I've set up a pick and place system.
After a poweroff (the next day) when I turn the robot on and calibrate it again, the coordinates are not the same as before. All axis are between 5 to 10 mm off.
I've tentioned the belts. I don't feel any play when the robot is powered on (maybe a little play but not much).
And it is with all axis so if one belt was loose you would see a difference in X or Y.
It is not a problem with the encoders because the program works fine when in operation. Only after power off it looses the coordinates and I have to teach all positions again. I have not found a pattern in it yet. So e.g. Z is 10 mm off every time.
Any ideas of what I'm doing wrong?
It is not usable this way.
If it is off by 4mm after powering off and back on I suspect the arm is moving slightly when powered off? as the motors do not have brakes it must remain undisturbed or be recalibrated. I am concerned that previously you said after calibration its off again. I would recommend replacing any damaged switches and adjust the calibration offsets using a digital level or angle gauge to ensure each axis is 0 or 90 degrees when in the home or "L" config and then when you are confident it is calibrated and all axis at 0 in the home position touch up your points and then verify it can repeat after recalibrating. Please keep me posted on this. You can also email me at info@anninrobotics.com as I check my email regularly and can respond more quickly.
OK I did that.
Calibrated the robot (I think this is required to get all the zero coordinates).
Loaded and ran my picker program. It was a bit off.
Tought the correct positions again.
Picker runs good again.
Loaded and ran rest program. Robot goes in vertical stand. It is not 90 degrees though. It is angled to the back at 80 degrees I'm guessing. See image below.
Powered it off.
Power on. Loaded and ran my picker program again.
It is off about 4 mm.
As I understand it calibration is required every time after power on to get zero values. Because the encoders are not abolute (closed loop?) but count from the start. That's what I read on the forum here.
I can make a video if that explains it better.
If you park the robot in the vertical rest position, power the robot off and back on without disturbing the arm position does it maintain position after powered back on? Is it only after a calibration that it is not retaining or losing position?