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Unread 11-11-2005, 10:49
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Matt Leese Matt Leese is offline
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Re: Nintendo Style Speed Booster

Quote:
Originally Posted by Greg Needel
it really isn't limiting the power of the motors. since the IFI setup uses pwm(pulse width modulation) the motors are still receiving maximum voltage, it is just the pulse length that is shorter. and since
Torque(transmitted to the shaft) = (Horsepower*63000)/rpm

and since 1 HP = 745.699872 watts

and watts= voltage^2/ohms <--constant in this case because resistance of the motor doesn't change and neither does the voltage.

the total torque transmitted at a given rpm is the same, all that is being changed is your speed. This is the same thing that happens when you push the joysticks only a little bit forward.

we did this this past year and it works very well for precise movements on the field.


although to make a "speed boost" button you would have to be limiting your pwm the whole time except when you want to boost, which would be a waste.
This is wrong but I don't think I should delete it, just didn't want anyone to pay attention to it:

No they're not. To control the speed of a DC motor, you vary the voltage applied to it. PWM is used solely as a communication mechanism between the RC and the speed controller. It's not used for controlling the actual motor (you'd probably break the motor if you tried). The actual inside of the speed controller consists of an H-Bridge which allows for variable voltage control. So, by limiting the speed, you're also limiting the torque output from the motor. However, you may want to do this as it can allow finer grained control over the robot.

Matt

Last edited by Matt Leese : 11-11-2005 at 11:47.