help to set up the kinematics

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18 Apr 2011 11:01 #9039 by honey
I am a new user and I have no experience with these things..so I thank those of you who will help me and will have the patience to answer my questions.

I have a 6 axis robotic arm and i want insert the kinematics of this arm. Can i do this? Which files and how i must change them?

If it possible, you can write me step by step how I should do?

Thank you

Francesca

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19 Apr 2011 11:02 #9073 by honey
Replied by honey on topic help to set up the kinematics
So....For custom kinematics I should edit only the "pins" in the HAL were created by the pumakins or genserkins kinematics module? like this
setp pumakins.A2 200
setp pumakins.A3 300
setp pumakins.D3 100
setp pumakins.D4 500

Or I should edit for example pumakins.h or pumakins.c and then recompile emc2?

Sorry if my questions are so stupid :(

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19 Apr 2011 12:29 #9078 by BigJohnT
Your questions are not stupid.

This is the kinematics docs.

www.linuxcnc.org/docview/html/motion_kinematics.html

I don't really understand it all but I do know where the docs are...

John

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20 Apr 2011 18:26 #9181 by andypugh
honey wrote:

So....For custom kinematics I should edit only the "pins" in the HAL were created by the pumakins or genserkins kinematics module? like this
setp pumakins.A2 200
setp pumakins.A3 300
setp pumakins.D3 100
setp pumakins.D4 500

Or I should edit for example pumakins.h or pumakins.c and then recompile emc2?

Sorry if my questions are so stupid :(


If your robot is a Puma layout, then putting the correct setting is as above should do the trick.

You will need to set up the actuator limits and scales too, of course.

You only need to recompile if you are creating your own completely custom kinematics (and genserkins should cover just about any eventuality really)

I assume you have already spotted the sample Puma configuration?

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21 Apr 2011 07:55 - 21 Apr 2011 07:57 #9214 by honey
Replied by honey on topic help to set up the kinematics

andypugh wrote:

If your robot is a Puma layout, then putting the correct setting is as above should do the trick.

You will need to set up the actuator limits and scales too, of course.

You only need to recompile if you are creating your own completely custom kinematics (and genserkins should cover just about any eventuality really)

I assume you have already spotted the sample Puma configuration?



I have an Armdroid 1 Robot....
Then I could set correctly genserkins module with the parameters of my robot without recompile? in this way should it work?
Last edit: 21 Apr 2011 07:57 by honey.

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21 Apr 2011 09:06 #9215 by andypugh
honey wrote:I have an Armdroid 1 Robot....[/quote]

That looks very much like a Puma. By setting the pumakins parameters correctly you might well be able to get the required kinematics.

Otherwise genserkins ought to work (just because it has a lot more parameters).
The drawback is that you need to figure out the Denavit-Hartenberg parameters:
en.wikipedia.org/wiki/Denavit-Hartenberg_Parameters
Has a nice video.

I think in your case it is all fairly easy.
Joint 0 has zero for all parameters.
Joint 1 has alpha = pi/2 d = offset, alpha = 0, r = 0
joint 2 has alpha = 0, theta = 0 , d=0, r = upper-arm length,
joint 3 has alpha = 0, theta = 0. d = 0, r = forearm arm length
joint 4 has alpha =0, theta = pi/2 d= wrist joint offset r = 0

But that is just a guess. You probably need to swap the signs of some angles, swap some d and r terms. that sort of thing.. I have never actually derived DH parameters or used genserkins.

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24 Jul 2011 20:41 #11800 by honey
Replied by honey on topic help to set up the kinematics
Ok, I have used genserkins module and I set it with the parameters of my robot. But i have a problem.... my axis x not corresponds to joint 0 as well as axis y to joint 1 and so on...!! Where and how i can make the right corrispondence? i must create some lines in hal for resolve this problem?

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24 Jul 2011 20:51 #11801 by PKM
Replied by PKM on topic help to set up the kinematics
What do you mean by "right correspondence"? Does the robot move at all, what's wrong? Describe what you have.

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24 Jul 2011 21:20 #11803 by honey
Replied by honey on topic help to set up the kinematics
Ok I try to explain to me better or maybe my problem doesn't exist. I am not so expert! However for example the JOINT 0 would corrispond to the base of robot. The axis that moves the base in my case is axis A. So this would be a problem if i used genserkins module? in this module JOINT 0 is assigned to axis X?
I ask this because my robot don't move if i write a MDI command line.

Sorry if i make confusion....i am new user of this software!

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25 Jul 2011 10:42 - 25 Jul 2011 11:01 #11818 by honey
Replied by honey on topic help to set up the kinematics
My robot work correctly when i use the manual mode (so the forward kinematic i suppose!) but it doesn't work when i use the auto o mdi command (inverse kinematic?). So i thought that this problem could be due to Axis/joint corrispondence or something wrong in hal section.
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Last edit: 25 Jul 2011 11:01 by honey.

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