Move the machine during operation

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09 Aug 2011 10:58 #12330 by andypugh
What might work would be to use HAL "offset" components between the position commands and the stepgens during program execution to compensate for tool wear, then write the final values of the offsets into the tool table and reset them on program completion.

This won't work for tool diameter compensation during milling, though.

I think that a clever kinematics file could do diameter compensation, as long as a way could be found for the kinematics module to determine whether left-side or right-side compensation is active.

It might even be possible to modify EMC2 to allow on-the-fly tool diameter compensation. I will ask on the developer mailing list.

C is C, whether is it compiling for a uP or a PC.
This is the simplest possible kinematics module:
git.linuxcnc.org/gitweb?p=emc2.git;a=blo...590a69b5bce9e31a0ae1
Whereas this is a modified kinematics for 5-axis work:
git.linuxcnc.org/gitweb?p=emc2.git;a=blo...590a69b5bce9e31a0ae1
And this is a massively complicated one for arbitrary serial robots:
git.linuxcnc.org/gitweb?p=emc2.git;a=blo...590a69b5bce9e31a0ae1

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09 Aug 2011 11:28 #12332 by btvpimill
If you choose the uP route (I think better to work it out in EMC, but time may be against you for the learning curve), run the step/dir signals through the uP. Find a pin in HAL to signal to the uP there is new step/dir data and pass it to your drives. Then to move while the machine is moving, have the uP monitor your input device, and send more steps when you want to. Don't forget to keep passing the EMC data so the other joints keep moving where they should.

Keep in mind, EMC will have NO idea you have changed the actual position of the joint, So moves close the the end of travel will likely crash.

Care to shed some light on what situation will cause you to do this? If you are trying to creat a "floating" head for example, I think there are ways for that.

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09 Aug 2011 18:47 #12349 by dzarek
maybe it is possible execution Home Z using Gcode ?

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09 Aug 2011 19:09 #12352 by BigJohnT
It's possible in a round-a-bout way using M1xx commands to execute a HAL pin.

John

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12 Aug 2011 07:07 #12446 by dzarek
is that enough for me:)
I test the home forcing in command M1xx and ultimately improve dxf2gcode so that put me to the command before attaching cutting :D

Thank you very much for your help, in case of further problems I'll ask ;)

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