8i20

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4 years 7 months ago #236145 by PCW
Replied by PCW on topic 8i20
Does the init cycle run without fault?

What I am getting at is that you may get faults due to instability,
either in LinuxCNCs PID = LinuxCNC PID tuning issues or in the 8I20.
If you cannot set a static current in the 8i20 without fault, its likely the
8I20s current loop PI gains are too high for your motor.

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4 years 7 months ago #236146 by andypugh
Replied by andypugh on topic 8i20

setp [HMOT](CARD0).0.8i20.0.0.current-maxlim 0.020
setp [HMOT](CARD0).0.8i20.0.0.current-minlim -0.020

Is this just for testing? I have forgotten how the calculations work, but this seems odd. 

I run both my machines with 8i20, but as they have resolvers the configs won't transfer straight across. 
Code:
net x-meas-angle bldc.0.rotor-angle => hm2_5i23.0.8i20.0.2.angle setp hm2_5i23.0.8i20.0.2.current-maxlim 7.5 setp hm2_5i23.0.8i20.0.2.current-minlim -7.5 net x-cmd joint.0.motor-pos-cmd => pid.0.command net x-vel-cmd joint.0.vel-cmd => pid.0.command-deriv net x-fb hm2_5i23.0.resolver.01.position pid.0.feedback joint.0.motor-pos-fb net x-vel-fb hm2_5i23.0.resolver.01.velocity pid.0.feedback-deriv setp hm2_5i23.0.resolver.01.velocity-scale -1 net x-pid pid.0.output => hm2_5i23.0.8i20.0.2.current #12 motor 49 pulley 5 leadscrew pitch setp hm2_5i23.0.resolver.01.scale -1.2244898 net amp-enable-and-DC-good pid.0.enable setp pid.0.Pgain [JOINT_0]PGAIN setp pid.0.Igain [JOINT_0]IGAIN setp pid.0.Dgain [JOINT_0]DGAIN setp pid.0.bias [JOINT_0]BIAS setp pid.0.FF0 [JOINT_0]FF0 setp pid.0.FF1 [JOINT_0]FF1 setp pid.0.FF2 [JOINT_0]FF2 setp pid.0.deadband [JOINT_0]DEADBAND setp pid.0.maxoutput [JOINT_0]MAXOUTPUT setp bldc.0.scale -16777216 setp bldc.0.poles 6 setp bldc.0.lead-angle 0 setp bldc.0.encoder-offset -950000

Try with the max and min current matching the nvmaxcurrent (7.5A = 0x2EE, which you seem to have)

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4 years 7 months ago #236166 by dkraft
Replied by dkraft on topic 8i20
Its the init that trips it. struggling with a way to diagnose it.

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4 years 7 months ago #236172 by andypugh
Replied by andypugh on topic 8i20
Does it always trigger? Or is it OK the second time? I am wondering about transient effects as the rotor snaps in to phase.

I guess you have tried both higher and lower initvalue values?

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4 years 7 months ago #236173 by dkraft
Replied by dkraft on topic 8i20
How do you drive the input enable and read the fault out physical pins on the 8i20? Do you setup pins from the driver board?

Currently testing, I'm driving input enable from 5v off the serial connector.. not sure if that is trouble.

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4 years 7 months ago #236201 by dkraft
Replied by dkraft on topic 8i20
Figured out the tripping error. Too low impedance on the motor detects as a short apparently.
250Kv motors will never work no matter how low you try to drive it ;)

Thanks!

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4 years 7 months ago #236202 by andypugh
Replied by andypugh on topic 8i20
Are these RC aircraft motors?

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4 years 7 months ago #236205 by PCW
Replied by PCW on topic 8i20
Yes I forgot to ask this, what type of motor and perhaps more important, what is the motor inductance?

The 8I20 is intended for medium/high inductance motors (standard AC 230V servo motors)

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4 years 7 months ago #236225 by dkraft
Replied by dkraft on topic 8i20
yes. I thought I'd be clever and debug with a low inductance motor, didn't work. got it working with a washing machine motor though..

Moving on to the yaskawa servo motors now.

Your help with the commutation signals was crucial. Thank You.

Last piece was bldc.init ;)

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4 years 7 months ago #237321 by dkraft
Replied by dkraft on topic 8i20
How can I get my encoder offset ?
I'm thinking it's aligned with the "U+, VW-" method, then average the 6 positions found modulus encoder scale / poles...

(I hacked a CMT102 on a servo with 6 poles)

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