It calculates what phase angle the current needs to be applied at, and provides a range of command types to achieve that for various types of motor drive.

(And, if your motor has Hall sensors, I really strongly advise using them, because the magnetic homing mode is unreliable under load and index homing moves the machine in unpredictable ways)

* It is probably necessary to use, when Axis works, halcmd -kf with another window. Is it correct ?

Yes. Unless you use the "view hal configuration" menu option, but that is much less convenient.

* What value to give to the setup value current ?

That's up to you. Not so much that the motor melts into the carpet. DAMHIK.

* What is the final aim of this manipulation --> increase the speed of the motor; Why ?

To see how fast the motor _can_ run, independent of the position control loop. And to see if it runs equally well in both directions. If it doesn't run equally well in both directions then the homing sequence probably isn't working right.

Again, if you have Hall sensors, use them. If not, use index homing. But index homing needs you to work out where the index is relative to the motor phase angle _for_each_motor_.

clematites93 wrote:

Is it a good idea to limit the current in the motor whatever happens during the test session.?
(whitout affecting NVMAXCURRENT)

To an extent, though you won't get a real feel for the motor capability if you set it too low.

I would set the limit to the motor nameplate rated current, otherwise the motor will appear very slow and weak.

When fitted to the machine you would probably set the limit to the motor max current, just for the extra accelleration. (I think my motors are rated 3A continuous, 7.5A max)

0.6A is actually very low for the 8i20. What is your max motor current?

I have only melted the carpet once, and that was when I was testing the system and forgot that the motor was stalled on the wrong commutation settings, and running high current. When the commutation is right the motor would have been spinning and it would have been hard to forget that it was powered up.

clematites93 wrote:

# Estop loopback + bldc + pid
[code]   net   after-estop-touch iocontrol.0.user-enable-out  =>   bldc.0.init   # after click on touch F1, start of bldc
net   after-estop-touch  => pid.x.enable

The engine positions slowly, by jerks, apparently always in the same place.

I think that you want to connect pid.x.enable to the init-done pin, so that the pid does not interfere with the bldc.homing motion.

Do you _know_ that the index is at the motor electrical zero position?

You can find this sort-off of-line.
First find a small power supply, even a battery, and connect the +ve to phase A of the motor, and the negative to phases B and C.
That will find you one of the magnetic zeros. You probably have two of them. If the current is low then you can probably snap the motor shaft between them by hand.

Mark these positions with a marker pen on the shaft and face of the motor (or mark the keyway position if there is one) And count them. That is half your number of motor poles.

Now, start LinuxCNC but keep e-stop active. Open a halmeter window looking at encoder counts. You should see the number change as you manually rotate the shaft.

Now, to find the index you need to set index enable true, then rotate the shaft by hand until the counts go to zero.It doesn't matter if you over-shoot, you can turn back to exactly zero. Now, does that position align with one of the marks you made earlier?