Relocating base coordinates

[Kurt]

Has anybody successfully relocated a base orgin and have the programmed points move/shift accurately to the new base location. I have done this numerous times with KUKA robots but I have not been successful with Denso. I always end up having to touch up each point. I have 6 robots on very similar machines (not exact due to machining tolerances) and I want to run the same programs on all robots without performing touchups on hundreds of points. In theory I should be able to just teach my base coordinates and my points should shift accordingly....not so. Denso techs advised to touch up points. This would be a good feature if robots required swapping out also.

[AA Robotics]

Hi Kurt

Have you tried the wizard tool to calculate the work coordinates? Program 3 points one at the Origin, one in the +X plane and one in the +X +Y plane. You need to do this when the robot is set to work 0. You can then run the wizard and it will calculate the new coordinates.

I have not tried it to match 6 robot programs but do not see why it would not work. I use the function to align a camera field of view to the robot for vision based calibration and it works fine.

The robots are calibrated so you should also be able to down load the program into any robot and it will run in the same place. There are obviously limits to the tolerances on any system, probably the tool to faceplate interface will be the most unreliable.

If you have a manual then setting section 4.1 should explain it.

[MBIautomation]

Hello Kurt,

I have done just what you have explained for a dispensing program that contains 100's of points, duplicated to 4 machines. I used the three point method that Neil Described to create a work coordinate.

Orgin= 0,0
Point on X = + Value on X axis
Point on XY Plane= + value in X and Y direction

I then created a Teach Pendant screen that allows the operator to simply edit each element of the work coordinate (x,y,z,Rx,Ry,Rz) which moves the entire program in the desired direction.

In this situation they needed to adjust the entire program on a regular basis due to dispensing variables, if you would only use it during maintenance then the TP screen may be overkill.

You can also use Wincaps III to find the origin of your work coordinate if your work cell is in 3D cad. This allows you to visualize exactly where the work coordinate will be be.

Here is a snipit of the line of code that edits the coordinate elements.
The I Variables are the numeric variables being set in the TP Screen created to make editing the values easier.
The work coordinate starts out as (100,100,0,0,0,90) and then is modified with the I variables.

Work 1, (100+I[10],100+I[11],I[12],I[13],I[14],90+I[15])
Changework 1

Orgin-0,0
Point on X = + Value on X axis
Point on XY Plane= + value in X and Y direction

Hope that helps...

[Kurt]

Thanks for the help! I have used the wizard for base offsets using the 3 point method. The points did move in the general direction I wanted but not exactly what I wanted. The points I have programmed have to be very exact (within 1-2mm). I carefully calset the robot thinking that may be my problem. I even made a sharp pointer for the EOAT for teaching the (3) points. I also made a base plate with the 3 points scribed on the plate then moved the plate about a 1/2" in each direction and used the wizard to see if the points would follow. Some of the programmed points associated with that base were off by at least 3/8". I tried using the tought TCP of the pointer before teaching the base too. Also used T0 flange before using the wizard. If I only needed 1 point to move I probably could get the offset to work but I have dozens of points. It seams like the controller is not calculating the new points correctly.  What kind of tolerance/precision should I expect? The robots I have were used and I do not know their history. I have (2) brand new robots and controllers on the way. I will perform more testing on those. With a competitors robot, I only had to teach the 3 base points to establish the base location. I have moved bases and have had preprogrammed points follow exactly (<1mm). I guess I need to know if I am expecting too much of the Denso, or am I doing something wrong. If a robot arm should go bad, I ought to be able to swap the arm and reteach the bases and all my programmed points should be right on again. Two techs at Denso encouraged me to spend my time reteaching the precise points in this situation.