[mvistein]

We are interested in evaluating the robot calibration features of RoboDK for KUKA robots. I therefore have two questions:

1. Our robots are already equipped with absolute accuracy from KUKA (“Absolutvermessen”), i.e. the KRC controller is already performing some position corrections. Is the usage of the RoboDK calibration function still worthwhile?
   
2. Furthermore, our robots are hanging from the ceiling on a linear track, and the position of the robots on the linear unit is not perfectly known. Does RoboDK provide any means for calibration of external axes?
   

[colinb83]

Hi Mvistein,

did your robot come calibrated from factory? if so was it also calibrated in the "hanging" position? if not then you wont be getting the best out of it, its always best to calibrate when the robot is installed in the location it will be working.

Robodk does have rail calibration in the calibration options

(note I'm not affiliated to RDK so please wait for an official answer from one of the guys in case I may be mistaken on anything)

[mvistein]

Hi Colinb83,

thanks for your reply.

yes, the robot came calibrated from the factory. I strongly assume that it was calibrated in the ceiling configuration, because this is a special ceiling variant (standard floor variants from KUKA cannot simply be turned around).

I'll have a look in the rail calibration function.

[colinb83]

Tbh the only way you will really be able to see how much improvement you can get from them is to do the actual calibration and verification, and see what the error is, either way its not a bad thing, you will either find your robot is nice and accurate and well calibrated, or you end up with a useful calibration, but at least you will know

[Albert]

I agree with Colin that to get best accuracy results it would be better to calibrate the robot once it is mounted on your cell. You can also calibrate external axes with RoboDK. Can you provide more information about your cell?

If your robot has already been calibrated using KUKA Absolute Calibration option it is important to disable this calibration. You can disable the calibration by setting the variable DEACTIVATE_ABS_ACCUR to TRUE in the $custom.dat file:

• $DEACTIVATE_ABS_ACCUR=TRUE
  

[mvistein]

Our cell consists of (amongst others) three KR 270 R2700 ultra C robots, mounted on a common linear track with a total length of approx. 30m. The linear unit is a KSL type (not KL) which is custom made by KUKA Systems. Some pictures can be seen under https://www.dlr.de/bt/en/desktopdefault....lery/33457

I'll have a look into the external axes calibration functions. Is there any specific documentation available? Unfortunately I didn't find anything about external axes in the offiicial documentation.

[Albert]

I'm sorry we took so long to get back. There's no documentation related to calibrating external axes. I recommend you to contact us by email and we'll do our best to help you.