Non-standard external axis control

Started by arthurprior, February 22, 2022, 08:51:12 PM

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Hi All,

I have a question regarding the use of non-standard motors for external axes. The motor must have a 40 mm frame side (i.e motor flange width) and be controlled synchronously (i.e. by using E1... values in the main program).

Option 1:

Using a KSD (Kuka Servo Drive) with a smaller servo motor

The smallest compatible external axis servo motor offered by KUKA is MG_8_40_45_S0 (Art No. 00-131-269).
This motor is basically a Siemens 1FK7 motor (exact part No. is 1FK7022-5AK71-1YH3-Z S24).

Looking at the 1FK7 data sheet ...

There is a smaller motor (20 mm shaft height) within the range: 1FK7015-5AK7. This is the size I want to use. It also is rated for 600 VDC.
If I modify the part number to get a smaller frame size I have:
1FK7015-5AK71-1YH3-Z S24
which is shown on the Siemens website:

... but ...
It appears some of the part numbers can't be identified within the Siemens catalogue (they are proprietary to KUKA).
"Y" "Z S24"

I have contacted Kuka and Siemens, but neither of them are cooperative and give information about the resolver type "Y" and whatever "Z S24" is.
Does anyone have any insights?

Option 2:

Can anyone suggest a way of controlling the position of an external axis by reading the E1 values ($AXIS_ACT_MEAS / $AXIS_MOT ?) and using them to control an external motor via a PLC.
So far it has been hard to find info about the how virtual axes work...

Any help greatly appreciated :)

Johannes @ Robots in Architecture

Hello Arthur,

I came across your thread on robot-forum ( and don't really have anything to add beyond what panic_mode posted...

Sorry that I cannot help you with that!


Regarding your first option, it seems you're facing challenges with identifying the specific characteristics of the Siemens motor variants used by KUKA. Unfortunately, the proprietary nature of certain part numbers can make it difficult to obtain detailed information from either KUKA or Siemens directly. However, you may consider reaching out to Siemens directly or searching for technical documentation or forums specific to Siemens motors to see if you can find more information about the resolver type "Y" and the "Z S24" designation.

As for your second option, controlling the position of an external axis using E1 values from the main program and a PLC is indeed feasible. Here's a basic outline of how you could approach this:

Read E1 Values: Use the PLC to read the E1 values (e.g., $AXIS_ACT_MEAS) from the main program of your KUKA robot controller. These values represent the actual position of the external axis.

Convert to Desired Format: Depending on the communication protocol and requirements of your external motor, you may need to convert the E1 values to a format compatible with the PLC and the motor controller. This could involve scaling, data formatting, or unit conversion as necessary.

Send Commands to External Motor: Once you have the E1 values in the desired format, use the PLC to send control commands to the external motor controller. This could involve sending position commands, velocity commands, or torque commands depending on the control mode and capabilities of the motor controller.

Feedback and Closed-Loop Control: Implement feedback mechanisms in the PLC to receive status updates or feedback signals from the external motor controller. This allows for closed-loop control and monitoring of the external axis position to ensure accuracy and stability. Kroger feedback entry code

Testing and Calibration: Thoroughly test the system to ensure that the external axis movement aligns with the desired motion commanded by the KUKA robot controller. Calibrate the system as needed to account for any discrepancies or inaccuracies.

By following these steps and leveraging the capabilities of your PLC and external motor controller, you should be able to effectively control the position of the external axis using E1 values from the KUKA robot controller.