Belt Driven Actuator

[norm1978]

I plan to build an custom actuator driven by a servo motor with using a toothed belt. The load I want to move is 50 Kg on a distance of 48 inches with the speed of 6 m/s. How I should size the servo motor?


Thanck

 

[Skogsgurra]

It depends a lot. Are you moving vertically or horisontally? What acceleration do you need? What positional accuracy? What friction is there?
I think that you should check with servo system suppliers. They have compter programs where you just answer a set of questions and get the motor, gear, drive, encoder etc that does the work.

Gunnar Englund

http://www.gke.org

 

[Barry1961]

Keep the reflected inertia ratio less than 10:1 is the main thing.

Also make sure the temperature of the servo is not a problem to the incoming wiring or gearbox it connects too.

As a loose rule I like to keep motor speed under 3000 rpm for noise among other things.

If you are using a belt make sure you size by tooth shear and not tensile. The best belt I have used for applications like yours is Gates PolyChain. They make special sprockets with a pitch diameter slightly above calculated if you want to reduce slop. I always just turned down the OD a few thousandths to tighten it up.

There are a couple of spreadsheets for sizing servos at:

http://www.skadrives.com/engineering.htm

You can get in trouble with these very quickly if you start guessing at inertias. Most people don’t have a feel for inertia and it is very easy to guess off by a factor of 100 or more.

Give some more info on the load and acceleration.

Barry1961

 

[norm1978]

I want to use it horisontally with pricision of 0.250''
I hope that can be usefull...

 

[fsmyth]

Most reputable vendors have an excellent treatise on sizing
available. Check places like Baldor, MicroSyn, etc...

50 kg is a sizable load. Consider wrapped cable, especially
if you have considerable acceleration. 1/4" resolution is a
non-issue. Think old daisy-wheel printers. You may be able
to salvage all the parts you need off one if you can find
one still around, and the electronics are included.

<als>

 

[waross]

Take the radius of the drive wheel you intend to use and the load you intend to lift. With a litle arithmetic, you can calculate the ft. lbs. of torque required.
Now divide your belt speed by the circumference of the drive wheel and you have the RPM's required. Check your textbook for the formula to derive Hp. from torque and RPM.
Don't forget to add a safety factor, and don't mix up seconds and minutes in your calculations.
yours

 

[Barry1961]

What acceleration or cycle time do you want? Making a few guesses I am coming up with around 3g acceleration.

Barry1961

 

[norm1978]

I want for cycle 0.5s ( 48 inches x2 forward and reverse) every 8 seconds.