View Single Post
  #20   Spotlight this post!  
Unread 23-12-2004, 08:26
Max Lobovsky's Avatar
Max Lobovsky Max Lobovsky is offline
Fold em oval!
FRC #1257 (Parallel Universe)
Team Role: College Student
 
Join Date: Jan 2004
Rookie Year: 2004
Location: Scotch Plains, NJ
Posts: 1,026
Max Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant futureMax Lobovsky has a brilliant future
Send a message via AIM to Max Lobovsky
Re: Victors Non-linear!!!

Quote:
Originally Posted by Rickertsen2
This would be true if a motor were strictly a resistor but it is not.
Power output of a motor at a given time is given by:
power = ((V-speed*kv)^2)/armature resistance
where speed is in rads/sec and Kv is the motor's CEMF speed constant.
as you can see power output is not porportional to the square of voltage unless you assume your robot is always moving at a single speed.
But isn't speed proportional to voltage for a given load? (ie speed=V*someConstant). In that case, we have

power = ((V-V*k*kv)^2)/armature resistance
and hence
power = ((V*(1-k*kv))^2)/armature resistance



Anyway, I think there is some very obvious and simple evidence that your data is wrong. I would guess that most of the community gathered data for RPM/torque/current curves were gathered using Victors to control voltage, and all these curves report the expected linear curve, and therefore, the Victor must be outputting a linear voltage.
__________________
Learn, edit, inspire: The FIRSTwiki.
Team 1257


2005 NYC Regional - 2nd seed, Xerox Creativity Award, Autodesk Visualization Award
2005 Chesapeake Regional - Engineering Inspiration Award
2004 Chesapeake Regional - Rookie Inspiration award
2004 NJ Regional - Team Spirit Award