Soemething a little different

Hi everyone,

My colleague at university requires an interesting axis combination whereby 1 axis is coupled to another but also free to move. This is like placing one linear axis on another (parallel to each other) and then having the 2nd axis follow the first but also able to move independent of the first. He cannot simply mount one axis on top of the other so I said i would take a look at whether this can be easily implemented in Linuxcnc. Ive never looked at the gantry kins but was thinking there might be some clues in there. My initial thought is the kinematics would be modified so
joint 1 = a + joint 0 i.e axis 2 follows axis 1 and moves additionally by some amount a. Do you think this can be done?

Thanks
Anthony

Thanks for the Reply Andy. Hmm all good points and i need to find out more from him. In the meantime do you think it can all be done in the kinematics file, i think I can manage this, otherwise probably too hard basket.

Thanks
Anthony

Ok, thanks Andy. I just found the below reply of yours to another user from a couple of years back and im wondering what the rational for doing this type of compensation in HAL over kins is?

Thanks

forum.linuxcnc.org/10-advanced-configura...ensation-with-2-7-11

What is the advantage of doing these compensations in Hal over kinematics? More accurate

It would look a bit like this:
component wobbly_table;
pin in float x-in;
pin in float y-in;
pin in float z-in;
pin out float z-out;
function _;
;;

FUNCTION(_){
zout = z_in + 0.1 * x_in + 0.2 * y_in + 0.01 * x_in * y_in;
}

linuxcnc.org/docs/2.7/html/hal/comp.html