stepgen.03.maxvel is too big for current step timings & position-scale, Clipping

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19 Nov 2023 15:19 #285906 by Muecke
Hallo zusammen,

ich verstehe die Meldung nicht ganz, :-( welche Werte sind im Verhältnis zueinander nicht OK und in welchem Verhältnis muss was zueinander stehen, damit es passt?

stepgen.03.maxvel is too big for current step timings & position-scale, Clipping to Max possible


Mesa: 7i95
Joint 3 = Achse Y
Mikroschritte: 1/2 (1zu1 kann mein Treiber nicht)
Motor: 1.8°
Getriebe: 40 zu 1 (Eingangsumdrehungen 40, Ausgangsumdrehungen 1)

Leider ist die Ausgangsgeschwindigkeit zu niedrig, ich würde eine viel höhere Geschwindigkeit benötigen. Allerdings meckert LinuxCNC bei der Anzeige der Maximaldrehzahl (und Warnungen mag ich nicht).

Daher meine Frage, wie bzw. worauf muss ich bei der Konfiguration von Y (Joint 3) achten?

Im Anhang meine aktuelle INI und HAL.

Gruß Mücke

INI
 

File Attachment:

File Name: nov_23_ini.txt
File Size:5 KB

HAL
 

File Attachment:

File Name: main_hal.txt
File Size:7 KB

 

File Attachment:

File Name: io_hal.hal
File Size:1 KB

 
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19 Nov 2023 15:58 #285912 by PCW
The warning means that you cannot reach the specified joint
maximum velocity with your current step timings, that, you have

STEPLEN = 2500
STEPSPACE = 2500

This means the total step rate can not be greater the 200 KHz
( 1/(StepSpace+StepLen), but your maximum velocity (7200 mm/s !)
times the scaling (44.444)  requires a 320 KHz

Did you really mean 7.2 meters per second maximum Y Velocity?

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19 Nov 2023 16:20 #285914 by Muecke
7.2 m/s is clearly too high.
The exit velocity is very low.
File Attachment:

You are right, I could make the scale smaller, then the output speed should be higher.

I can't understand your calculation
1/(step size + step size) * scaling = KHz
1/(2500+2500)*44.444 = I arrive at 0.008888 ?
How do you arrive at 320 KHz?

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19 Nov 2023 16:38 #285915 by PCW
7200 (mm/s) * 44.444 steps/mm = 320K steps/s

1/(2500e-9+2500e-9) = 200K maximum step rate (2500 is in nanoseconds)

You don't need to change the scale, just reduce the Y/Joint3 max velocity
so something reasonable (HAL axis units are in seconds, not minutes,
did you mean 7.2 Meters per minute? that is 120 mm/s)
The following user(s) said Thank You: Muecke

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19 Nov 2023 16:49 #285916 by Muecke
I will print out your calculation example and hang it on my info wall, THANK YOU!

I started with 3600mm/s, and the part turns so slowly, so I just increased the number, the only reason was to make it bigger.

The axle should rotate faster.

Not expedient. I could install a smaller dribble (now 40/1).

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19 Nov 2023 17:19 #285919 by tommylight
mikroschritte 1/2 =400 steps per revolution
reduction 40/1 = 16000 steps per revolution
Your scaling is not OK.
What does the reduction drive?

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19 Nov 2023 17:25 #285920 by PCW
Yes, that reduction drive does not look appropriate for a linear axis

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19 Nov 2023 17:36 #285924 by Muecke

What does the reduction drive?

I need more strength.
This axle turns a car wheel, it doesn't have to run fast but it would be nice to run a little faster than now.

Picture, the motor with dribble is on the back, I don't have another picture right now.

Calculation:
Corner of travel: 360 mm / revolution
microsteps 1/2 =400 steps per revolution
reduction 40/1 = 16000 steps per revolution

360 mm = 16,000 Steps
1 mm = (1*16,000) / 360 mm
1 mm = 44,4444444 Steps / mm

Why is the calculation wrong?

yes LinuxCNC would like to have a linear axis for the Y axis, but this is round ;-)


 
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19 Nov 2023 17:42 #285925 by tommylight

Corner of travel: 360 mm / revolution

Of what?
Nothing in that picture has a perimeter of 360mm.
what diameter shaft?
what wheel size?
what tire size?
Do you want to scale it to shaft or to wheel?

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19 Nov 2023 18:08 #285930 by Muecke
I used 360mm because that is the number of degrees of a circle ;-)
The shaft A has a diameter of 5cm (I think, I have to measure it).
The tyre can have a diameter of 40cm to approx. 110cm.

If you ask like that, I would do the dimensioning based on the shaft.
I have tested by hand a speed of about 7mm/second when I want to rotate the tyre under load.

It would be good if I could move the shaft at 7mm/second under load, more than that in rapid traverse.
At the moment I doubt that I can achieve these speeds with this gearbox.

 
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