Hi all, pe2023's point is a good one and it was a question I had...

Hi all,
pe2023's point is a good one and it was a question I had as well, I couldn't get my head around how you were going to get a non flat slab to have a true structure built on it, but it is all in how the technology works.
Michael explained to me  that the steadiness of the boom occurred because it was referenced by a 3 degrees of freedom laser scanner transmitting a beam, from a  known location bound to the earth, just like a theodolite ,and then the laser pointing to the tip of the laying head, was reflected back to the base scanner by another 3 degrees of freedom active mirror. So in effect the whole boom was referenced to a physical location, in 6 degrees of freedom ie x,y,z, and roll, pitch, and yaw, from there it was all simple matter of putting a laser reflector on a staff at each wall direction change,  noting the height discrepancies and then let the program calculate the offsets required to  get the slab footings level and to build a square and true structure off them. As he pointed out the footings didn't need to be true and flat as the robot did the correction on the first few courses and trued the structure from there up, just like a brickie would. So long as the base laser never moved then everything became relative to its location. After about the 3rd course even the worst slab height differences could be corrected.
The patent is very clear on how all this works and certainly worth looking at, I have to admit it made more sense to me once I had talked with one of the inventors as he was able to put things  in much simpler terms , but the concept is pretty cute.

"Hanzo" brings up a valid point  about the size of the machine on site, which from what I can gather is why the second machine needs to be built. The current machine is way to big and as Michael pointed out when he spoke to me, it was all about finding a base to build from that was cheap and would allow a proof of concept to be built that would show it was possible to stabilize the laying head at the end of a  30m flat stick boom. ( this one stuns me, its amazing how this works), they didn't want to spend  $100's of thousands of dollars on building a specific custom system.... I get the impression money was very tight in the early days and  it was all about proving it could be done rather than building the ideal machine for all applications.
This aside he thought that even the current machine would work on most sites so long as there was a suitable setback from the road to the closest front wall.

I think tilt up panels will always be a competing technology, but I am not sure I would want to live in  a house made out of them, but that's my personal preference.
There is however a really interesting technology I found in the USA
http://www.psfk.com/2014/12/concrete-3d-printer.html
This is all about a concrete extrusion head that layer by layer creates extruded block like wall structure.
it would seem , from my reading about this technology, that the big hurdle for them is getting a steady extrusion head. They use this massive gantry system which I suspect makes life difficult on any size block..

Imagine the concrete head these guys have developed  attached to the head of the fast brick robot, what a combination... tilt ups would cease to exist overnight...