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T800_412
Posts: 51 Apprentice
How to work around snapshot position calibration pose problems |
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Answered | |
/ Most recent by David_Gariepy
in Programming
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10 comments |
Is there a best practices method to get around having to do snapshot position calibration? I would like to do a cam locate with the UR10 positioned where the camera is horizontal, and the UR10 arm is very close to joint limits and some mechanical obstructions. If I do a normal calibrate from there, the arm will either hit the obstruction, or the joints will collide and stop the robot.
I tried calibrating with board laid horizontal so the arm can move freely, but get error messages that the arm will not be able to reach all the calculated poses.
I tried calibrating with board laid horizontal so the arm can move freely, but get error messages that the arm will not be able to reach all the calculated poses.
Snapshot Position will determine the field of view, notice that the calibration step position does not have to be the same as Snapshot position. Thus, you can have a small field of view, then move back for calibration step.
Calibration board position.
Figure 7.3.1 : Calibration board position.
Specification
Value
UR3
UR5
UR10
Vicosystems S.L.L.
Industrial Collaborative Systems
[email protected]
[email protected]
The wheel I want to inspect is positioned as you would see a tire on a car, so the camera is looking at it from the side to see the full diameter of it. I could put the calibration board higher off the table, and further away from the robot base, which would then allow the arm to move around as it needs to for calibration. Will that work?
With my initial attempt at doing this, the copied snapshot position, when trying to find the object in parametric teach, it cannot be located. Is that do to the 30mm offset in Z?
If you create a new snapshot position by copying another snapshot, you have to use the same workplan.
Objects to detect should be placed on the plan where you previously placed the calibration board.
Create a snapshot position from scratch using the calibration board to define your workplane where you don't have reach issue with the robot. Then create a snapshot position by copying the snapshot you previously created.
The first step remain the definition of the workplan. For this step, you have to find a place where you don't have reach issue to perform the calibration.
If you cannot find a place without reach issue to do the calibration, you cannot setup the camera.
The following function will allow offsetting a calibration in a program
snapshot_position_offset = p[x,y,z,rx,ry,rz]
For example, the following will offset the calibration 100MM+ in the X direction from the robot base
snapshot_position_offset = p[0.1,0,0,0,0,0]
This function should be used with the ignore_snapshot_position=True function
This means you can calibrate a snapshot position and teach a part beside the production location, then offset it to the desired position.
Note that this will affect precision and is working only for x,y,z variation. Any rotation of Rx,Ry,Rz won't be affected.
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