Trouble configuring LAOS

Hi,
after quite a long break I am finally getting back to setting up LAOS for our Lasercutter. I was away, in hospital, busy with other projects, etc...

Its a mostly Lasersaur-based DIY machine, currently using EMC2, hoping to finally switch to LAOS very soon. It uses external "proper" stepper drivers, no Polulus or the like.
The LAOS Board is completed and appears to work fine. I am currently running laoslaser-29-12-2012.bin on a rev.4 board with I2C display board connected.

I am really having trouble figuring out the configuration. Stuff just isn't quite working the way I expect it. So let me just list some config values and the current behaviour.

laser.enable 0                  ; Laser enable signal polarity [0/1]

Currently bypassed in hardware for testing.

laser.on 0                      ; Laser on signal polarity [0/1]
laser.pwm.min  90               ; minimum pwm value [%]
laser.pwm.max  0                ; maximum pwm value [%]
laser.pwm.freq 1000             ; pwm frequency [Hz]

The Laser PWM output appears to be always high, according to my scope. Even when no job is running. The Laser On output works correctly.

motion.homespeed  500            ; Homing speed [mm/sec]

Is this really mm/sec based on the x/y scale values? I read somewhere that it was microseconds per step, is that outdated information? It would explain the behaviour I had yesterday, using firmware built from Git. There it appeared that the higher the value is, the slower it was moving.

motion.speed  100                ; max linear speed [mm/sec]
motion.accel  500               ; linear acceleration [mm/sec2]

Been playing with these values a lot and just can't get it to work properly. When I use the move function in the menu, it accelerates slowly and continues for quite a bit after letting go of the joystick.

x.scale 52493
y.scale -52493

I calculated that we should have 52493 steps per meter. Though not entirely sure if my calculation is correct. :)

x.home 10                   ; home positions [um] 
x.min 0                         ; minimal position [um]
x.max 300000                    ; maximum position [um]
x.rest 300000                   ; rest position [um]

Values are not setup properly yet. I am not entirely sure what the difference between min/max position, home position and rest position is. Can someone explain? If scale is negative as in our y, do these positions have to be negative too?
I want the home position to be at the upper left corner. With the current configuration the movements of the joystick with the move option correspond to the movements of the head.
We have limit switches on both sides on both axes. Those are wired to a homemade "safety" board that will disable the laser and the stepper drivers if a switch is pressed or the lid is opened, unless an override line is pulled up which our modified EMC2 build does while homing (otherwise it could never move away from the switches). For the current LAOS test run, the override is permamently active.

x.speed 100                    ; maximum speed [mm/sec]

I guess this is the maximum speed within a job? So the motion.speed value is only for manual movement?

Would anyone be willing to help me with the setup in realtime, lets say through IRC or Skype? Its somewhat frustrating to have to write in a forum with a problem when I am at the Fablab, and wait possibly several days for an answer, being unable to continue. Especially when its stuff someone that knows the system by heart could probably answer in 5 seconds. :)

Replies (3)

RE: Trouble configuring LAOS - Added by hugomeiland almost 12 years ago

Hi Topy,

loads of questions, let me go by them one by one....

1.
laser.on 0 ; Laser on signal polarity [0/1]
laser.pwm.min 90 ; minimum pwm value [%]
laser.pwm.max 0 ; maximum pwm value [%]
laser.pwm.freq 1000 ; pwm frequency [Hz]

The Laser PWM output appears to be always high, according to my scope. Even when no job is running. The Laser On output works correctly.

you may turn the value for min/max around; the current values are for inverted input of the laser power.

2.
motion.homespeed 500 ; Homing speed [mm/sec]

not sure on this one...

3.
motion.speed 100 ; max linear speed [mm/sec]
motion.accel 500 ; linear acceleration [mm/sec2]

I do not trut the joystick on this one; function depends on i2c bus, and during movements this bus is not read enough (see your cancel button bug)... these are the same values I'm using with a light 20/30 cm machine. what size is your machine (and a pic of the mechanics?) the accel should not be too high if you have heavy mechanis inside..

4.
I calculated that we should have 52493 steps per meter. Though not entirely sure if my calculation is correct. :)
x.home 10 ; home positions [um]
x.min 0 ; minimal position [um]
x.max 300000 ; maximum position [um]
x.rest 300000 ; rest position [um]

Values are not setup properly yet. I am not entirely sure what the difference between min/max position, home position and rest position is. Can someone explain?

let me try, this is my settings for it:

; Next values are valid for axis x,y,z and e
x.pol 1 ; home/limit sensor polarity [1/0]
x.scale 158516 ; axis scaling [steps/meter]
;x.scale 79258
; use negative number to invert direction [1/0]
x.homedir 1 ; state of the direction signal when homing
x.home 400000 ; home positions [um]
x.min 0 ; minimal position [um]
x.max 300000 ; maximum position [um]
x.rest 300000 ; rest position [um]
x.speed 800 ; maximum speed [mm/sec]
x.invert 0 ; Invert signal polarity for step signal [1/0]
when I'm standing in front of the machine:
- min: is lower left corner
- homing switches are located at top right corner
- laser bed is starting at min, and sized 300 mm to the right and 200mm to the top
- when the job is finished, i want the laser to go to rest: lower right corner
a picture will probably help; I'll try that in a couple of days...

5.
x.speed 100 ; maximum speed [mm/sec]

I guess this is the maximum speed within a job? So the motion.speed value is only for manual movement?

not sure on this one too; motion values are the one's i've been setting up to get my laser running correctly, as you can see above, my current setting is quite high...

6.
Would anyone be willing to help me with the setup in realtime, lets say through IRC or Skype?

sure, let me know when you are at the lab; if it fits we can alway open up skype...

have fun!

Hugo

RE: Trouble configuring LAOS - Added by peteruithoven almost 12 years ago

Hi Topy44, a humble suggestion; maybe you could help clarify the configuration file wiki while your learning this.
http://redmine.laoslaser.org/projects/laos/wiki/LAOS_configuration_file

RE: Trouble configuring LAOS - Added by Topy44 almost 12 years ago

It works!
Thanks to the help by Hugo and another few hours of experimenting, I finally got it (almost) all working. I just successfully engraved and cut a piece of wood as a test. There are still some issues, including our safetyboard being bypassed at the moment, and I still need to experiment to find good parameters for speed, acceleration, etc.

To get PWM working, I had to improvise quite a kludge using an old Soviet (!) quad-NAND-IC, first inverting the laser on signal, then NAND-ing PWM and laser on, then inverting the result again. Yeah, I know. But it works for now. :)

I did notice a few issues:
- The "laser on" polarity parameter in the config file does not seem to have any effect! I had to invert it through external logic.
- "Move" function pretty useless. It accelerates really slowly and movement continues for quite a while after I let go of the joystick.
- Transfer fails sometimes when connected by WiFi, resulting in a hanging MBED.
- 3d Engrave either takes really, REALLY long or hangs - not sure which - while sending to LAOS. Hard to say.

I am waiting for another member of our lab to return from his vacation, when he does he will hopefully help fix some issues in the firmware and customize some stuff for us. I am not much of a coder.

I will upload our config file and make some changes to the wiki once I figured out optimum values.

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