genserkins for 5-DoF robotic arm

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18 Jul 2021 14:01 #215227 by elisa
Hello everybody,

I would like to use "genserkins" kinematics for my 5-DoF robotic arm.
However, "genserkins" needs at least 6 axes.

How can I deal with it?

Do you know specific kinematics for 5 axes serial machines?



Please reply me soon!

Thank you.

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18 Jul 2021 16:51 - 18 Jul 2021 16:52 #215240 by Aciera
It's been a while since I set up my robot. I wonder if maybe you could try to set up the DH parameters of the genserkins kinematic so that two joints coincide (ie. make one line of parameters zero).
Forward kinematics should be ok but I have no idea how the inverse kinematic will react.
You could install current master and modify the "melfa-sim" config.
Last edit: 18 Jul 2021 16:52 by Aciera.

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19 Jul 2021 09:45 #215301 by Aciera
I've tried to set up genserkins for a 5 DOF arm. Forward kinematics seems to work but the inverse kinematics totally fails.

So I'm afraid you would have to come up with your own kinematic. I'd try to figure out the math by using this (and yes you will need to make yourself familiar with matrices):

alvarestech.com/temp/RoboAseaIRB6S2-Fiat...s-serial-robot-2.pdf

and maybe this excel document:

github.com/Chris-Annin/AR2/blob/master/A...nematic%20model.xlsm


Then you can look at pumakins.c in the linuxcnc/src/emc/kinematics folder for an implementation.

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29 Jul 2021 20:50 - 29 Jul 2021 20:54 #216268 by andypugh
Making a length of zero is probably causing mathematical problems.
But you could have a "dummy" joint at one end of the chain, and simply not drive it.
Scratch that idea, the inverse kins would want to use it in the solutions.

scorbot-kins seems to be 5 DOF: github.com/LinuxCNC/linuxcnc/blob/master...atics/scorbot-kins.c
Last edit: 29 Jul 2021 20:54 by andypugh.

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