Brother TC-225 / TC-229 adventure!

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29 Nov 2017 14:59 #102483 by ihavenofish
g64 p0.001" q0 is standard for me. this behaves smooth.
circles also tend to be smooth, but have a bit too much error for my tastes (to be fair, you don't generally make a finish pass at 200+ipm and the error is only .001" - ive seen worse in better machines.

the error is actually not my complaint. if it tracked at 0.0005" at speed under 50ipm and .001" at speeds up to 200ipm and strayed a bit at 787 which is primarily only rapids, it would be perfectly fine. its the clunk at the beginning of each move which in the case of the z becomes instability that makes the think not usable yet. x is borderline, y is a bit bad, z I don't even like jogging in tests its so bad.

we also have the trajectory planner misbehaving as mentioned before, though that's got nothing to do with the straight line tuning.

I have the files up there, please look to see if anything is clearly not right.

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29 Nov 2017 15:10 - 29 Nov 2017 15:11 #102484 by ihavenofish

laserK wrote: Which brings me to the next problem: I don't have a manual for the Toshiba RA Drive.
There are 6 potentiometers on the front. I, SZ, P, SPD and WZ, UZ
I and P are clear,
SPD = speed?
SZ = ?
WZ = ?
UZ = ?

spd don't touch, that's the v/rpm reference.
sz/wz/uz, no idea, theres nothing on my drives that have a similar label. on mine you have 2 gain pots, which represent p and I though not labeled p and I - they have a diagram showing what they do.


@ihavenofish
Do you know the stock values of the acceleration? Were does this information of jerk limit in the brother control come from? Could the jerk control be an analog low pass filter?.


youd need to run the stock control to read them. I suspect yours is slower than mine a little. mine is 150ms. what that means is 150ms from 0 to 787ipm (591 on z). that works out to roughly 0.225g on the x and y or 87in/in2 as many people are used to. ive tried every acceleration from 10in/in2 to 200in/in2 (0.5g) and there is ALWAYS the same clunk. less pronounced when its slow, but not much.

as super low speeds (say, 2ipm) you don't notice the clunk, because the acceleration to that speed is basically instant. it comes into play mostly above 10ipm or so.
Last edit: 29 Nov 2017 15:11 by ihavenofish.

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29 Nov 2017 18:38 #102499 by laserK
Thanks! I'll try P and I then. My guess is, that SZ, WZ, and UZ are limits for Speed, Power/Current, and Voltage?
I'll also check the velocity ramps of the original control to get a feeling for the max acceleration.

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29 Nov 2017 18:48 #102500 by ihavenofish
i just thought of something. alot of amps have jerk control built into them as a filter - usually modern step controlled ones.

but... if this drive has a filter, would it cause linuxcnc to attempt to compensate during acceleration and deceleration and basically have the 2 fighting?

that's just a random thought here.

the only other thing that might be different on the brother control i that it may be quite lazy on following as its primary use is point to point. so maybe it has a broad allowance when doing curves. hmm.

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03 Dec 2017 22:28 #102632 by laserK
I did some tuning on the servo amps. The value for P was at the lowest possible setting. Increasing it was a huge step forward. I am not done with the tuning, but so far I could reduce the maximum ferror to ~0.03mm @ 0.1G and 10m/min. I will try larger values of P and I on the servo amp soon. Right now I need a lot of FF1.

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03 Dec 2017 23:45 #102639 by PCW
For FF1 its not so much "a lot" but rather the right amount.
(If you scale the analog out in machine units per second instead of volts, FF1 should be 1.000)

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04 Dec 2017 00:29 #102640 by laserK
right now ff1 is around 3 with dimensionless scaling as you suggested. That seems too much..

~4000rpm @10V, 5mm ballscrew => 33mm/(sV)

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04 Dec 2017 01:43 #102644 by PCW
is ff1 3 with maxscale =333? (333 should be mm/S fullscale with you numbers)

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04 Dec 2017 04:03 #102645 by ihavenofish
if I don't play with D, I usually end up near 0.7ish for FF1

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04 Dec 2017 21:58 #102681 by laserK

PCW wrote: is ff1 3 with maxscale =333? (333 should be mm/S fullscale with you numbers)

I had around 0.1 with maxscale = 10. that should translate into ~3.3 with maxscale 333, right?

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