View Single Post
  #26   Spotlight this post!  
Unread 03-12-2012, 10:37
Ether's Avatar
Ether Ether is offline
systems engineer (retired)
no team
 
Join Date: Nov 2009
Rookie Year: 1969
Location: US
Posts: 8,120
Ether has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond repute
Re: Balancing an Arm

Quote:
Originally Posted by Andrew Schreiber View Post
Reducing speed in software is going to make your motor run harder.
^This.

Here's a rather contrived example, but it illustrates the point.

Suppose you are using a BB550 motor to raise an arm, and you want to drive the arm at 15 rpm (90 degrees per second) at a torque of 500 oz-in.

If the total mechanical speed reduction from motor output shaft to arm rotation is 10:1 you'll be drawing ~60 amps

If the total mechanical speed reduction from motor output shaft to arm rotation is 50:1 you'll be drawing ~12 amps