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Unread 12-01-2017, 14:05
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Re: Realistic high goal scoring rate

Quote:
Originally Posted by Kevin Sevcik View Post
I need to revisit my flywheel spinup spreadsheet and add a few new features to it. Think I'll do that tonight.

At any rate, if you're using an encoder to do closed loop control of your shooter speed, you want a specific gear ratio to maximize your rate of fire. You want a gear ratio that has the motor spinning at 1/2 its free speed when your wheel is at target speed, or something very close to this (err on the side of a bit more reduction). This puts the motor at its peak power point when its at firing speed, which will minimize the recovery time to target speed, or atleast minimize the speed drop when dumping an entire load of balls.

Interestingly, this is not the gear ratio that spins the motor up from zero to target speed the fastest. That depends on the system dynamics, but the example I'm working with has that ratio at 40% more reduction, and increases recovery time by 16%. Which would give you a rate of fire of 86% the theoretical max.
I don't think that's how it works. The motor is only at max power spinning half its free speed at full voltage, IE if the load the motor is under is slowing it down that much. If you're just spinning the motor at half its free speed with speed control, you're just applying a bit more than 6 volts to the motor (a bit more to account for friction losses etc). You definitely do want to be spinning a flywheel at less than 100% speed so it has some headroom to recover with, but I don't think it's exactly half voltage or half free speed either.
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