Stall detection with 2 motors

noisettetbou

I've built a new printer and I've got a problem with stall detection in Y. It's OK in X and my other printer.
I've got 2 motors in series in opposate direction. Is it the problem ?
Either the motors are forcing or the detection is false. No middle.

noisettetbou

It's on a Duet2wifi with RRF 3.1.1.

Phaedrux

Post your config.g and homing files.

Trying to stall multiple motors at the same time is problematic.

For reference: https://duet3d.dozuki.com/Wiki/Stall_detection_and_sensorless_homing

noisettetbou

@Phaedrux
Config.g :
; Drives
M569 P0 S1 ; physical drive 0 goes forwards
M569 P1 S1 ; physical drive 1 goes forwards
M569 P2 S1 ; physical drive 2 goes forwards
M569 P3 S1 ; physical drive 3 goes forwards
M569 P4 S1 ; physical drive 4 goes forwards
M584 X0 Y1 Z2 E3:4 ; set drive mapping
M350 X16 Y16 Z16 E16:16 I1 ; configure microstepping with interpolation
M92 X53.33 Y106.67 Z106.67 E415.00:415.00 ; set steps per mm
M566 X900 Y900 Z300 E120:120 ; set maximum instantaneous speed changes (mm/min)
M203 X18000 Y18000 Z6000 E1200:1200 ; set maximum speeds (mm/min)
M201 X500 Y500 Z300 E250:250 ; set accelerations (mm/s^2)
M906 X2000 Y2100 Z1800 E700:700 I30 ; set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Axis Limits
M208 X-210 Y-210 Z0 S1 ; set axis minima
M208 X210 Y210 Z510 S0 ; set axis maxima

; Endstops
M574 X1 S3 ; configure sensorless endstop for low end on X
M574 Y1 S3 ; configure sensorless endstop for low end on Y
; M574 Z1 S2 ; configure Z-probe endstop for low end on Z
M574 Z2 S3 ; configure Z-probe endstop for high end on Z
M915 X S0 F0 R0 ; configure stall detection X
M915 Y S0 F0 R0 ; configure stall detection Y
M915 Z S0 F0 R0 ; configure stall detection Z

HomeY.g
M913 Y50 ; reduce current
M400
G1 H1 Y-450 F12000 ; move X axis endstop
M913 Y100 ; increase current
G90 ; absolute positioning

noisettetbou

@Phaedrux
I understand trying to stall multiple motors at the same time is problematic but it's work on my other printer (nema23) and on my X axis on this one.
The only differences on this printer (nema17) with the 2 motors of X are the 2 motors of Y turn in opposate direction and are slightly stronger.

Phaedrux

You're missing an H value from your M915. Did you calculate it?

https://duet3d.dozuki.com/Wiki/Stall_detection_and_sensorless_homing#Section_Minimum_recommended_speed_for_stall_detection

@noisettetbou said in Stall detection with 2 motors:

M574 X1 S3 ; configure sensorless endstop for low end on X
M574 Y1 S3 ; configure sensorless endstop for low end on Y

You say you're using 3.1.1 but your config is using syntax for RRF2.

Please send M115 and confirm what firmware you're actually using.

noisettetbou

@Phaedrux
09/09/2020 à 21:53:09 M115
FIRMWARE_NAME: RepRapFirmware for Duet 2 WiFi/Ethernet FIRMWARE_VERSION: 3.1.1 ELECTRONICS: Duet WiFi 1.02 or later FIRMWARE_DATE: 2020-05-19b2

noisettetbou

@Phaedrux
And I've tryed M574 Y1 S4 and indicate some differents M915 H parameters but no change. Force on endstop or false detection.

Phaedrux

Well what behaviour do you want when a stall is detected? stop both motors or stop each individually?

https://duet3d.dozuki.com/Wiki/Gcode#Section_M574_RepRapFirmware_Num_3

New endstop type S4 means use motor stall detection (like S3) but if there are multiple motors, stop each one individually as it stalls. S3 means use motor stall detection but as in RRF 2: stop all relevant motors when the first one stalls.

What did you calculate for the H value?

Can you send M98 P"config.g" in the gcode console and report the results?

noisettetbou

@Phaedrux
And I'm not sure of my calculation of the H parameter and speed. This is my Y motors (2 in series) of my Y axis specifications :
Spécification électrique
Numéro de pièce du fabricant: 17HS24-2104D
Type de moteur: Bipolar Stepper
Angle de pas: 1.8 deg
Couple de maintien: 65Ncm(92.3oz.in)
Courant/phase: 2.10A
Tension: 3.360V
Résistance/phase: 1.60ohms
Inductance: 3.00mH ± 20%(1KHz)

I've found more than 1000 mm/s. It's crazy !

noisettetbou

@Phaedrux said in Stall detection with 2 motors:

Well what behaviour do you want when a stall is detected? stop both motors or stop each individually?

I want to stop both motors. No choice, they're in series on the same driver.
This is the results of my M98 P"config.g" :
09/09/2020 à 22:16:49 M98 P"config.g"
HTTP is enabled on port 80
FTP is disabled
TELNET is disabled
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 365C
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 269C

Note my My PID aren't done for heaters errors.

Phaedrux

@noisettetbou said in Stall detection with 2 motors:

I've found more than 1000 mm/s. It's crazy !

That seems wrong based on your motor specs. My calculation gives 145mm/s

Stall detection H value			
Hmin = full_steps_per_rev * rated_current * actual_current/(sqrt(2) * pi * rated_holding_torque)			
Full_steps_per_rev	200		
Rated_current (A)	2.100		
Actual_Current (A)	1.000		
Rated_holding_torque (Nm)	0.650		
Squareroot(2)	1.414		
Pi	3.142		
Hmin	145.436

You may be able to reduce that speed further if you reduce the motor current further. You should try reducing it as much as possible such that you still have reliable movement. Right now you're using 50%, try 30%.

noisettetbou

@Phaedrux
Thanks for the calculation. I've confused the units of torque.

I've tried speeds up to 300 mm/s and differents current between 20 and 100% but nothing.

Phaedrux

When you say the motors rotate in opposite directions, what do you mean?

Can you post a photo of the printer?

noisettetbou

@Phaedrux
That's a link to a photo of Y axis :
https://photos.app.goo.gl/oeFLBnE1iaKtcJMNA
The motors are biaxials and synchonysed by a shaft

oliof

@noisettetbou possibly crazy talk but could you disable one stepper for homing only? As they're synchronized by a shaft you should be able to live with that.

noisettetbou

@oliof
It's a good idea. I've tried and it is the same problem.
So 2 motors on same driver and the series wiring aren't the source of the problem.
I'm trying to invert drivers.

noisettetbou

I've tried to invert driver with X and always the problem. As if my Y motors aren't compatibles with the stall detection.
Is it possible ? Crazy, no ?

oliof

Oh two steppers on a single driver? I can see how that will be bothersome/impossible. Maybe if you drive each motor independently ...

noisettetbou

@oliof
It's no a problem if current is respected. I use two motors on same driver in X axis and no problem. And I done as you said for trying, so there is only one motor right now, and no good stall detection...