Correction of rotary axis

[TFrenken]

Hello,
I use your Kogna board with KMotionCNC for a retrofit on a Hermle UWF 1000. I am planning on using the geo correction table for X and Y axis with Z offset. But is there a possibility to compensate for non linear errors in rotary axis as well?

Regards,
Thomas

[TomKerekes]

Hi Thomas,

How would that work? Would the corrections be a function of XY? Or of the Corresponding Angle?

Our Geppetto 6 axes cable robot calibrates the C angle (rotation about Z) as a function of XY. See the function:

int CKinematicsGeppettoExtrude::GeoCorrect(double x, double y, double z, double a, double b, double c,
double *rx, double *ry, double *rz, double *ra, double *rb, double *rc)

[TFrenken]

Hi Tom,

thanks for the quick reply. As of now I would only like to be able to correct mechanical positioning errors of rotary axis. As those errors are non linear, I need some kind of correction table with corrections to the angular position at intervals between 0° and 360°. For example if 90° is of by 0,1° I would like to correct that by software to achieve the measured 90° correctly.

Another great use case for this are swivel rotary axis that use a ballscrew as actuator (older DMU 50 for example). In this case the angular position of the axis is a non linear function of the signal to the servomotor and will have a few mechanical errors as well. Maybe it is even possible to to combine both functionalities.

I would really like to use KMotionCNC and kogna for all my retrofit projects and this is the first situation in which I felt like there might be some feature missing in the current version.

Regards,
Thomas

[TomKerekes]

Hi Thomas,

It seems like that would be a 1 dimensional correction somewhat like screw mapping.

That could be added to the Kinematic Class.

Give us some time and we will try to come up with a patch to add that feature.

[TomKerekes]

Hi Thomas,

Here is a patch for V5.3.3 that should add a Table mapping feature to a linear Axis such as this:

There is a description in our wiki here.

The change is to the Kinematics in the GCodeInterpreter.dll Library.

Download and copy this file to the \KMotion5.3.2\KMotion\Release folder.

GCodeInterpreter.dll

Please let us know of any issues.

[TFrenken]

Hi Tom,
I honestly did not expect to see this function implemented this fast. Thank you very much! Your support is beyond words. I will test this function as soon as the machine is ready for measurements.

Regards,
Thomas