[gavztheouch]

Plotting postional error while running code in mach?

Would it be possible to use Kflop to output the postional error while running some gcode in mach or KmotionCNC.

The motors would be steppers in an open loop and there would be a glass scale on the gantry to measure postion. Kflop would ideally be running in open loop, so not trying to correct the errors in postion just noting down what the errors are in say a spreadsheet?

This would be good for visualising current errors in my machine, so when I make mods to the mechanicals of the router I can see what improvements have been made to the accuracy.

It would also be great to see the difference in the accuracy in the machine when air cutting in comparison to a variety of different materials for example hardwood vs foam.

You could take it a step forward and also place a rotary enocoder on the stepper to measure any missed steps. Would it be possible to output postional error from two encoders on the one axis?

Cheers

Gav

[ger21]

Since you already have the capability, why not just run it in closed loop mode?

[gavztheouch]

Since you already have the capability, why not just run it in closed loop mode?

Mainly out of interest, I have a sloppy machine that is giving errors of 0.2mm and above. I would like to get the mechanicals better before running in closed loop.

[TomKerekes]

Hi Gav,

You can do this. I do it all the time to find problems. There are some example C Programs to capture data and then upload it to a disk file. See the example:

C:\KMotion430j\C Programs\CaptureXYZMotionToFile.c

That example just captures the commanded x,y,z trajectory but you can easily modify it to capture encoder Positions also. If you are using KMotionCNC it is easy to assign the program to an MCode so then you can move the MCode around to capture different areas of GCode.

There is another Example I use a lot that collects data into a circular buffer and then detects some type of Trigger event such as a large following error. So then it uploads what happened before and after the trigger point:

C:\KMotion430j\C Programs\CaptureXYZMotionTrigger.c

You need some way of plotting the data. I use Excel and set things up so by just refreshing the data the plot updates.

You can capture up to 8MBytes of data at a time. It can be every 180us Time slice or every N Time slices.

HTH
Regards
TK