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The basic characteristics of DC motors
I'm sure most people on this thread are aware by now, but torque/rpm curves of DC electric motors are MUCH DIFFERENT from those of internal combustion engines. The basics of the motors, at constant voltage input are:
1) The maximum torque of the electric motors is at zero rpm (stalled)
2) The torque, and the current draw of the motor are inversely proportional to the RPM as controlled by load
3) The maximum power output of the motor occurs at about half the no-load rpm
While it has little to do with our robots, it is interesting to note that most electric vehicles such as golf carts, fork trucks, and pure electric cars do not use gear change. For those purposes, you can get adequate acceleration at low speed while using gearing selected mainly for desired 'high speed' operation.
With our robots, though, it is desirable to go as fast as possible, but also be able to push and pull very hard at low speed. Changing gears makes this possible without pulling lots of motor damaging and breaker tripping current from our motors.
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Team 45, TechnoKats, 1996-2002
Team 1062, The Storm, 2003
Team 233, "The Pink Team," 2004-present
The views I express here are mine, and mine alone, not those of my team, FIRST, or my previous teams.
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