Stepper motor position feedback

Hi,
Im currently in the process of upgrading my diy motion control 3 axis camera slider.

Im trying to recreate as many features as possible that are present in the much more expensive edelkrone slider systems (https://edelkrone.com/)

With this commercial product, you are able to set in and out points for the slider movements by manually moving the slider (like this at 6:39 Advanced Camera Motion Control | Edelkrone SliderPLUS & HeadPLUS - YouTube).

As you can see in the attached photo, this system uses a NEMA 8 motor with a worm drive system. Initially I assumed the stepper had some sort of encoder but then after seeing the insides of this product and seeing that a worm gear is used I became very confused at how the slider is able to move at all.

Does anyone have any idea how this position tracking is done within the edelkrone slider and how I would be able to accomplish this?

Image from Original Post so we don't have to download it. See this Simple Image Posting Guide

...R

I don't see a worm gear in your photo, but I will take your word for it.

I had a brief look at the video and I can only assume that manually moving the system automatically disengages the worm drive and uses some other system for measuring the distance moved. It would be possible to measure movement with a free wheel running on the slider track and attached to a rotary encoder. But probably not so easy to implement with reliability and precision.

...R

Hope the worm drive is clearer in this photo, correct me if you don't think it is a worm drive.

worm drive.png

How do you reckon they automatically disengage the driver?

Also does anyone know the name of the gear the worm mates with, specifically the curved type shown in the photo?

Thanks for your help

worm drive.png

tomdixo:
Hope the worm drive is clearer in this photo, correct me if you don't think it is a worm drive.

I don't see a worm gear. And you can get reversible worms. Or it might be a bevel gear system.

How do you reckon they automatically disengage the driver?

Sorry, I have no idea.

...R