Why not to use a Stepper motor in DOF [ seen 8Nm - 15nM around 60$ ] ?

Hi,
Have anyone consider using a stepper motor instead of DC 12V motors with potenetiometers [ or whatever other windshield variant ] ?
In 3D printing this is the best possible solution [ good precission ] but disadventage they haven`t got enough torque [ around 1Nm ]. Lately have found something like this, a 8.4Nm, 6A - so could it be some pretendent to some ultimate solution [ 60$ ] ?
http://allegro.pl/silnik-krokowy-8-4nm-6a-86hs118-6004a14-cnc-i6714208577.html
Will probably need a controller, like this 4 motors 6A Toshiba [ 60$ ] http://allegro.pl/sterownik-silnikow-krokowych-toshiba-4x-tb6560ahq-i6116463308.html
Have anyone tried ?

I have some servo motors and a couple stepper, interested to see if you find anything

since some step motors has a required "torque" for a DOF and can be found in acceptable prices [ which also cannot be some sort of a disaster of course ] - then maybe could be worth to think about them someday [ still need to find more informations about this in practical usage and read a little more about this - also at the moment still not have enough free resources for a next build - when actually hasn`t closed my first 12V DC construction, yet... but it just crossed my mind that could / may be good solution for some future DOF builds, since theoretically we are building some kind of a step motor from a 12V DC with feedback from potentiometers just wanted to ask more experienced DOF builders, if someone had tried this idea. Maybe with controller on [ serial / usb ] - it could be used as interface in ST just without an arduino stuff...

This conversation comes up often - Steppers have their advantages/disadvantages for a sim - use the search - you would want a stepper with an encoder, or a system were it can 'home'. Personally -Steppers can be a bit too noisy for me.

I haven't got any real practical experience on whether they are effective in a motion system yet, but I have done some preliminary tests of driving a stepper with SimTools using an Arduino.



I plan to use a couple of these for belt tensioning soon, I'll report back with my findings when I do. This is a 3Nm stepper, I've felt a 13Nm model used as a DD wheel, and it is very strong for that purpose, but whether it's strong enough to move a whole rig, I'm not sure. Hopefully we'll get to find out soon

And yes, as SeatTime says, they are noisy!

Very nice !!!
You can use even 22 NM or more (NEMA 42) stepper, they really are powerful. I will follow your project, it's really interesting, and if you will share build information i will try too build this kind of motion. Thumbs up!

Hi Andrew, I have been considering using steppers as well; so what about a geared stepper?

Try this one: http://au.omc-stepperonline.com/gea...ared-stepper-motor-23hs222804spg47-p-147.html

R4egards Jerry

You won't be able to use the shaft as the main drive mechanism for the stepper, you will need to gear it down.
At this stage there is no way that a stepper motor is going to contend in a dollar for dollar performance contest in terms of driving a motion simulator.

Thank you Alexey, for clearing that up; so NO geared steppers (like the one mentioned) will perform properly in respect to a motion platform!

Regards Jerry

Hey Jerry, it's not that they wouldn't perform properly. Any motor with sufficient speed and torque should be fine. @Alexey was saying dollar for dollar on a cost basis.

The one you linked to lists very low rotation speed as a feature along with high torque. The low rotation speed could be an issue in a sim platform. Also, steppers need special driver electronics since the motor commutation is done electronically and you'd need a controller for each motor. They also generally need to be ramped up and down in speed which also slows overall response.

There probably are appropriate stepper motors and controllers out there but I bet Alexey is right that ones that are suitable will be very expensive especially compared to regular gearmotors.

A geared stepper will work, they are just slower.

Hi Zed, and thanks for making the reasoning on stepper motor usage clearer.

I appreciate every bit of guidance given.

Thank you
Jerry.

Hi Alexey, so slower in this case is not an effective pace?

I guess we are speaking of RPM!
At what RPM would an acceptable rotation need to be?

Jerry.

Hey Jerry, I don't have personal experience yet so grain of salt, but what I see mostly recommended are motors with outputs in the 50-60 rpm range. If you only use 90 degrees of travel on your output arms in a typical setup, neglecting acceleration and deceleration, that's 250 ms lock to lock.

That's not written in stone and I've seen mention of faster and slower motors here, but should be more or less a ballpark to aim for. Obviously the output gearing trades speed for torque. If you are moving lots of mass, you may want more torque which generally trades for less speed or more money.

Hi Pab61,

Can you share the code please ? Thank you

i was thinking about using a stepper as a ball screw motor

the problem i=I can see is the motors work in steps !

so it has to pulse x number if times to get from a to b

you can't use PID control to get to where you want to be faster

if you want speed a stepper motor is not suitable

they are perfect for CNC machines where speed is less important than precision

Too much vibration, too much noise, losing torque on higher speeds... just to name a few reasons...

That looks like a stepper and gearbox - do you know the gear ratio ?

It appears to perform pretty well !

So i could be suitable for a lever arm sim

Was this demo for a sim ?

No, its not suitable at all... I just used it to develop rolling average filter and spike filter for the AASD-15A servos...