Non-trivial kinematics problem

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25 Feb 2010 13:18 #2060 by subtractive
I have built, and am running a 3 axis cnc router, with another machine build on the way. The
control software, in FreeBASIC, gives excellent motor speed and positional accuracy. Trajectory
planning and constant feed are the main missing features.

I have known about Linux/EMC for a number of years, and recently took advantage of the user
friendly CD install, that provides Ubuntu 8.04 and EMC2. In addition, the Config Wizards for my
servo motors, motor drivers, limit switches, etc., were straightforward and must be praised by
anyone who uses them. The whole software package, a result of many years work by many people,
is a credit to you all! There are two computers, with suitable latency test results, both
loaded with EMC2 ready to run my routers. If my machines was using trivial kinematics in all 3
axes, that would be the end of it!

The machine z axis is trivial with respect to the Cartesian z axis. The Cartesian x and y axes
are handled, mechanically, by two separate rotary axes, similar to a SCARA robot, but not the
same!
My intention was to insert my own non-trivial equations into the C functions that make up a HAL
component. The learning process is rewarding when you know what the goal is. I am entirely
self-taught in this whole project and my programming skills are limited to using one of the
BASIC dialects. I have tried in the past to move on with other languages but had to give up.
There is just too much unknown syntax and terminology for me. There is no question that EMC2
will be running my machines but I am stuck and need rescuing. Would someone help me please?
Subtractive

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25 Feb 2010 22:31 #2065 by alex_joni

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26 Feb 2010 11:05 #2072 by subtractive
Thank's for your time and expert help , Alex. I shall do my best to understand your guidance.
I understand all the concepts in the Integrator Manual kinematics chapter 27. Just not
familiar with the syntax or notation which I assume is C code but I'm sure I will manage.
As mentioned in my first message I have working equations ready to insert, but what
next.
Subtractive

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26 Feb 2010 12:47 #2076 by step4linux
You need to create a new kinematics c program.
Take one of the examples from EMC src/emc/kinematics and modify it.
I used trivkins.c as a base.

Once you created your c-file, lets call it mykinematic.c, you enter
comp --compile mykinematic.c
This will create mykinematic.ko
Install it by
sudo cp mykinematic.ko /usr/realtime-2.6.24-16-rtai/modules/emc2/

Modify the hal file
replace
loadrt trivkins
by
loadrt mykinematic

thats the procedure

another example you find here: http://code.google.com/p/emc2hotwinch/

rgds Gerd

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02 Mar 2010 20:58 #2155 by subtractive
Thanks for the helpfull guidance Gert.
Your information was short and to the point.
Looked at your hotwire website and it's very impressive given the cost.
I've been reading printouts of kinematics source code etc.
There is some studying to be done.
Once again thanks
Andy

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11 Mar 2010 09:13 #2273 by subtractive
After loading the scara type robot from the EMC2 Configuration Selector, I can
manually jog, but can't run any of the sample g code files. Is this normal.
Andy

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