We have had some issue with IRB360 picking behind an item on a conveyor.
Our system is Pickmaster using vision for detecting itmes on a pick conveyor, placing to an I/O triggered indexed place work area. We have two IRB360 Flexpickers in line picking from the belt.
Several paramters effect the problem,
- The position of the product on the conveyor has to be past the 0 point of the robot (product moving away from the robot). The further away from the robot (towards the conveyor exit limit) the greater the pick position error.
- Place Time (In the indexed work area settings). The longer the place time the greater the pick position error.
- The setting of Adjustment Speed to 130% of conveyor speed gives the biggest error of about 100mm with a place time of 0.2sec
(Topics/Process/Conveyor Systems/CNV1). Increasing to 800 (at 22m/min) 220% of conveyor speed, give a reduced pick position error of about 5mm with a place time of 0.2sec.
If we have a place time of 0.001 sec then we see no visable error in the pick position.
We have this problem on at least 5 different lines, the line the results were recorded from has been calibrated and verified this week.
Has any one else seen this type of problem and is adjusting the adjustment speed above the 130% of conveyor speed the right way to fix this problem?
Many Thanks
Mark
Hi Mark,
Have you check you camera calibration with the calibration check paper? What are the result?
What is the mean error of you base frame calibration?
Is there any disturbance on you encoder signal?
Have you improve you conveyour tracking settings ?
We usualy set these values in our conveyor tracking to get more accuracy :
Parameter
|
Standard
Value
|
Our set values
|
ABB
Suggestion
|
Remarks
|
Corvec correction level
|
1
|
3
|
3
|
MOC_ROBOT
|
DN_C1Interval (4-20)
|
20
|
10
|
20
|
EIO_UNIT_TYPE - d377A
|
IIRFPeriod (0.004-0.02)
|
0.02
|
0.01
|
0.02
|
EIO_COMMAND - Fieldbus command
|
IIRFFP (12-20)
|
2
|
15
|
15
|
EIO_COMMAND - Fieldbus command
|
Pos_update_time (4-20)
|
20
|
10
|
20
|
PROC_CONVEYOR_CAN_SENSOR
|
adjustement_speed
|
400
|
850
|
850
|
PROC_CONVEYOR (1400 voor IRB360)
|
sync_filter_speed_ratio
|
0.8
|
0.5
|
0.8
|
PROC_CONVEYOR
|
Acc_dependent_filter_value
|
1
|
0
|
0
|
PROC_CONVEYOR
|
Correction_vector_stop_ramp
|
X
|
10
|
10
|
PROC_CONVEYOR
|
BR,
Fabrice
Hi,
Have you checked the counts per meter is correct?
If this is accuratly set then as Fabrice has suggested it could be interference on the encoder wiring (most commonly from vairiable speed drives).
BR
Graeme
Hi,
Thank’s for the reply’s. The counts per meter is ok and the verification was good ± 1mm.
We considered noise on the encoder wiring, which is screened. The error in picking is very predicatable and only produces an error in the + x (robot picking product which is moving away from the robot). I would expect an encoder noise problem to be random and effecting all of the conveyor work area. I will try the suggested parameters which I know some are not set to the values suggested.
Thanks
Mark
I have tried using the ABB suggested values, these correct the picking error up to a place time of 0.2 secs, above 0.2 secs an error appears again. This however fixes our problem untill we ever need to have a place time greater than 0.2 secs.
Thanks for your help
Mark