paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

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[Ri3D] The GreenHorns 2016 Present: Rivvet by Ginger Power

Post any questions about The GreenHorns' 2016 Ri3D Robot here. Our reveal video will be posted here tomorrow before 3PM. The perfectionists on our team were so broken by Ri3D that they needed to make up for it by taking the time to make a perfect reveal video.

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

Sorry we're a little late, but here is our 2016

Reveal Video

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

How difficult was turning for you guys with a 4WD? Did you notice that the batteries were draining quickly?

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

I wouldn't want a 4 wheel drive robot. Turning on that concrete wasn't terrible, but carpet would've been a challenge. I've said before, if we had access to 6 pneumatic wheels that's what we would've done.

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

Ginger,

Did you find with longer shots that the ball would sometimes travel left or right, and not always straight? We've looked at a shooter design like yours and one of the considerations is spinning both sides at the same speed.

Nice job on the robot. In 3 days you made something that will do well at many districts!

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

The ball flew very straight in our testing. The real problem with shooting from far away will be the size of the goal. As others have noted it's the smallest goal relative to game object in FRC history. Given how safe shooting from up against the tower seems to be, I think that's the way to go. I think it would be capable of scoring from the outer works, but I haven't tested it enough to give you a guarantee.

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

Would a pair of mini-CIM's be likely to be sufficient to get similar results for the shooter?

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

Reveal Video

**Fixed the link**

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

Does the shooter use two Mini - CIM's ?

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

Have you read their whitepaper linked to in the initial post?

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

As Hallry said, I've written a white paper about our design that details Rivvet. We did use mini CIMs at 1:1, but if I had any motors/gearboxes available to me I'd use a 775pro at a 2:1 ratio driving 4" wheels. This will give you more torque as well as more speed. Then you would have the ability to limit the speed via code and make it more robust to changes in the battery voltage.

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

I apologize if this is a silly question, as I am not a gearbox expert. You say that you would use the 775pro at a 2:1 ratio, but the versa planetaries that VEX sells start at 3:1. How would you get 2:1?

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

Not with a versa planetary :p I haven't done a 2:1 ratio before, so I'm not sure about the optimal way to do it. One way I can think of would be to drive a 16 tooth sprocket/belt off the motor and run a chain/belt to a 32 tooth sprocket/pulley on the intake wheels.

You could also just run the 775pro at 3:1 in a versa, which would still be faster and more powerful than mini CIMs at 1:1

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

That makes sense. Thanks for the quick and insightful help!

Re: paper: [Ri3D] The GreenHorns 2016 Present: Rivvet
 

No problem! If you have any questions just pm me here. I check Chief Delphi more often than I check Facebook and Twitter combined. It's probably unhealthy actually...