Test if callibration of IRB6400 S4C is still ok

Simotion

I will have to commision an IRB6400 robot with S4C controller.
The customer bought the robot second hand.
How can I easily check if the callibration of the axes is stil ok.
I do not know if they changed or disconnected motors on the robot.

SjoLi

See if the Motor OFfsets in the parameters are equal to the value's mentioned on the inside of the cabinet on a sticker.

then set a MoveABSJ to [[0,0,0,0,0,0],[0,0,0,0,0,0]] ...

this should put the robot axis on zero. The notches (for revolutioncounters) should line up everywhere.

If this look OK try to see if the robot moves in a straight line when moving lineair.

Then you can check if a lineair movement of 1000 mm more or less equals 1000 real mm

Simotion

When you do the MoveABSJ, how much may the notches differ from the line up point (It will never be exactly).?The robot is an IRB6400.
What tolerance could we expect if we move the robot lineair 1000 mm : 1 mm, 2mm or more?

SjoLi

The notches should line up visibly. If they line up 50/50 probably there is an error (motor offset valu in the partameters could be one of them)

The deviation from the 1000 mm is not realy important (2/3/4/5 millimeters), as long as it is a straight line, the deviation probably also changes depending on the location (close t or far from the robot).

Probably you will be jogging the robot to a position and teach it into a programed point. After this it is the repeatability that counts. And if the path you programmed softwarematically is 998 or 1005 mm does not realy matter.

The robot is precise but probabl not true (see understanding link).

http://www.ndt-ed.org/GeneralResources/ErrorAnalysis/UncertaintyTerms.htm