Building Robots at School

September 29, 2009

VEX Motor Curves

Filed under: Uncategorized — dtengineering @ 7:35 pm

Motor power curves are very important when designing robots.  They are more important in competitions such as FRC, where you can choose from different motors, than in VEX, where you only get to use one type of motor, but it is still nice to see some published data on what the little motors can do.  The maximum torque specified in the manual is about .75Nm, but looking at the curves published on the VEX Forum by jgraber, the maximum in practice is closer to .5Nm.  Of course you won’t see .5Nm on there anywhere as the figures are in English units, but the data is valid regardless.  Note the relatively flat power curve… you get roughly the same amount of power from the motor over a range from about 40-80 rpm.  Typically DC motors are happier running at high rpm as they have a lower current draw, which means they stay cooler and last longer… so I’d recommend planning to run your VEX motors at about 70rpm and 2.25 inch pounds of torque.  (That’s about 0.25 Nm).

Should you ever need a quick unit conversion… say from inch pounds to newton metres, just go to google and ask “2.25 inch pounds in newton metres”.  It’s spooky what Google can do!

VEX Motor Curve

VEX Motor Curve

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