closed feedback loop?

Controllers Smoothie
1

hi all, my first post and question.

can the smoothieboard system be used for closed feedback loops on the three axis? 4 if you include 2 Z axis motors (would save them running apart over time).

e.g. a stepper ‘counter’ motor, that counts the steps, if steps are missed add the step in etc. or the old optical sencer and ticker rape ribon, or even steppers with the old counter built in…howed yu imploment it?

i’ve read till i’m blue in de face! the basic answer so far iz ooooooo bee-elsibubbut marks n spencer sell pink undies, or some such read up. so? can any one actualy answer the question? the worst replies apply to the notion of ‘its a hobby…the hobby is spending money not actualy getting a productive unit…’

smoothieboard? can it imploment closed loop feedback?

side question, if yes

what are the comands/G or M codes to do so, how / where do yu plug things in?

sorry to be a pain but it is a simple question lol… i care not to weather steppers are fantastic and how they work etc etc etc lol….basic fact, have you seen the resolution to a pc printer? look at the letters in fine print? hell of an accurate isnt it? no look at how shoddy the slide guides and bearing system is…ermmm that shouldnt print tiney little letters at that speed no way no how should it?
so…the diference being the feedback loop…i’m really intrested in it….really. but cant get a straight answer after 3 years looking into it…hellup? hellup?

Imported from wikidot

2

Hey there.

To answer your question simply : Smoothie does not have closed loop support.

Nowhere is it claimed it does. We do not hide anything, it’s obvious to many that Smoothie controls stepper motors, if it’s not obvious to you, don’t wait 3 years : just ask.

While the board itself does not have servo control support, you can get closed-loop control from Smoothie very easily by using external “servo”-type drivers, that are controlled the exact same way stepper drivers are controlled.

I’d like to add that you are completely wrong about closed/open loop and accuracy.

You can definitely get the exact same accuracies with comparable stepper or servo setups

And for a given accuracy, servo setups tend to be much more expensive ( but you get the added benefit of error detection/correction ).

3

hey, thank you for a straight answer.

my main concern was with correcting the missing steps…

can you illaberate a little with the external bits? i can get hold of pritty cheap, or cheaply… steppers that are used to count steps as a feed back.(3 quid a axis…)

4

Smoothie breaks out the step/direction/enable signals for each axis. This will allow you to interface with most external motor drivers, both stepper and servo.