AKD2G Dual Loop

Closing the Position Loop with External Feedback for AKD2G

This app note explains how to configure the AKD2G drive to close position loop on an external encoder.  It includes instruction for linear encoders and rotary encoders.

Background

For most users, closing the position loop using an external encoder is used so feedback is generated directly from the application, rather than the rotary motor driving the application. Some benefits to using an external encoder are:

• Higher positioning precision is directly linked to the application which can support any backlash that may be seen on the motor’s side.
• Having the ability to use encoders that fit closer to the application’s needs (i.e. linear encoders for linear applications)
• Increased confidence the system is behaving as intended.

Key Takeaways

• Set which feedback will be used to close the position loop. This can be set in the Feedback screen under the Axis’ Settings. For more details see the “Setting the external feedback to close the position loop” section of this document below.
• Determine the scaling factor (PIN and POUT values) by using the Units screen and entering the systems mechanics. For more details see the “Scaling for external linear feedback – Units Screen” section of this document below.
• Using the PIN and POUT values from the Units screen, set the AXIS#.PL.KFB.PIN and AXIS#.PL.KFB.POUT to scale the physical system. For more details see the “Scaling for external linear feedback – AXIS#.PL.KFB” section of this document below.
• Scaling for external rotary feedback is a different approach compared to linear encoders. For more details see the “Scaling for external rotary feedback – AXIS#.PL.KFB” section of this document below.
• Set AXIS#.MOTOR.PITCH to 1 in the terminal screen
• Use the AXIS#.PL.KFB.PIN to set the direction of the system.

See the link below to go to the app note.

Secondary Feedback Loop App Note RevB.pdf