Closed jahnj0584 closed 7 years ago
chamnit
commented
7 years ago Yes. That's what the max and min rpm settings are for, which assumes a linear relationship. If you need a nonlinear fit, there is a config option for that. See the Python script for how to set the constants for it.
massiveradiation
commented
6 years ago I know this is closed. I'm new to python and I'm trying to setup the non-linear curve for my super-pid, but am having troubles. When I copy paste the python code into the web site given, I get errors. The first one is a syntax error on line "file main.py" line 26. Sorry, I've been looking around for someone to teach a newbie like me how to do this, but I'm coming up empty handed. I'd love to create a youtube video of the process if I can figure it out. Thank you for all the hard work you're doing on grbl! I use it all the time. Fantastic stuff. I just want to be able to enter an "S" value in g-code and have my pid go to the same rpm. I understand that the speeds to voltage output of the arduino are not linear of course and I get the concept of entering a series of input value vs real rpm based on tach readings. I just don't know how to get the script to run. If there is information other than the instructions provided, I'd happy to read through them if you can point me in the right direction. A summary of step by step would be so helpful. Example:
chamnit
commented
6 years ago I copy and pasted the fit_nonlinear_spindle.py in the /doc/script folder into the repl.it webpage. It ran fine. If you edited the file, you may have introduced a syntax error.
massiveradiation
commented
6 years ago Thank you for getting back to me so quickly! Hmmm. I didn't edit it. On that page, do I need to "add file," name it, then cut and paste into new file? Leave the main.py blank? Also, which version of the fit_nonlinear_spindle.py should I use, there are several. Can you give me a link? I think I have the latest one. It doesn't seem to like the two lines of "+" next after the """
massiveradiation
commented
6 years ago Hmmm, maybe it's because it doesn't give me an option to choose, "Python REPL." Also, I'm pasting into a file, not sure what the "browse editor" is, as you've specified. Sorry, very green...
massiveradiation
commented
6 years ago chamnit
commented
6 years ago Looks like they changed how repl.it works since the last time I used it. Copy and paste the raw text of the fit_nonlinear_spindle.py file into main.py. Create a dummy file in repl.it so that the generated image will appear after you run it. Just click the "Add File" button. Name the file anything. Doesn't matter. Just leave it blank. Then go back to main.py and click run. You should get some text output and an image file (png) will appear in the file list.
massiveradiation
commented
6 years ago Aaaaaaah! Let me try...
massiveradiation
commented
6 years ago YES! That was it! Now, I see the output and the image file. Thank you soooo much. One more question while I have your attention, there are other sections of the site, one referring to buffer underrun etc. Do I need to change my other grbl files with those? If so, where do I alter the file, place at beginning? Does that make sense?
massiveradiation
commented
6 years ago And should my $30=1 and $31=255? Make changes only to cpu_map.h? So if there is an M3S10000 command grbl interprets it and translates to a pwm value between 0 and 255? Sorry, just trying to wrap my head around this.
chamnit
commented
6 years ago No, you're not making any sense. Default grbl should work fine. The only things you should change are standard $$ settings and in the config.h, which contains more advanced options like enabling the nonlinear spindle part of the code. You shouldn't mess with cpu_map.h or any other file.
Max and min rpm values are arbitrary. Set them to whatever you want. Usually you'd make them close to real world values.
massiveradiation
commented
6 years ago Sorry if I'm not making sense. Here is my output with default. Down below it says to alter the cpu_map.h file and the defaults.h: Python 3.6.1 (default, Dec 2015, 13:05:11) [GCC 4.8.2] on linux
CONFIG: N_pieces: 4 PWM_min: 2.0 PWM_max: 254.0 PWM_point1: 20.0 PWM_point2: 80.0 PWM_point3: 150.0 N_data: 15 PWM_set: [ 2. 18. 36. 55. 73. 91. 109. 127. 146. 164. 182. 200. 218. 237. 254.] RPM_measured: [ 213. 5420. 7145. 8282. 9165. 9765. 10100. 10500. 10700. 10900.
SOLUTION:
[Update these #define values and uncomment] [ENABLE_PIECEWISE_LINEAR_SPINDLE in config.h.]
[To operate over full model range, manually write these] ['$' settings or alter values in defaults.h. Grbl will] [operate between min($30,RPM_MAX) and max($31,RPM_MIN)] $30=11681.7 (rpm max) $31=203.5 (rpm min)
[Update the following #define values in cpu_map.h]
PCPayne
commented
6 years ago Hi Guys, i started a new issue few days ago about connecting my laser. Can anybody help me at all please.
massiveradiation
commented
6 years ago Thanks again chamnit! I'll play around with it now based on what you've said.
massiveradiation
commented
6 years ago Is there a reason there is a period after the 213 in the RPM array?
chamnit
commented
6 years ago @massiveradiation : The period denotes a floating point value in Python. Otherwise, it can sometimes interpret it as an integer.
massiveradiation
commented
6 years ago Shall I start getting router tach values with $30=254 $31=1? Then later, after config.h is changed with nonlinear adjustment, change to actual rpm values? In the sample array entries, it appears that's what's being done. I'm just trying to figure out the best strategy.
massiveradiation
commented
6 years ago Got it working. Pretty damn close. I set $30=254 and $31=1 an collected 15 data points of rpm. For the record I tried to use about 20 data points and the results were whacky! Is this what is meant by using only 4 pieces? Not sure. After copy and pasting the results of the script, I changed $30 and $31 to min/max values listed in the results. It's good, but I think some more well thought out data points in the rpm range will yield closer results. Thanks again for your help! I'll create a video of the process and post to my youtube channel, wiremonkey: https://www.youtube.com/channel/UCKwyc01hSo3kpFYGm77d0rw?view_as=subscriber
chamnit
commented
6 years ago Adding more data points shouldn't change the fit algorithm. Can you share the setup parts of your python script and the plot? I'd like to see if there was something else that caused the problem.
A piece-wise linear approximation with four line should be good enough for mildly nonlinear curves, especially if you set your intersection points well. Adding one or two more lines may be possible, but it isn't something that important for a general release.
massiveradiation
commented
6 years ago Interesting. Maybe I did something else wrong. It's easy to get lost when entering a ton of data. I'll try again. the result gave me a massive rpm min of over 600K! Thanks again for this. So cool!
Sonny Jeon mailto:notifications@github.com April 6, 2018 at 4:34 PM
Adding more data points shouldn't change the fit algorithm. Can you share the setup parts of your python script and the plot? I'd like to see if there was something else that caused the problem.
A piece-wise linear approximation with four line should be good enough for mildly nonlinear curves, especially if you set your intersection points well. Adding one or two more lines may be possible, but it isn't something that important for a general release.
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Any way to calibrate the PWM to match real world values? I only read 4.7v instead of 5 nominal with the multimeter so the spindle is running 2-400rpm below what is is programmed to do. What is the best way to calibrate this so software matches the hardware?