Stepper Motor Positioning Question/Brainstorm

[michrod1234]

Hi all!

So I am new to this forum and this question may or may not be answered already or in the incorrect spot. Please let me know if either of those are true

Okay...so I'm starting a project and will be using a stepper motor for the first time. Problem is...I didn't realize that stepper motors can't give feedback and tell me their position? I thought about switching to a servo, but it doesn't quite fit the needs of my project.

But I DO need some kind of way to know the position of the stepper I'll be using. I need to add 'something' to it. I thought about using a compass, but I'm wondering if anyone with more experience has any better ideas? A friend of mine suggested an encoder...but I'm not really sure how that would work and couldn't find a detailed enough resource on the internetz.

Any ideas?

Appreciated!

 

[Pommie]

Normally, whatever the stepper is driving has a home position with a microswitch. For example, a cnc miller would have a lead screw and would initially be driven to the home position and that would be used as the zero position.

You'll get a much better idea after reading a few threads over at https://www.cnczone.com

Mike.

 

[alec_t]

But I DO need some kind of way to know the position of the stepper

What angular resolution do you need? How many steps per rev does your motor have?

 

[shortbus=]

If your motor has a double ended shaft, an encoder or resolver can be fitted to it.

 

[Mr RB]

You "know" the position of a stepper motor by keeping track of what step you have moved it to previously. Unless there is a massive fault load the stepper motor will not "lose steps".

If you also need to know the starting position you can use a single sensor like an optical or hall effect sensor. In some applications they just juse a mechanical endstop, and on startup just move the stepper motor as far as it can go (which hits the endstop) then after that its position is known.