Realistic high goal scoring rate

[StAxis]

Originally Posted by Eric Scheuing

I keep seeing discussion about the high goal scoring rate required to maximize score. This is all well and good, but it's all theoretical. What do you think is a realistic rate of fire for a high goal shooter for an individual robot. An explanation of how you reach that number would be appreciated

I think realistically a well refined Ri3D 1.0 shooter could reach 3 balls/sec. And I believe there will be at least one powerhouse team with more than one shooter on their robot.

[A-A-Ron (Sum)]

Originally Posted by StAxis

I think realistically a well refined Ri3D 1.0 shooter could reach 3 balls/sec. And I believe there will be at least one powerhouse team with more than one shooter on their robot.

This is also the sentiment from my team. We are going into this season under the idea that great teams will have 2 or 3 shooters at around 3 fuel/second.

[MaGiC_PiKaChU]

how about 12 fuel per second?

[gorrilla]

Originally Posted by MaGiC_PiKaChU

how about 12 fuel per second?

Are you guys French?

My team was testing out our shooter yesterday and we were able to do at least 3 per second pretty accurately

[MaGiC_PiKaChU]

Originally Posted by gorrilla

Are you guys French?

yes, sorry about that

[gorrilla]

Originally Posted by MaGiC_PiKaChU

yes, sorry about that

No problem I was just surprised lol

[Kevin Sevcik]

Originally Posted by MaGiC_PiKaChU

how about 12 fuel per second?

Yes, but accuracy. At that distance you're going to need much tighter control of the ball velocity. And the closer you get, the lower your rate of fire has to be.

[MaGiC_PiKaChU]

Originally Posted by Kevin Sevcik

Yes, but accuracy. At that distance you're going to need much tighter control of the ball velocity. And the closer you get, the lower your rate of fire has to be.

we were shooting from that distance to see how the wheel slowed down. By adding mass to the flywheel and shooting from closer, accuracy will go up a lot

[Kevin Sevcik]

Originally Posted by MaGiC_PiKaChU

we were shooting from that distance to see how the wheel slowed down. By adding mass to the flywheel and shooting from closer, accuracy will go up a lot

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.

[Chris is me]

Originally Posted by Kevin Sevcik

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.