Robot and Track not moving exact distances

  • I have an ABB IRB6400R s4c on a 14 metre track, I have attached a spindle to it to work as a CNC machine. I have been creating programs for the robot with a cad software and everything works, however im having problems with the robot not moving the correct set distances. over the distance of 10 metres it loses 15 mm. so when I tell it to move 10 meters it only moves 9985 mm. and this is causing problems with the robot cutting in the wrong places.


    What would be causing this? and is there anything to fix it?

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  • Is the track an ABB track?


    The info below applies only to the external axis. If the articulated arm is not moving as expected consider a service visit.


    The system parameter that requires changing is in the MOC topic and of the type Transmission.


    When a 3rd party's external axis is used (or ABB's if the move distance is incorrect) the steps below have produced satisfactory results. The process can be found in the Application manual - Servo gun tuning.


    Before messing with parameters be sure to create to make a backup.


    If the gear ratio is unknown, perform the following steps:


    ACCURATE measurement of distances traveled is vitally important!


    *Move the external axis some distance (1 meter should suffice). Read the jog position value on the FlexPendant. Make note of the distance, call this value A_jog_screen.


    *Accurately measure the traveled distance. Make note of the distance, call this value A_measured.


    *Move the external axis some farther distance (an additional meter should suffice). Read the jog position value on the FlexPendant. Make note of the distance, call this value B_jog_screen.


    *Accurately measure the overall traveled distance. Make note of the distance, call this value B_measured.


    *Read the value in Transmission Gear Ratio in the type Transmission. Call this value old_transm_joint.


    *Calculate the new transmission gear ratio value with the following equation:


    ((B_jog_screen - A_jog_screen)/(B_measured - A_measured)) * old_transm_joint


    Enter the calculated value in Transmission Gear Ratio in parameters. DO NOT CHANGE THE SIGN. If the original value is negative, ensure the new value is negative, same for a positive original value. Changing the sign will cause the external axis to move in the opposite direction!!


    *Restart the control.


    *Validate distance moved. Repeat process as needed.

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