Pally 2.10.0: Bug: robot won't pick the box

Users of Pally 2.10.0 may experience the following incorrect behaviour:

  • robot moves to pick position with high speed

  • vacuum is turned on

  • an error message “Failed to control the robot after picking box” appears in the log

  • vacuum is turned off immediately

  • robot proceeds without holding the box

  • the above steps are repeated one or more times

This error can be observed with all of these grippers that can be controlled by Pally:

  • Schmalz FXCB

  • Unigripper CoLight

  • Custom Vacuum Gripper

  • other special grippers defined by a gripper.json file


Another appearance of the same bug can be observed in projects where the gripper is controlled by user code in callbacks:

  • robot moves to the pick position (typically with high speed)

  • vacuum is turned on by user code in beforeGrab callback

  • robot picks the box

  • robot moves the box to the pallet position

  • box counter is not increased, the robot will try to palletize the same position over and over again

This error can be observed with all of these grippers that are controlled by user code:

  • Custom gripper

  • Custom vacuum gripper


Currently the following workaround is possible:

  • set the following two parameters by adding script lines in the initial MoveJ node:

    • rf_joint_deviation_max=0

    • rf_joint_deviation_err=0