# KUKA 7th Linear axis????

• Hi,
We are having a KUKA KRC4 6 axis with Linear 7th axis robot. Till now I have worked only with KUKA 6axis robots and this is my first time with KUKA linear 7th axis integration. So I am having some doubts.

1. The difference between Synchronus and Asychronous movement?
Syn- All the 7 axis will move to reach the destination point. We must teach it the point with E6POS
Asyn- My Linear 7th move according to E1 in E6POS and then the robot will work with remaining 6axis.

Have I understood it correctly. If not, please correct me.

2. In sync movement. What is the meaning of mathematically coupled and mathematically uncoupled External axis?

3.First I need to do the Mastering of the External axis. Can I also do the mastering of the Linear 7th axis with Electronic dial gauge connected to X32?

CONFIGRATION:
4. What are the configrations setting need to be done in machine.dat file for sync move.

Programming
5. I must declare all the position datatypes as E6POS and the value for my 7th axis will be stored in E1 for Sync Mathematically coupled? or XYZ will be calculated from the reference of the Linear 7th axis?

I hope, you can understand my questions. If not, Plz ask.

• Mathematically coupled: The 7th axis is part of the robot's motion model, influencing the speed and direction of TCP motion. This requires that the kinematic relationship of the 7th axis to \$ROBROOT be well-calibrated. This allows a rail-mounted robot to move along the rail while continuously welding a seam, or allows the robot to "follow" a part that is rotating on a 7th-axis turntable while continuously welding on it non-stop.

If the 7th axis is not mathematically coupled, this is not possible. However, time synchronous motion is still possible -- if the 7th axis is commanded to move as part of a PTP motion of A1-A6, then all 7 axes will begin and end their motion at the same time -- if the 7th axis is faster than A1-A6, it will slow down to match the speed of the slowest axis. If E1 is slower than A1-A6, then A1-A6 will slow down to let E1 keep up.

However, even if the E1 axis is synchronous, without mathematical coupling, any LIN or CIRC motion will not be able to take E1's motion into account. So a LIN motion that drives A1-A6 and E1 may result in a TCP motion that looks more like a PTP move.

Asynchronous external axes are usually decoupled from A1-A6 motion, and can be moved by separate commands (ASYPTP). This makes it possible to command an external axis to do something that has no effect on A1-A6 motion, and is unaffected by A1-A6 motion. In effect, the external axis acts somewhat as if it were another, independent machine. A PTP motion driving A1-A6, and an ASYPTP motion driving E1, can execute in parallel but are "invisible" to each other, running independently and at their own speed and timing. Sometimes this is useful, sometimes it can create serious collision risks if you're not careful.

In some configurations, an asynchronous external axis can be controlled by the SPS instead of the main interpreter, and can become an almost entirely separate machine, with no interaction with the main interpreter unless you add handshaking between the programs.

As far as I understood:

There are two types of motion for external axis:
Sync and Async

Sync: All the 7axis(if we are having only 1 external axis) will move together to reach the destination point. Under this Sync it's further subdivided to mathematically coupled and mathematically uncoupled. Mathematically coupled- It's used for a dynamic base, it needs to be calibrated. Mathematically uncoupled- It's used for a static base and it doesn't need to be calibrated.

Async: moves the external axis independently from robot6axis. For this, async needs to be activated in dat file.

For sync, mathematically uncoupled and linear axis:
1. From the workvisual; Select your linear external kuka axis from the catalog and add it in hardware configuration area.Then goto geometry tab and click proposal. then give ok. If will do all the configuration parameters.

2. Transfer it to controller.

3. Master your KUKA linear external axis also.

4. In program the points datatype is E6POS

Have I understood correctly????? If not please correct it.

• For a standard model KUKA external axis unit (KL1500, etc), this should be broadly correct. For an external axis that is not a regular KUKA catalog product, a greater degree of manual data entry and calibration is required.

• Thank you for the detailed explanation! Is there an official document from KUKA that contains the instructions on how to program additional axes? I couldn't find any on KUKA's official website.

• Did you check Xpert? It is near bottom of pinned topic READ FIRST