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Eric Scheuing 12-01-2017 12:31

Realistic high goal scoring rate
 
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 :)

StAxis 12-01-2017 12:33

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by Eric Scheuing (Post 1629981)
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.

notmattlythgoe 12-01-2017 12:33

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by Eric Scheuing (Post 1629981)
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 :)

Well, that depends on how many balls you can shoot at the same time...

A-A-Ron (Sum) 12-01-2017 12:35

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by StAxis (Post 1629982)
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 12-01-2017 12:40

Re: Realistic high goal scoring rate
 
how about 12 fuel per second?

gorrilla 12-01-2017 12:48

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by MaGiC_PiKaChU (Post 1629990)

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 12-01-2017 12:49

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by gorrilla (Post 1629997)
Are you guys French?

yes, sorry about that :rolleyes:

gorrilla 12-01-2017 12:51

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by MaGiC_PiKaChU (Post 1629998)
yes, sorry about that :rolleyes:

No problem I was just surprised lol

Kevin Sevcik 12-01-2017 12:54

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by MaGiC_PiKaChU (Post 1629990)

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 12-01-2017 12:56

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by Kevin Sevcik (Post 1630002)
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

Eric Scheuing 12-01-2017 13:14

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by notmattlythgoe (Post 1629983)
Well, that depends on how many balls you can shoot at the same time...

Part of why I'm asking. You tell me ;)

EDIT:
Quote:

Originally Posted by MaGiC_PiKaChU (Post 1629990)

Very cool! How to you plan on implementing that hopper in a 36" (or 24") tall robot :p

Chris is me 12-01-2017 13:22

Re: Realistic high goal scoring rate
 
I think top teams will get to a dozen per second, absolutely. Multiple ways to accomplish this shooting task this year - if the way you have in mind can't do it, think outside the box a little.

Quote:

Originally Posted by Kevin Sevcik (Post 1630002)
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.

This isn't 2016 - volume and accuracy are tradeoffs where the right answer very well may be on the side of volume. Turreted shooter in 2009 could be more accurate than dumpers, but dumpers certainly were the more dominant design in general that year. This year's game has five times as many game pieces as 2009!

MaGiC_PiKaChU 12-01-2017 13:31

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by Eric Scheuing (Post 1630020)
Very cool! How to you plan on implementing that hopper in a 36" (or 24") tall robot :p

it seems possible for now to stay under 24", that would allow for a larger drive base, and a larger intake

Kevin Sevcik 12-01-2017 14:01

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by MaGiC_PiKaChU (Post 1630006)
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 12-01-2017 14:05

Re: Realistic high goal scoring rate
 
Quote:

Originally Posted by Kevin Sevcik (Post 1630066)
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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