Re: Stewart platform kinematics (genhexkins)

[Andy Anderson <afa_mma-at-ameritech.net>]

Till,

Thank you for your comments, and for the offer of your transformations. 
I might ask you for them later. For now I am just thinking, not building.

Are there any more pictures or papers describing your Primodell 
machines? I'm interested in building a small hobby machine. The 
Primodell designs are interesting.

Thanks,
Andy Anderson

Till Franitza wrote:
> Hallo Andy!
> What you talked about is referred to as Inverse influence in SIEMENS jargon.
> When using spherical joints or specially designed kardanic joints you do not
> have this effect. I have never written a kinematic transformation that
> handles this, but i think it is not too difficult. The kinematics
> transformations of emc have not been looked at for a longer time, while the
> call to the function has changed. I recently implemented kinematic
> transformations for my 2 machines
> http://www.isw.uni-stuttgart.de/personen/t_franit/primodell/index.html and i
> found i had to change the names of the variables in respect to older
> versions. This is because emc supports 5axis-milling now.
> Emc does the forward trafo quite often. This is very time consuming so you
> might want to comment it out. EMC always displays the position in cartesian
> coordinates that are calculated from the actual position values of the
> motors. It would be easy to comment this out and just use the commanded
> position for display. It is done like that on real machines that i know. On
> my real-world machine ( linapod 3 on www.dynamil.de) the forward kins are
> only calculated once when the motors are turned on. After that the control
> just sends commanded values to the motor controllers and assumes the
> controllers keep them to display precision.
> for the callinc conventions of kins just look at trivkins.
> Do you want me to send a sample of my trafo?
> Till
>