Re: Probing

["Dean L. Hedin" <dhedin2001-at-home.com>]

On Wednesday 16 January 2002 12:03 pm, Carl Mikkelsen wrote:

> No, I'm doing everything with homebrew software and Linux.  I wrote a
> kernel driver that does 6-axis coordinated movement in hexapod leg
> coordinate system, and fronted that with a user-mode process which breaks
> linear 6-axis Cartesian movements (XYZPRW) into leg movements.
>

I thought everybody was using EMC for the hexapods.

> > > This is a picture of my probe...
> http://www.foxkid.net/cgi-bin/next-res.pl?home_album=/Processed/Carl%27s%20
>Projects&basedir=./Processed/Carl%27s%20Projects/Stewart%20Platform/Truck%20
>Signs&res=svga&name=PA250761.JPG&album_name=Truck%20Signs

I saw this when I was browsing the web earlier.  Pretty slick.

> It would be pretty simple within my software to take the Z-axis
> interpolation I'm doing now and change it to output a normal vector to the
> surface along which the cut should be made.  My Stewart Platform machine
> has limits on the angles, depending on where in the working volume the tool
> need to be.  

Is that the typical approach, to calculate surface normals and set
yaw, roll , and pitch of the head?  XYZ and YRP are completely
independant for the entire range of motion?


After looking at your setup I have a few more questions...
1) What are the aluminum sections on the 3 sides of the triangular head?
2) Your angle limits are a result of the arms hitting the motor at certain
     positions?
3) I assume your are using steppers as linear actuators,  this being the case,
    while you are cutting across a flat plane all  steppers must be  running..
    Are there problems with resonance?
4) I'd like to see a picture that shows the entire "cage".
    

>How curved a surface are you intending?

With my my 3-axis router, just gentle curves.


>
> Sounds like tk/tcl is the tool of choice.  Is there any code you'ld
> recommend I read to learn it?

Here's a good start:
http://www.objenv.com/cetus/oo_tcl_tk.html


>
> -- Carl
>
>
> Carl Mikkelsen
> cmm-at-alum.mit.edu
> www.foxkid.net