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  #16   Spotlight this post!  
Unread 05-02-2012, 16:11
Andrew Lawrence
 
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Re: Team 2363 turret actution

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Originally Posted by Tom Line View Post
O Rly? Get back to me in after a couple of regionals. I think you'll be very surprised by what the top teams do in autonomous mode.
Is 1718 able to accurately shoot into a hoop while driving away from it? I'd love to see the video, if you're willing to show it.

I never said it wasn't possible, however it's unlikely, and easy to mess up.
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Unread 05-02-2012, 16:23
Andrew Lawrence
 
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Re: Team 2363 turret actution

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Originally Posted by LinuxArchitect View Post
No offense, but I always laugh when people use the terms forward/front and backward/rear. When you do, you are limiting your actions. Except for the act of driving itself, who cares? It's not like you are actually sitting on the robot facing the forward direction of the drivetrain and you have to look over your shoulder to shoot "backwards". Your robot can move and face in any direction. Therefore, you might want it to shoot in any direction.

In this case, perhaps you are in the process of collecting a ball. Murphy says the ball will be in the most awkward location possible. Your design decision is, can I shoot immediately, or do I need to rotate the chassis. As mentioned, a small deadzone might be acceptable. But full 180 turns to shoot might not be.
Understood, however I don't understand your logic behind the no front/back thing. You can't just drive your car backwards on a freeway and say it's forwards. For the most part, robots are going to have a designated "front" and a designated "back". That means when you go forward on your controller, your robot will go forwards.

I agree. Your robot itself is capable in moving every which direction it wants. So why have a totally separate part of the robot that turns independently of your robot when you can turn your robot just as easily in any way it wants? Unless your robot can hardly turn, or you haven't considered the robot's orientation a factor during the match, turning a robot 180 degrees is the same as turning a turret 180 degrees, if not faster since most drives are powered by 4 CIMs, whereas most turrets are going to be powered by one of the weaker motors. I've seen robots turn 180 degrees pretty fast.

As for limiting actions, isn't that what engineering is all about? Tradeoffs. Torque vs speed is my favorite one. And sometimes you end up limiting things you don't really need anyways.

As for your Murphy's law example (My favorite law ), there are so many ways to engineer your robot so that doesn't happen, and good driver training will easily be able to fix a ball in an awkward position.

I'm not at all saying turrets are bad, and love all of the videos that are being posted. Just that there are ways to make an effective robot without turrets.
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Unread 05-02-2012, 18:47
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Re: Team 2363 turret actution

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Originally Posted by wireties View Post
we turned the entire rotating plate into a giant gear - so no chain
How did you cut your teeth?
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  #19   Spotlight this post!  
Unread 05-02-2012, 19:06
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Re: Team 2363 turret actution

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Originally Posted by SuperNerd256 View Post
So why have a totally separate part of the robot that turns independently of your robot when you can turn your robot just as easily in any way it wants?
Precision. To make an accurate long distance shot, the yaw angle must be controlled very precisely. During concepting, we knew we could design and fabricate a turret which could mechanically aim very precisely. We suspected that control of the shooter yaw angle via the drivetrain might not be very precise. The software can be written so the vision system can set shooter yaw angle by controlling either the drive train or the turret. We decided to go ahead and built a turret as a reasonable response to reducing technical risk. If it turns out that yaw control of the robot gives us everything we need, we'll keep the turret locked and only use the drive train. On the other hand, if the drive train is unable to position the shooter precisely enough, we have the turret actuator to fall back on, even if it doesn't rotate a full 360 degrees.

If, by some miracle, the computer runs fast enough, and the software is good enough, it is conceivable that we could keep the shooter locked on the target with an accurate "firing solution" such that we just drive around picking up balls and firing them continuously through the hoop, on the move. Can't do that without a turret.

As a mechanical guy, I always want to say, "The robot would be so much cooler if only the software could do ..." I never want to hear, "The robot would be so much cooler of only it was mechanically able to do ..." Of course, both software and mechanical people will always say, "If only the drivers were better, the robot could do ..." and the drivers will say, "If only we had the robot sooner to practice with, we could have done ..." Such is life when asked to do the impossible with too little time and not enough money.
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Last edited by ToddF : 05-02-2012 at 19:14.
  #20   Spotlight this post!  
Unread 05-02-2012, 19:09
Andrew Lawrence
 
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Re: Team 2363 turret actution

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Originally Posted by ToddF View Post
Precision. To make an accurate long distance shot, the yaw angle must be controlled very precisely. During concepting, we knew we could design and fabricate a turret which could mechanically aim very precisely. We suspected that control of the shooter yaw angle via the drivetrain might not be very precise. The software can be written so the vision system can set shooter yaw angle by controlling either the drive train or the turret. We decided to go ahead and built a turret as a reasonable response to reducing technical risk. If it turns out that yaw control of the robot gives us everything we need, we'll keep the turret locked and only use the drive train. On the other hand, if the drive train is unable to position the shooter precisely enough, we have the turret actuator to fall back on, even if it doesn't rotate a full 360 degrees.

If, by some miracle, the computer runs fast enough, and the software is good enough, it is conceivable that we could keep the shooter locked on the target with an accurate "firing solution" such that we just drive around picking up balls and firing them continuously through the hoop, on the move. Can't do that without a turret.
Please do that! I wanna see that so badly!
  #21   Spotlight this post!  
Unread 05-02-2012, 19:20
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Re: Team 2363 turret actution

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Originally Posted by SuperNerd256 View Post
Please do that! I wanna see that so badly!
You and me both. I've been harping on the software folks to stick a laser pointer on a pan/tilt, mount it on last year's robot, and show they can hold the red dot in the center of the vision square while the robot drives around. If they can do that, we can make baskets on the fly. That's the video I want to see posted on youtube.
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  #22   Spotlight this post!  
Unread 05-02-2012, 22:43
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Re: Team 2363 turret actution

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Originally Posted by ToddF View Post
How did you cut your teeth?

One of our sponsors is a sheet metal fabrication shop. So we drew it in SolidWorks and they made it for us. They make several and we sandwich them together with rivets to yield cheap aluminum gears of any size or shape. We "borrowed" this technique from the RoboWranglers.

HTH
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