Kinematic model for a 5axis mill with universal (nutating) head

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14 May 2023 08:01 - 21 Jan 2024 12:31 #271334 by Aciera
3rd UPDATE :
The zip folder below now contains two configs:
1. Table rotary C - spindle rotary B - spindle rotating (nutating 0..90°) A
2. Table rotary B - spindle rotary C - spindle rotating (nutating 0..90°) A

The spindle setup is defined in a [TWP] section in the ini file.

 

I have expanded the original config and documentation to a generic configuration with variable nutation angles 0-90°.
Also the Tilted Work Plane (TWP) section in the documentation has been expanded.
Note that that the TWP remap is still fairly experimental!

 

 

File Attachment:

File Name: table-rota...g.tar.gz
File Size:768 KB


ORIGINAL POST:

This is from work I've been doing to derive a kinematic model for a milling machine with a 45° nutating head like this one:




Notes:
1. TCP kinematic works
2. TOOL kinematics work also but there are some quirks that I have not been able to figure out. Like an odd behavior when issuing an incremental move immediately after switching to tool kinematics.
3. The attempted implementation of 'Tilted Work Plane' GCode is still rather experimental and would need a fair bit more work.
4. The config requires a custom vismach.py file for visualisation.
5. This kinematics requires version 2.10pre (ie master)
6. Documentation is included in the config folder as an html document.
 

 

File Attachment:

File Name: spindle-ro...g.tar.gz
File Size:218 KB

Maybe somebody finds this useful
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Last edit: 21 Jan 2024 12:31 by Aciera. Reason: 3rd update
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27 Jun 2023 08:55 #274301 by grandixximo
This is coolest thing i've seen in a while, I'll have to study the configuration, congratulations man, looks amazing!
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27 Jun 2023 14:40 #274307 by Aciera

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27 Jun 2023 14:49 - 27 Jun 2023 15:10 #274308 by Aciera
Last edit: 27 Jun 2023 15:10 by Aciera.
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18 Nov 2023 05:42 - 18 Nov 2023 05:43 #285796 by Gurpreet
Hi, I'm trying to understand the matrix math to create the kinematics for 50 degree nutating spindle. It's a XYZAC with spindle rotating and nutating, fixed table machine.

I'm following the manual found in the attachment. I'm stuck in the Inverse transformation section. Please see attached picture of the formula.

Could you please explain what that mean.

Thanks

 


 
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Last edit: 18 Nov 2023 05:43 by Gurpreet.

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18 Nov 2023 07:03 #285798 by Aciera
That would be the transpose of the rotation matrix for the table rotary C.
Since you have a fixed table and an AC spindle rotary assembly you would omit the C table rotation in my writeup and replace the B spindle rotation with a C spindle rotation (ie you would have 'Rc' instead of 'Rb' on the spindle side).
Also there is a typo in my write up: both of the lower two formulas are for inverse transformation (P_A_Q) and not just the last one.
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18 Nov 2023 07:27 #285799 by grandixximo
From ChatGPT an explaination of teansposed matrix
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19 Nov 2023 01:54 - 19 Nov 2023 02:02 #285875 by Gurpreet
Please see attached picture for the rotary head configuration.After removing the C axis from the table side and replacing B axis with C axis on the spindle side, C axis looking good in simulation, but only when Rotary A is at home position.After changing the angle of Rotary A, TCP start to create narrow oval.Do I have to change (Rotary A) transformation matrix as well.     
 

This browser does not support PDFs. Please download the PDF to view it: Download PDF

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Last edit: 19 Nov 2023 02:02 by Gurpreet.

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19 Nov 2023 08:32 - 19 Nov 2023 08:42 #285881 by Aciera
I can't read the numbers in the data sheet but if your nutation axis is not 45° then you would need to change the rotation matrix for A using the formula in my documentation.
I would suggest to start with the A axis (C = 0°) and work backwards. You will also need to think about which geometrical offsets are going to be relevant in your particular assembly.

[edit]
This section is where you will need to adjust for angles other than 45°.
 
Note that in your case you may not be able to use a simple algebraic expression like 1 over the square root of two.
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Last edit: 19 Nov 2023 08:42 by Aciera.

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20 Nov 2023 00:30 #285979 by grandixximo
He provided PDF that is readable at the end of the post, and the B axis is indeed at 50° 

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