Hi, we have a EA 1900 with a servo positioner. Today we crash it with a positioner. We can see that errors: Wrong Motor Rotation + Servo Tracking Error + Collision Detect. All in B axis. We lost the signal to center the B axis but we dont see it in 90º to R axis. Could be happened that B axis run away? How do we to fix it? Thanks!!!!!!!!!!! Camilo
Problem with B axis
-
Camilo Nievas -
October 30, 2018 at 12:06 AM -
Thread is marked as Resolved.
-
-
We lost the signal to center the B axis but we dont see it in 90º to R axis.What are you calling the signal to center the B-axis?
If you jog the B-axis to 0 pulse counts the alignment marks for the B-axis should line up. If not then the calibration is off. This is problem due to damage during the crash to the B-axis.
-
We moved the B axis to 0 pulses and it seemed that it moved. We adjust it to 90º and it is 1885 pulses that we take as new 0.
The problem is that we lost the reference stickers of the axes. Do you have a picture of where the marks of the center of the axes go to see if they are at 0?
Thank you!
-
If you look at the right side of the robot there should be a drop pinhole on the R-axis that lines up with a dimple on the B-axis. When aligned this would be the mechanical home position for the B-axis and 0 pulse counts.
-
Thanks, we moved the axis to the correct place and we have in pulses we have -1885. I attached some photos. What can we try to solve it? Thanks
-
You could modify the HOME POS for the B-axis. In the top picture are you at 0 or where you think 0 should be? From the top picture, it doesn't look like you are centered. Could be the perspective of the picture.
-
We recorded the HOME POS for the B-axis and it worked fine. Only that the pulses were changed. Internally the Axis B has a Clutch? or how could the pulse movements have happened?
Thank you
-
The B-axis has a separate motor, brake, and encoder. The motor has a pulley. The motor drives a toothed belt. The drive has a pulley. The toothed belt drives that pulley. The B-axis is a harmonic drive. You could look this up on wikipedia. The flex spline cup (bolted to the B-axis) is thin and has to flex. In a crash the flex spline cup twist. Since it is twisting, it is getting shorter. Eventually, the cup will not be able to engage the splines on the circular spline (bolted to R-axis) and the B-axis will flop around.
-
Sometimes the pulleys will slip. It is just a friction fit between the axle and the pulley, that's your clutch. If you remove the B side cover. Drive the B axis current position to zero. Make a mark on the pulley. Every time you come back to zero pulse counts, the marks on either pulley should be the same position. If the drive pulley is out, it's slipping. If the driven pulley is out the belt is jumping cogs. If they are both good but the b axis is not in the calibration marks, the drive is slipping or the driven pulley to the axle is slipping.
A harmonic drive will usually lose in a crash with a positioner.