Hi Dingo - You will have to find a clever maths person who can do a jacobian transfer of the co-ordinates so a std 3 axis system output can be translated into the cylindrical co-ords of your system. Maybe a lathe output will work. But I think you will find that over such a big radial distance the accuracy required in the X rotation to achieve normal tolerances at the Y end will be quite tricky and the crane beam will be quite wobbly. Both of these factors will be hard to resolve mechanically and mathematically. Plus your rotational momentum of the Y axis will be enormous requiring a very large motor to get it going and to stop it. You will need to look at these numbers very closely to avoid disappointment.

There are machines called SCARA look them up they may be helpful and motion controllers exist for these. Your concept has many challenges and maybe building a small scale one first is the 2020 project....Peter