hey guys,
i have an absolute accuracy question. We recently acquired KUKA KR420R3080 with KRC4 extended. The robot has the absolute accuracy sticker on it.
In the commissioning process we measured straightness and orthogonality of the robot, although the straightness is within 0.1mm deviations, orthogonality is terrible.
Test setup:
We used marble block whose orthogonality according to standards, see pics. One edge of the triangular block was aligned with World-X of the robot and the other edge with the World-Y axis of the robot.
Using dial indicator deviations were measured. The indicator was attached on the flange of the robot.
First on the top of the block we moved the robot +-200mm in both X and Y direction (block's top surface is coincident with World-XY plane of the robot). Deviations in this test in World-Z direction were within limits of 0.1mm which is to be expected, I think. Then we moved the robot on one side of the block, the side coinciding with the World-YZ plane along World-Y direction. In this test as well the deviation in were within 0.1mm. Lastly to check orthogonality we moved the robot in World-XZ plane in World-X direction. In this measurement though the deviation is within few millimeters.
see pictures of the marble block.
Since we are planning to use KUKA.cnc, program was created in KUKA.cnc.
cnc code:
NC code
(Along X direction)
G01 G90 X862 Y1219 Z593 A0 B0 C180 F1000
G01 G90 X1062 Y1219 Z593 A0 B0 C180 F1000
G01 G90 X862 Y1219 Z593 A0 B0 C180 F1000
(Along y direction)
G01 G90 X862 Y1219 Z593 A0 B0 C180 F1000
G01 G90 X1062 Y1219 Z593 A0 B0 C180 F1000
G01 G90 X862 Y1219 Z593 A0 B0 C180 F1000
For comparison a KRC program was created to repeat the same motion, dat file of the KRC program given below.
KRC .dat file Cartesian coordinates
;Along X direction
XP1={X 862.008301,Y 1219.00073,Z 592.997742,A 2.44405310E-05,B 0.000963584229,C -179.999847,S 18,T 35,E1 2.10471456E-38,E2 0.0,E3 0.0,E4 0.0,E5 0.0,E6 0.0}
XP2={X 1062.008301,Y 1219.00073,Z 592.997742,A 2.44405310E-05,B 0.000963584229,C -179.999847,S 18,T 35,E1 2.10471456E-38,E2 0.0,E3 0.0,E4 0.0,E5 0.0,E6 0.0}
XP3={X 862.008301,Y 1219.00073,Z 592.997742,A 2.44405310E-05,B 0.000963584229,C -179.999847,S 18,T 35,E1 2.10471456E-38,E2 0.0,E3 0.0,E4 0.0,E5 0.0,E6 0.0}
;Along Y direction
XP1={X 862.008301,Y 1219.00073,Z 592.997742,A 2.44405310E-05,B 0.000963584229,C -179.999847,S 18,T 35,E1 2.10471456E-38,E2 0.0,E3 0.0,E4 0.0,E5 0.0,E6 0.0}
XP2={X 862.008301,Y 1419.00073,Z 592.997742,A 2.44405310E-05,B 0.000963584229,C -179.999847,S 18,T 35,E1 2.10471456E-38,E2 0.0,E3 0.0,E4 0.0,E5 0.0,E6 0.0}
XP3={X 862.008301,Y 1219.00073,Z 592.997742,A 2.44405310E-05,B 0.000963584229,C -179.999847,S 18,T 35,E1 2.10471456E-38,E2 0.0,E3 0.0,E4 0.0,E5 0.0,E6 0.0}
Here also deviations were different when executing motion from KUKA.cnc and KRC.
Axes of ISG were configured with the axconfigurator. Am i missing some configuration steps?
Am i misunderstanding absolute accuracy?
Should the robot be recalibrated?
And is this setting factory setting or something has happed while transporting?
Thanks